Cooperativismo y Desarrollo, May-August 2026; 14(2), e1015
Translated from the original in Spanish

Original article

Procedure for improving the production process with a circular economy approach in vegetable canning companies

Procedimiento para el perfeccionamiento del proceso de producción con enfoque de economía circular en empresas de conservas de vegetales

Procedimento para a melhoria do processo produtivo com uma abordagem de economia circular em empresas de conservas de vegetais

Luis Tomás Bravo Rodríguez¹ 0009-0009-5368-2088 luistomas@upr.edu.cu
Jineht Pérez Martínez² 0000-0002-8160-0475 jperezm@upr.edu.cu
Carlos Cesar Torres Paez² 0000-0001-7956-5079 carlosc@upr.edu.cu

¹ Vegetable Canning Company "La Conchita". Cuba.
² University of Pinar del Río "Hermanos Saíz Montes de Oca". Cuba.

Received: 26/06/2026
Accepted: 4/09/2026

ABSTRACT

This research proposes a procedure for improving the production process using a circular economy approach at the "La Conchita" Vegetable Canning Company, located in Pinar del Río, Cuba. The study begins with the contradiction between the company's current linear production model and the principles of the circular economy, as evidenced by the absence of waste management metrics, a lack of infrastructure for waste sorting and processing, technological limitations, and the systematic waste of raw materials. Through a comprehensive assessment that combined direct observation, surveys of workers and managers, the Delphi method with experts, and the Load Capacity Management System, six root causes of the inefficient tomato puree production process were identified: poor working conditions, difficulties in solid waste management, undertrained staff, machinery in poor condition, demotivation and labor inefficiency, and low job content. The designed procedure is structured in four stages following the PDCA cycle (Plan, Do, Check, Act), integrating twelve operational steps ranging from the analysis of material flow to the standardization of documentation and the planning of new improvement cycles. Validation using the user validation technique yielded a Group Satisfaction Index of 0.942, confirming the relevance, practical feasibility, and perceived effectiveness of the proposed procedure.

Keywords: circular economy; production management; canned vegetables; procedure; agro-industrial waste.

RESUMEN

La presente investigación propone un procedimiento para el perfeccionamiento del proceso de producción con enfoque de economía circular en la Empresa de Conservas de Vegetales "La Conchita", ubicada en Pinar del Río, Cuba. Se parte de la contradicción existente entre el modelo de producción lineal vigente en la empresa y los principios de la economía circular, evidenciada en la ausencia de métricas de gestión de residuos, carencia de infraestructura para su clasificación y procesamiento, limitaciones tecnológicas y desaprovechamiento sistemático de la materia prima. Mediante un diagnóstico integral que integró observación directa, encuestas a trabajadores y directivos, método Delphi con expertos y el Sistema de Gestión de la Capacidad de la Carga, se identificaron seis causas fundamentales del ineficiente proceso productivo del puré de tomate: malas condiciones de trabajo, dificultades en la gestión de residuos sólidos, personal poco capacitado, maquinarias en mal estado, desmotivación e ineficiencia laboral y escaso contenido de trabajo. El procedimiento diseñado se estructura en cuatro etapas bajo la lógica del ciclo (Planificar, Hacer, Verificar, Actuar), integrando doce pasos operativos que abarcan desde el diagnóstico del flujo de materiales hasta la estandarización documental y la proyección de nuevos ciclos de mejora. La validación mediante la técnica de validación por usuarios arrojó un Índice de Satisfacción Grupal de 0,942, lo que confirma la pertinencia, viabilidad práctica y efectividad percibida del procedimiento propuesto.

Palabras clave: economía circular; gestión de la producción; conservas vegetales; procedimiento; residuos agroindustriales.

RESUMO

Esta pesquisa propõe um procedimento para melhorar o processo produtivo na Empresa de Conservas de Vegetais "La Conchita", em Pinar del Río, Cuba, adotando uma abordagem de economia circular. O estudo aborda o conflito entre o atual modelo de produção linear da empresa e os princípios da economia circular, um conflito evidenciado pela ausência de métricas de gestão de resíduos, infraestrutura insuficiente para triagem e processamento de resíduos, limitações tecnológicas e subutilização sistemática de matérias-primas. Por meio de um diagnóstico abrangente, incorporando observação direta, pesquisas com trabalhadores e gestores, o método Delphi com especialistas e um Sistema de Gestão da Capacidade de Carga, foram identificadas seis causas raiz para a ineficiência do processo de produção de purê de tomate: condições de trabalho precárias, dificuldades na gestão de resíduos sólidos, pessoal inadequadamente treinado, maquinário em más condições, baixa motivação e ineficiência da mão de obra, e conteúdo de trabalho insuficiente. O procedimento elaborado estrutura-se em quatro etapas, seguindo a lógica do ciclo PDCA (Planejar-Executar-Verificar-Agir), integrando doze passos operacionais que vão desde o diagnóstico dos fluxos de materiais até a padronização de documentos e o planejamento de futuros ciclos de melhoria. A validação, realizada por meio da técnica de validação pelo usuário, resultou em um Índice de Satisfação do Grupo de 0,942, confirmando a relevância, a viabilidade prática e a eficácia percebida do procedimento proposto.

Palavras-chave: economia circular; gestão da produção; conservas vegetais; procedimento; resíduos agroindustriais.

INTRODUCTION

Twenty-first-century companies operate in an environment that demands ever-increasing results in terms of volume, variety, quality, lead time, and price, while facing multiple constraints on their structure and resources. This fundamental contradiction must be resolved by applying the philosophy of systematically raising the level of satisfaction of social demands, which requires more optimal, efficient, and effective process management, even in scenarios of dwindling resources. Internationally, vegetable canning companies are characterized by operating within a mature and highly competitive industry, whose activity is intrinsically linked to the seasonality of harvests and the urgent need to quickly process perish e raw materials. This industry is a crucial sector for the growth of countries' gross domestic product (Chavesta et al., 2025), and its dynamics place these companies at a constant crossroads between production efficiency and the management of the significant volumes of organic byproducts generated by their processes -a challenge that is driving them toward the adoption of circular economy models (Massaro et al., 2021; SYSTEMIQ & Ellen MacArthur Foundation, 2017).

Global environmental problems have escalated at an alarming rate. According to the World Health Organization, nearly two million people die each year from pollution-related diseases; more than 17 million hectares of forest are destroyed annually; and four million metric tons of household and industrial waste are generated daily. The linear production model, centered on the "take, make, dispose" logic, is unsustainable, as both natural resources and energy sources are not unlimited. It has been shown that, if we continue with this linear economic model, by the year 2050 we will need three times as many materials, 70% more food, and our demand for water and energy will increase by 40% (Barret et al., 2018, cited by Da Costa Pimienta, 2022). In this scenario, the circular economy emerges as a sustainable and relevant alternative in the current context, where the terms "circular economy" and "sustainability" are gaining ground in academia, industry, and among policymakers (Geissdoerfer et al., 2017; González & Pomar Fernández, 2021).

For Cuba, issues related to waste management are part of the country's strategy for socioeconomic development. The Guidelines for the Economic and Social Policy of the Party and the Revolution, updated at the 7th Congress of the Communist Party of Cuba (PCC), state that "it must be promoted the intensification of recycling and the increase in the added value of recovered products, prioritizing activities with greater economic impact using fewer resources" (PCC, 2021, p. 15). In this context, "La Conchita" Vegetable Canning Company, founded in 1937 and located in Pinar del Río, faces the challenge of maintaining its competitiveness in a globalized market where operational efficiency, environmental sustainability, and social responsibility have become critical success factors. Its traditional production model, based on a linear economic system, generates inherent inefficiencies and a significant environmental impact, which motivated this research.

The preliminary assessment revealed that waste from the production lines is collected for potential reuse, but the strategic management of this activity is inefficient: there are no historical metrics, monitoring indicators, or reports. There are gaps in the infrastructure needed to collect, sort, and process waste, as well as limitations in technological innovation and a lack of tools to identify waste levels for subsequent reuse, leading to a waste of raw materials. These elements constitute the scientific problem: the contradiction between the implemented linear production model and the principles of the circular economy, which seek to maximize the utility of resources, minimize waste, and create closed-loop value cycles. The objective of this research is to design a procedure to optimize the production process at "La Conchita" Vegetable Canning Company, which, by adopting a circular economy approach, will contribute to increasing resource utility, efficiency, and effectiveness, as well as the utilization of production waste.

MATERIALS AND METHODS

The research is grounded in the dialectical materialist method and employs a mixed-methods approach that integrates qualitative and quantitative data analysis to obtain a holistic understanding of the current state of the tomato puree production process at the company under study. A descriptive-diagnostic study design is adopted, based on the principle of methodological triangulation, using various data sources and collection techniques to validate the findings and minimize the biases inherent in each individual method.

The logical-historical method was used to determine the theoretical and methodological background of production management with an emphasis on the circular economy; the hypothetical-deductive method to formulate the research hypothesis and explain the results obtained; analysis and synthesis to study the various aspects related to the integration of the circular economy model; and the systemic method to characterize the object and scope of the study, specifying the constituent elements and the relationships established among them.

A set of techniques and instruments specifically designed for the diagnosis was applied. Direct observation sessions were conducted in the pulping area, using a structured observation guide to record technical and organizational deficiencies. A survey was designed for 35 direct employees in the pulping area, consisting of 10 items that combined dichotomous closed-ended questions to assess compliance with production volumes, availability of protective equipment, waste utilization, equipment condition, training received, and operational efficiency. Concurrently, a survey was administered to six management executives, consisting of 7 items aimed at evaluating waste management, equipment condition, and training received. The instrument was validated through expert judgment.

The Delphi method was applied with a group of five experts and a facilitating group of four specialists, through three iterative rounds to identify, confirm, and weight the deficiencies affecting the production process, using the concordance coefficient and Kendall's nonparametric docima (W). Additionally, a documentary and technical analysis of the process was conducted using the Load Capacity Management System (SGCC in Spanish) to calculate the time buffer, the operational load, the correspondence coefficient, process capacity, and the loss coefficient. To validate the procedure, the Iadov technique was used with 19 managers and specialists involved in the production process.

RESULTS AND DISCUSSION

The theoretical analysis of the circular economy in the canning industry is based on its conception as a restorative and regenerative production model by design, which replaces the linear "extract-produce-consume-dispose" model with closed-loop systems where waste from some processes becomes input for others. In the canning industry, particularly in the production of tomato puree, this approach takes on strategic importance due to the high volume of byproducts generated, such as skins, seeds, and pomace; which, from a circular perspective, are no longer viewed as losses but rather as exploitable value streams through hierarchical valorization strategies, such as the extraction of bioactive compounds (lycopene, pectin), the production of animal feed, or the creation of organic soil amendments. The circular economy not only reduces environmental pressure but also serves as a direct driver of productive growth: by minimizing raw material losses, optimizing technological yields, and reducing costs associated with waste disposal, the company increases its efficiency and expands its effective production capacity, while also generating economies of scope through new business lines derived from byproducts. Thus, the relationship between circularity and increased productivity is not antagonistic but synergistic, since each metric ton of recovered waste represents a net increase in the utilization of processed material, raising the circularity index and, simultaneously, the overall productivity of the system (Geissdoerfer et al., 2017).

Comprehensive diagnosis of the production process

The vegetable canning company "La Conchita" has an approved workforce of 411 employees and four production plants: Sweets and Syrup, Pulping, Fruit Pastes, and Mayonnaise and Juices. The diagnosis focused on the Pulping Plant (, specifically on the tomato puree line, whose production process comprises nine main technological operations: raw material reception, washing and sorting, crushing, preheating, re-crushing, pulp concentration, sterilization, filling and capping, and labeling. The crushing and screening operations account for the greatest losses of raw materials, with 10% in seeds and skins and 4% in waste, respectively.

The results of the worker survey revealed that 68% believe that planned production volumes are not being met, 83% agree on the need to implement more efficient operations, and 89% have not received training in Process Management. Regarding waste management, although 66% perceive that waste is being maximized, this contradicts the 86% who believe that solid waste is not given the necessary attention. Fifty-five percent of respondents believe that the machinery is obsolete and does not operate at its maximum capacity. For their part, managers possess a solid conceptual foundation in environmental management, but half rate waste management in the pulping area as fair, and one-third consider it insufficient -a finding specifically attributed to a lack of oversight by plant managers.

The application of the Delphi method made it possible to identify and weigh six main deficiencies: poor working conditions (deteriorated floors, lack of climate control and lighting), difficulties in solid waste management, poorly trained staff, machinery in poor condition, demotivation and inefficiency at work, and a lack of meaningful work. The concordance coefficient exceeded 70% for six of the eight deficiencies initially identified. Kendall's coefficient yielded W = 0.32, which, while suggesting dispersion in the relative weightings, does not invalidate the qualitative consensus reached in the second round.

The SGCC analysis quantified the production disarticulation as a loss coefficient of 80%, stemming from the divergence between the capacity of the limiting point (concentration: 321.56 t/month) and that of the fundamental point (filling: 1,669.52 t/month). This result highlights a serious underutilization of the process, which increases production costs and limits the ability to meet demand. The triangulation of sources allowed for the consolidation of the comprehensive diagnosis, represented by an Ishikawa diagram that interrelates the six causes validated as causal factors of the inefficient production process.

Procedure for improving the production process using a circular economy approach

The designed procedure constitutes an original methodological contribution that integrates, in a twelve-step operational sequence, the diagnosis of material flow, the identification of root causes of waste generation, the assessment of circularity potential, technological optimization, differentiated waste management, human capital training, the measurement of circular performance indicators, internal auditing, satisfaction assessment, analysis of lessons learned, documentation standardization, and the planning of new improvement cycles. All of this is structured according to the dynamic logic of the PDCA cycle (Plan-Do-Check-Act).

The methodological foundation of the procedure is based on the integration of three complementary approaches: business process management (Dumas et al., 2018), the circular economy as a regenerative paradigm (SYSTEMIQ & Ellen MacArthur Foundation, 2017), and continuous improvement methodologies applied to contexts of budgetary constraints. The procedure is guided by five principles derived from the assessment: circular traceability, waste hierarchy, technological feasibility under resource-constrained conditions, comprehensive participation, and measurement and continuous improvement.

The objective of the procedure is to optimize the tomato puree production process at "La Conchita" Vegetable Canning Company by adopting a circular economy approach, in order to increase resource utility, efficiency, and effectiveness, as well as the utilization of production waste.

The procedure covers the tomato puree production process from the receipt of raw materials to the storage of the finished product, explicitly including the management of byproducts and waste generated in each technological operation.

The limits of the procedure is as follows:

• It does not include the management of industrial liquid waste (wastewater), although it does address its minimization at the source.
• It does not include investments in new high-tech machinery, focusing instead on optimizing existing equipment.
• It is initially applied to the tomato puree line, with the potential for replication to other lines in the Pulping Plant.

The procedure is structured into four stages that follow the logic of the PDCA cycle. Each phase has a specific objective and is broken down into concrete operational steps described in Tables 1, 2, 3, and 4.

Stage I: Planning for circular improvement

Stage Objective: To assess the current state of the tomato puree production process, identify opportunities for circularity in each technological operation, and design a comprehensive improvement plan that integrates waste reduction at the source, internal reuse of byproducts, and external recovery of unavoidable waste.

Table 1. Steps in stage 1

Step 1. Analysis of the current material flow
Element	Content
Description	Develop a detailed map of the material flow in the tomato puree production process and evaluate the technical and economic potential of applying the three principles of the circular economy (reduce, reuse, recover) to each type of waste identified.
Actions to be taken	Identify and quantify inputs (raw materials, water, energy) and outputs (finished product, solid and liquid waste) in each technological operation. Calculate the Material Efficiency Index (MEI) per operation: MEI = (Mass of useful product / Total mass of inputs) × 100. Create a Sankey diagram of the material flow. For each type of waste (seeds and skins, spoiled tomatoes, cooking water, packaging materials), evaluate: Path 1 (Reduction at the source), Path 2 (Internal reuse), Path 3 (External recovery). Calculate the Circular Potential Index (CPI): CPI = (Potentially circularizable mass / Total mass of waste generated) × 100. Estimate the preliminary economic impact of each pathway (savings on raw materials, revenue from byproducts).
Inputs	Production records for the last 12 months; equipment technical data sheets; quality specifications (NC 108:2012); SGCC results; data on raw material costs and prices of potential byproducts.
Techniques to be used	Document analysis; structured direct observation; direct measurement of masses and volumes; Sankey diagram; preliminary cost-benefit analysis; multi-criteria decision matrix (IPC, economic impact, technical feasibility).
Time	4 weeks
Person in charge	Head of the Pulping Department, with support from the quality specialist, the cost accountant, and guidance from the Pinar del Río Center for Information and Technology Management (CIGET).
Outputs	Quantified material flow map; circularity potential matrix by waste type with calculated IPC; technical-economic report on circularity potential.
Step 2. Identification of root causes of waste generation
Element	Content
Description	Analyze the technical, organizational, and human causes that lead to waste generation in operations with the highest losses, prioritizing those amenable to intervention.
Actions to be taken	Apply the Ishikawa (fishbone) diagram to each prioritized operation, identifying causes in the following categories: labor, machinery, materials, methods, environment, and measurement. Classify the causes into: technological, procedural, human, and design-related. Create a cause prioritization matrix based on impact on waste generation (scale 1-5) and feasibility of intervention (scale 1-5). Select causes with a combined score of ≥ 6 for priority intervention. Formulate solution hypotheses for each prioritized cause.
Inputs	Material flow map from Step 1; results of surveys of workers and managers; equipment maintenance records (last 24 months); technical operating specifications.
Techniques to be used	Ishikawa diagram; prioritization matrix (impact vs. effort); semi-structured interviews with operators and maintenance technicians; technical review of failure records; correlation analysis between variables.
Time	2 weeks
Person in charge	Quality specialist, with participation from the plant manager, maintenance specialist, and a representative of the operational workers.
Outputs	Ishikawa diagrams by prioritized operation; matrix of prioritized causes with classification and scoring; solution hypotheses by prioritized cause.
Step 3. Design of the Circular Improvement Plan (CIP)
Element	Content
Description	Formulate a comprehensive intervention plan that integrates the prioritized reduction, reuse, and recovery actions, with specific objectives, a timeline, allocated resources, and monitoring indicators.
Actions to be taken	Define specific improvement objectives for each operation with quantifiable targets. Design corrective and preventive actions for each prioritized cause. Allocate human, material, and time resources, with clearly defined responsible parties. Establish an implementation timeline: short term (1-3 months), medium term (4-6 months), long term (7-12 months) Define monitoring indicators, measurement frequencies, and targets. Prepare a preliminary budget, distinguishing between low-cost and medium-cost investments. Validate the plan internally with the Board of Directors.
Inputs	Step 1 circularity potential matrix; Step 2 prioritized causes matrix; available resources; Company Development Strategy; annual production plan; current regulations (NC 108:2012).
Techniques to be used	Gantt chart; urgency-importance matrix; brainstorming; line-item budgeting.
Time	2 weeks
Person in charge	Board of Directors, with technical implementation by the Technical and Development Department.
Outputs	Documented and approved Circular Improvement Plan; implementation schedule (Gantt chart); preliminary budget; monitoring indicators matrix with targets and frequencies.

Source: Own elaboration

Phase II: Implementation of improvements

Objective of this stage: To execute the planned actions in the actual production process, modifying technological operations, establishing differentiated waste management, and training staff.

Table 2. Steps in stage 2

Step 4. Technological optimization of critical operations
Element	Content
Description	Implement technical adjustments to critical operations to reduce waste generation and improve process efficiency, using existing equipment.
Actions to be taken	Adjust technical processes in operations. Establish visual quality control of waste. Adjust operational capacity to align with the SGCC’s limiting point. Train operators on how to use the system and respond to deviations.
Inputs	Approved PPC; equipment data sheets; spare parts and materials; product quality specifications.
Techniques to be used	Mechanical adjustment of equipment; instrument calibration; in-line quality control; systematic recording of parameters; pilot tests of adjustments.
Time	4 weeks
Person in charge	Pulp Mill Manager, with implementation by the maintenance specialist and supervision by the quality specialist.
Outputs	Equipment adjusted and calibrated with records; 0.6 mm screen installed and operational; temperature recording system operational; parameter control sheets for each operation.
Step 5. Implementation of differentiated waste management and reorganization of the area
Element	Content
Description	Establish the system for the sorting, collection, recording, and separate disposal of waste, and carry out repairs and reorganization of the work area to eliminate environmental and organizational deficiencies.
Actions to Be Taken	Waste management: design and install color-coded waste bins; mark areas with pictograms; design and implement a Daily Waste Control Form; designate a person responsible for recording data per shift; establish separate disposal routes. Work Area Reorganization: Analyze the current flow of materials; redesign the layout to minimize transport distances; define separate zones; mark the floor with traffic lines. Repairs: Repair damaged floors; repair or replace lighting; improve ventilation. Preventive maintenance: develop a schedule for critical equipment; assign personnel responsible; record actions in technical logs.
Inputs	Approved PPC; circularity potential matrix (Step 1); containers, signage, and office supplies; preliminary agreements with waste recipients; budget for repairs; floor plans of the area.
Techniques to be used	Design of a color-coded sorting system; design of record forms; 5S technique; process flow analysis; floor plan (layout); repair project management.
Time	5 weeks
Person in charge	Pulp Mill Manager, with implementation by the maintenance specialist and supervision by the quality specialist.
Outputs	Separate waste container system installed and operational; Daily Waste Control forms in use; agreements in place with waste recipients; area reorganized with a new layout; floors, lighting, and ventilation repaired; preventive maintenance schedule underway.
Step 6. Training and human capital development
Element	Content
Description	Address the identified training gap through a comprehensive training program that prepares staff to operate within a circular economy framework and manage the new procedures.
Actions to be taken	Design a program with distinct modules. Conduct theoretical and practical sessions at times that do not interfere with production; use tailored instructional materials with examples from the company; conduct practical demonstrations in the production area; administer knowledge assessments. Establish a recognition system: monthly recognition for the shift with the best IEM, a “Circular Operator” badge, and links to salary incentives. Record attendance and evaluations; conduct quarterly refresher sessions; assess effectiveness through satisfaction surveys and indicator measurements.
Inputs	Approved PPC; training needs assessment results; competency profiles; reference materials and regulations; training budget; facilities for theoretical sessions.
Techniques to be used	Theoretical and practical training; case studies; simulation of operational situations; knowledge assessment; change management (communication, participation, recognition).
Time	5 weeks
Person in charge	Human Capital Directorate, with content development handled by the Technical and Development Directorate and advisory support from CIGET Pinar del Río.
Outputs	Training program implemented and documented; attendance records and evaluations; instructional materials available; recognition system implemented; implementation and evaluation report.

Source: Own elaboration

Phase III: Monitoring and follow-up

Objective of this stage: Verify compliance with the PPC, measure results using circular performance indicators, audit the system, and evaluate customer satisfaction.

Table 3. Steps in stage 3

Step 7. Measurement of circular performance indicators
Element	Content
Description	Apply the indicator system designed to quantitatively assess the procedure’s impact on material efficiency, waste reduction, byproduct recovery, and production capacity.
Actions to be taken	Calculate the indicator system monthly and prepare a consolidated monthly report in graphical and tabular formats, including an analysis of variations and alerts for deviations.
Inputs	Daily Waste Control Forms (Step 5); monthly production records; updated SGCC data; targets established in the PPC; calculation tools (spreadsheets).
Techniques to be used	Descriptive statistics; trend analysis; comparison with baseline; dashboards; deviation analysis.
Frequency	Monthly
Person in charge	Quality specialist, with support from the plant manager and the cost accountant.
Outputs	Monthly report on circular performance indicators; trend charts; deviation alerts; consolidated quarterly report.
Step 8. Internal audit of the circular management system
Element	Content
Description	Conduct periodic audits to verify compliance with procedures, the correct implementation of new practices, and the effectiveness of the implemented waste management system.
Actions to be taken	Audit records and documentation: verify the existence, up-to-date status, and correct completion of Daily Waste Control Forms; review consistency between production and waste records; verify preventive maintenance records. Physically audit the area: inspect the condition of recycling bins; verify correct use by operators; assess the condition of signage and markings; verify the implementation of new operating procedures. Audit training: verify attendance records and evaluations; interview workers to assess knowledge retention; verify practical application. Identify nonconformities: record deviations; classify them as minor, major, or critical; formulate corrective actions with responsible parties and deadlines. Prepare an audit report detailing findings, nonconformities, and opportunities for improvement.
Inputs	Documented and approved procedure; Daily Waste Control forms; maintenance records; training files; audit checklist; QMS regulations (adapted ISO 9001).
Techniques to be used	Internal audit by sampling; structured direct observation; interviews with employees and managers; systematic document review; analysis of nonconformities.
Frequency	Quarterly
Person in charge	Internal QMS auditor, with participation from the Quality Committee.
Output	Quarterly internal audit report; record of nonconformities with corrective actions; corrective action follow-up plan.
Step 9. Evaluation of internal and external customer satisfaction
Element	Content
Description	Measure the impact of the implemented improvements on customer satisfaction, meeting demand, and employees’ perceptions of the new working conditions.
Actions to be taken	Measure compliance with production schedules: compare actual production volumes to planned volumes; calculate the compliance rate; analyze the causes of non-compliance. Evaluate product quality: record customer complaints; compare the complaint rate with the previous period; evaluate the results of internal controls. Conduct a satisfaction survey among key customers. Conduct a perception survey among employees: improvements in working conditions, usefulness of training, clarity of procedures, and job motivation; compare results with the initial diagnostic survey. Analyze cost reductions: calculate savings from reduced raw material usage, revenue from value-added byproducts, and reduced disposal costs; compare benefits with implementation costs.
Inputs	Production plans and compliance records; complaint records; quality control results; list of key customers; data on raw material costs and waste disposal.
Techniques to be used	Analysis of plan compliance; satisfaction survey (Likert scale); complaint analysis; cost-benefit analysis; before-and-after comparison.
Frequency	Semiannual
Person in charge	Sales Department (external clients), Human Resources Department (internal clients), Finance Department (cost analysis).
Output	Semiannual satisfaction and compliance report; external and internal customer satisfaction index; analysis of cost reduction through the circular economy; recommendations for adjustments.

Source: Own elaboration

Phase IV: Corrective action and continuous improvement

Objective of this stage: To consolidate validated improvements, correct deviations, update system documentation, and plan new improvement cycles for replication across other product lines.

Table 4. Steps in stage 4

Step 10. Analysis of results and lessons learned
Element	Content
Description	Evaluate the results achieved against the established goals, identify the most effective actions, document the lessons learned, and analyze the causes of unresolved deviations.
Actions to be taken	Compare each indicator measured in Phase III with the PPC target; calculate the degree of compliance: (Achieved value / Target) × 100; classify indicators as met (≥ 95%), partially met (70-94%), or not met (< 70%). Identify success factors: analyze which actions generated the greatest positive impact; identify practices to maintain and reinforce; document success stories with quantified data. Analyze deviations: For indicators that were not met, conduct a root cause analysis; identify whether the causes are technical, organizational, human, or external; formulate corrective proposals for the next cycle. Document lessons learned: create a systematic record of what was done, what worked, what did not work, why, and what is recommended; share this information in a meeting with the staff involved; incorporate it into the best practices manual.
Inputs	Monthly indicator reports (Step 7); internal audit reports (Step 8); satisfaction and compliance report (Step 9); original PPC; incident logs during implementation.
Techniques to use	Gap analysis; root cause analysis (Ishikawa); lessons-learned technique (After Action Review); contribution analysis; multidisciplinary retrospective meeting.
Time	1 week
Person in charge	Board of Directors, with technical preparation by the Technical and Development Department and the quality specialist.
Output	Report evaluating results against goals; record of lessons learned; proposals for corrections for the next cycle; best practices manual (draft).
Step 11. Standardization and updating of procedures
Element	Content
Description	Incorporate validated improvements and successful practices into the official documentation of the Quality and Production Management System, ensuring their sustainability and replicability.
Actions to be taken	Update equipment technical data sheets: incorporate new, adjusted operating parameters; include preventive maintenance frequencies and procedures; update output quality specifications for each operation. Update Standard Operating Procedures (SOPs): draft or update SOPs to incorporate circular economy practices; include procedures for differentiated waste management in each operation; include procedures for filling out control forms; include procedures for responding to deviations from indicators. Update the QMS Procedures Manual: incorporate the circular improvement procedure as an official document; link it to other procedures in the system; establish an annual review. Provide training on updated procedures: design orientation sessions; administer comprehension assessments; make documentation available at reference points throughout the department.
Inputs	Results evaluation report (Step 10); current QMS Procedures Manual; equipment data sheets; current POE; applicable regulations (NC 108:2012, adapted ISO 9001).
Techniques to use	Technical drafting of procedures; peer review; document version control; group training sessions; comprehension assessment.
Time	2 weeks
Person in charge	Technical and Development Department, with support from the quality specialist and the standardization specialist.
Output	Updated equipment technical data sheets; updated and approved POE; updated QMS Procedures Manual; training log for new procedures; documentation available in the work area.
Step 12. Planning new improvement cycles and replication
Element	Content
Description	Identify new opportunities for circularity, evaluate the feasibility of replicating the procedure in other production lines, and formulate the improvement plan for the next PDCA cycle.
Actions to be taken	Identify new opportunities for circularity: evaluate low-investment technologies that have not yet been implemented (drying seeds for oil, small-scale biogas production, high-quality composting); assess technical and economic feasibility; prioritize based on impact and investment. Assess replicability to other production lines: analyze similarities and differences between tomato puree and other processes (mango milling, guava milling); identify necessary adjustments to the procedure; estimate resources and timelines; develop a sequential replication plan prioritizing the line with the greatest potential. Develop an improvement plan for the next cycle: define new objectives based on current results; incorporate opportunities and areas for replication; set more challenging goals; define new indicators if necessary; develop a timeline and assign responsibilities. Share results and projections: prepare an executive report for the Ministry of the Food Industry, Senior Business Management Organizations, CIGET, and the University of Pinar del Río; present at scientific or business forums if feasible; document the experience as a case study.
Inputs	Results evaluation report (Step 10); best practices manual (draft); technical information on new value-added technologies; process descriptions for other product lines; updated Development Strategy; current PCC guidelines.
Techniques to Use	Technical-economic feasibility analysis; process similarity analysis (comparison matrix); strategic planning (objectives tree); preparation of executive reports; stakeholder management.
Time	2 weeks
Person in charge	Board of Directors, with technical preparation by the Technical and Development Department.
Output	Improvement plan for the next PDCA cycle; plan for replication across other production lines; executive report on results and projections; documented case study for external dissemination.

Source: Own elaboration

Figure 1 shows the flowchart of the procedure for improving the recycling process on the company's tomato puree production line.

The flowchart represents a nonlinear management system based on the PDCA cycle, where the stages are interconnected through multiple feedback loops that ensure continuous process improvement. In the planning stage, the diagnosis of the material flow determines the identification of root causes, which in turn determine the quality of the Circular Improvement Plan, which can be adjusted based on management approval. During implementation, there is direct interaction between technological adjustments, the organization of the waste management system, and staff training, highlighting the critical relationship between technology and the human factor. In the control phase, performance indicators, internal audits, and satisfaction assessments serve as verification mechanisms that provide feedback to the implementation stage in the event of deviations or nonconformities. Finally, in the improvement stage, the analysis of results allows for the redefinition of causes and actions, while standardization consolidates successful practices and the planning of new cycles restarts the process, closing the system with a dynamic, adaptive, and sustainability-oriented approach.

Figure 1. Flowchart of the procedure for improving the production process
Source: Own elaboration

This flowchart represents the Circular Improvement Procedure applied to the tomato puree production process, structured according to the PDCA cycle in 4 stages with 12 steps:

• Stage I - Planning (Steps 1-3): The current material flow is characterized, the root causes of problems are identified, and the Circular Improvement Plan is designed, which must be approved by management.
• Stage II - Implementation (Steps 4-6): Critical technological operations are optimized; differentiated waste management is implemented along with a reorganization of the area; and staff are trained to operate under the circular approach.
• Stage III - Monitoring and Follow-Up (Steps 7-9): Circular performance indicators are measured, internal audits of the management system are conducted, and the satisfaction of internal and external customers is evaluated.
• Stage IV - Corrective Action and Continuous Improvement (Steps 10-12): Results and lessons learned are analyzed, procedures are standardized, and new improvement cycles are planned.

Each step includes decision points (yellow diamonds) that, if not met, trigger corrective actions (red boxes) through feedback loops. When new opportunities for improvement arise, the system restarts the PDCA cycle, thereby ensuring continuous improvement. Each stage generates documented outputs (flowcharts, matrices, reports, and documents) that support the traceability of the procedure.

Validation of the procedure

Validation was conducted using the Iadov technique, applied to 19 managers and specialists involved in the tomato puree production process. The questionnaire consisted of five questions -three closed-ended and two open-ended- structured in such a way that respondents could not perceive the logical relationship between them. The results were conclusive: 100% of respondents stated they were satisfied with the designed procedure, 96.15% said they liked the design very much, and 100% considered the tool to be useful and applicable in the company's real-world context. The calculated Group Satisfaction Index yielded a value of 0.942, falling within the range of maximum group satisfaction, which confirms the procedure's relevance, practical feasibility, and perceived effectiveness.

Among the aspects rated positively by the evaluators were: the potential for application to other production lines or companies in the sector; the positive impact on production efficiency, waste reduction, and sustainability; y improvements in process quality and decision-making; and the integration of management tools such as performance indicators, waste control, and organizational techniques (5S), which had not previously been applied systematically. These results are consistent with the findings of Raudales García et al. (2024), who identified that 34% of the organic waste generated by canning companies was suitable for recovery, although only 12% was actually reintegrated into production processes, and align with the need highlighted by Lieder and Rashid (2016) for a systemic approach that enables product redesign, innovation in business models, and the adoption of enabling technologies.

The research confirmed the existence of a clear contradiction between the linear production model implemented at "La Conchita" Vegetable Canning Company and the principles of the circular economy, manifested in the absence of waste management metrics, a lack of infrastructure for waste sorting and processing, technological limitations, economic constraints, and a lack of tools to identify waste levels -all of which lead to a systematic waste of raw materials.

A comprehensive assessment of the tomato puree production process, conducted through the triangulation of multiple sources and techniques, identified six fundamental causes of inefficiency: poor working conditions, difficulties in solid waste management, poorly trained staff, machinery in poor condition, demotivation and labor inefficiency, and low job content. The 80% loss coefficient quantified using the SGCC highlights the magnitude of the production waste.

The designed procedure constitutes an original methodological contribution by integrating -into a twelve-step operational sequence under the PDCA cycle framework- the diagnosis of material flow, differentiated waste management, human capital training, and the measurement of circular performance indicators, thereby addressing the methodological gap identified in the state of the art regarding the integration of operational diagnosis, process optimization, and waste valorization into a unified methodology.

Validation using the Iadov technique, with a Group Satisfaction Index of 0.942, confirms the procedure's contextual relevance, technical and economic feasibility, replicability, completeness, and operational clarity, as well as its perceived effectiveness from the perspective of those who directly interact with the production process. This strengthens confidence in its implementation and widespread adoption across other production lines in the Cuban agro-industrial sector.

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Conflict of interest

Authors declare that they have no conflicts of interest.

Authors' contribution

All the authors reviewed the writing of the manuscript and approve the version finally submitted.