The effect of washing for the shelf-life parameters of spinach (Spinacia oleracea L.)

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dc.contributor.advisorKaraffa, Erzsébet Mónika
dc.contributor.authorShahriyari Ansaroudi, Rana
dc.contributor.departmentDE--Mezőgazdaság- Élelmiszertudományi és Környezetgazdálkodási Kar
dc.date.accessioned2024-06-12T08:00:03Z
dc.date.available2024-06-12T08:00:03Z
dc.date.created2024-05-09
dc.description.abstractAs a member of the Goosefoot family, spinach (Spinacia oleraceae L.) is widely recognized for its vivid green foliage and multipurpose nature in the realm of food. It is highly regarded for its nutritional density, which comprises significant quantities of phytonutrients, vitamins, and minerals. The produce business commonly utilizes sodium hypochlorite or chlorine solutions as the primary disinfection agents. Nevertheless, they generate chlorinated by-products that have the potential to be harmful to people (Pahariya et al. 2022). So, the contemporary food industry's transition towards minimally processed ingredients has emphasized the criticality of prolonging the shelf life of spinach while preserving its nutritional value and freshness. Nevertheless, there are notable obstacles that have emerged regarding the presence of microorganisms, particularly those generated by harmful bacteria like Salmonella and Escherichia coli. The aim of this thesis was to assess the efficacy of using a 0.5% citric acid solution to wash spinach in order to reduce microbiological contamination and enhance shelf-life characteristics, therefore maintaining quality attributes during storage. By doing so, it attempts to fill important gaps in industry practices and consumer safety and offer empirical support for the implementation of sustainable preservation methods. Moreover, it addresses the changing demands of industry stakeholders and consumers. The research entailed the utilization of diverse techniques to prepare spinach leaves for microbial analysis. The leaves were washed with citric acid and sterile water, dried, and stored at different temperatures. Enumeration of yeast and molds, detection of E. coli and coliforms, and determination of the total microbial population comprised the microbial investigations. Total bacterial growth was determined using the pour plate method and PCA media culture; dishes containing fewer than 150 colonies were chosen for enumeration. whereas the spread-plate technique was utilized for determining yeast and mold content with DRBC media culture. the population of E. coli was determined using TBX media culture and the use of the pour plate method. The chlorophyll meter SPAD-502 was employed to determine the relative chlorophyll content of spinach. The TA.XTPlus Texture Analyzer was employed to ascertain the tensile strength and firmness of spinach leaves, attributes that are indicative of their freshness. Carotenoids, chlorophyll a, and chlorophyll b content were measured utilizing spectrophotometrically at wavelengths of 480, 647, and 664 nanometers. The outcomes of the data analysis, which was conducted with SPSS, were contrasted through a variety of tests like the Kruskall-Wallis test. The initial significant reduction in total microbial contamination was observed on day zero and also during storage until the 4th day, attributed to citric acid's antimicrobial properties. However, the efficacy of citric acid treatment declined over time, ultimately failing to have any noticeable effect on microorganisms by the seventh day of storage. Regarding yeast and mold content, the reduction in fungal contamination facilitated by citric acid treatment was at a significant level compared to both control and water-washed samples on the zero-day of analysis. However, the extent of this reduction fell short of one lg cfu/g, failing to achieve the requisite reduction to meet the accepted contamination level. However, this disinfection was effective only until the 4th day and then waned afterward. The study also found that citric acid could decrease E. coli contamination immediately after washing but the reduction is not significant. The disinfection effect of this organic acid on E. coli disappears during storage at 12°C. The presence of citric acid did not have a noteworthy impact on the SPAD value of leaves. However, when considering the influence of time and storage duration, increases in the SPAD value of spinach leaves were found. Both unwashed and cleansed samples exhibited a reduction in leaf elasticity throughout the storage period. Throughout the duration of storage, the control samples exhibited a substantial reduction in elasticity than citric-washed samples. Therefore, citric acid emerges as a prospective substitute technique for the cleansing and disinfection of spinach leaves. Carotenoid content increased continuously in the "unwashed" treatment group, suggesting that citric acid might also affect the storage stability of carotenoids. Regarding the discoveries regarding chlorophyll, no significant differences were observed among the control and treated samples during the study period and the full storage term. The average concentration of chlorophyll "b" in spinach leaves remained constant during storage, however, the trend varied for samples that were subjected to citric acid washing. This study provides a comprehensive analysis of the impact of citric acid treatment on the quality of spinach maintained at low temperatures. The analysis takes into account sensory qualities, biochemical composition, and microbiological contamination, resulting in a clear understanding of the many effects of citric acid treatment. The primary aim of this research study was to evaluate the antimicrobial effectiveness of citric acid against common microbial contaminants found in perishable agricultural products, such as E. coli, yeast, and viable bacterial count on spinach leaves. This assessment was conducted both immediately after washing and during a 7-day storage period at a temperature of 4°C. In general, citric acid exhibited satisfactory efficacy in regulating the overall microbial count, as well as yeast and fungi, in spinach samples during refrigerated storage (4±1 C for seven days). Nonetheless, at 12 °C, there was no significant reduction in E. coli. Furthermore, except for insignificant decrease of texture, there were no statistically significant distinctions or adverse effect observed in terms of sensory quality between samples treated with CA, control, and water-rinsed samples. Hence, a single-step cleansing process utilizing 0.5% citric acid (2 minutes at 25 degrees Celsius) proves to be an efficacious, viable, and organic produce-compatible disinfectant for spinach leaves. Moreover, it may serve as a substitute for their conventional cleaning and disinfection technique. The findings of our study indicate that washing methods and the condition of storing can affect its respiration rate, metabolic processes, tissue integrity, and sensory quality. However, it was found that using CA treatment can effectively control foodborne pathogens on fresh spinach leaves immediately following citric acid washing and can maintain its effectiveness for up to four days of storage without negatively impacting the quality of the spinach leaves (Zhou et al. 2023). To improve the effectiveness of citric acid in extending the freshness of spinach leaves, the study suggests implementing the following measures: concentration optimization, evaluation of pre-treatment methods, assessment of integrated approaches, analysis of microbial diversity, and consumer acceptability studies.
dc.description.correctorKE
dc.description.coursefood Safety and quality engineering
dc.description.degreeMSc/MA
dc.format.extent53
dc.identifier.urihttps://hdl.handle.net/2437/372445
dc.language.isoen
dc.rights.accessHozzáférhető a 2022 decemberi felsőoktatási törvénymódosítás értelmében.
dc.subjectspinach
dc.subjectalternative disinfection methods
dc.subjectE. coli
dc.subjectsensory attributes
dc.subjectshelf life
dc.subject.dspaceAgricultural Sciences
dc.titleThe effect of washing for the shelf-life parameters of spinach (Spinacia oleracea L.)
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