QUALITY CHANGES IN FRESH-CUT SPINACH (SPINACIA OLERACEA) UNDER MODIFIED ATMOSPHERES WITH PERFORATIONS

Effects of washing with boric acid solutions on residual boric acid content, microbiological load, and quality of fresh-cut spinach

Insufficient disinfection of fresh-cut spinach poses significant health risks, along with potential issues like odor, color changes, and softening during short-term storage. To address these challenges, boric acid solutions were explored as an alternative to chlorine washes, which are known to produce toxic compounds. Among various concentrations, 1 % boric acid exhibited the most effective microbial inactivation, leading to substantial reductions in total mesophilic aerobic bacteria, total yeast and mold, and Enterobacteriaceae counts, with reductions of 1.64, 1.38, and 1.77 logs, respectively. Additionally, washing spinach leaves with this solution for 1 min maintained quality parameters, with enhanced antioxidant activity (55.26 mg kg-1 Trolox equivalent), increased total phenolic content (1214.06 mg kg-1 gallic acid equivalent), retention of chlorophyll a (839.16 mg kg-1), chlorophyll b (539.61 mg kg-1) and ascorbic acid content (264.72 mg kg-1). Mechanical properties such as puncture strength (1.81 N) and puncture distance (52.78 mm) also showed favorable outcomes, alongside optimal moisture content at 89.81 %. Notably, residual boric acid content was lowest in spinach leaves (1252.49 mg kg-1) and highest in the wash water (53.88 mg kg-1) after treatment. Scanning electron microscopy images demonstrated maintained tissue integrity, while Hunter Lab readings indicated minimal color changes post-washing. Additionally, sensory evaluations and various physicochemical analyses further supported the efficacy of boric acid washing. Consequently, washing spinach leaves with a 1 % boric acid solution for 1 min yielded favorable results across multiple quality parameters. These findings suggest the potential of boric acid as a safe and effective alternative disinfectant in the fresh-cut produce industry, highlighting its practical implications for food safety and quality. Future research should focus on exploring long-term effects and optimizing washing protocols for broader applications.

Performance Evaluation of Mobile Liquid Cooled Thermoelectric Refrigeration System for Storage-Cum-Transportation of Fruits and Vegetables

The performance of a liquid-cooled thermoelectric refrigeration (LCTR) system for the storage of summer fruits and vegetables, viz., bitter gourd, okra, mango, and papaya, indicated notable results for physiological loss in weight, firmness, and colour values and overall acceptability of the crop. The LCTR system significantly reduced (p < 0.0001) the physiological loss in weight (PLW) of bitter gourd, okra, mango, and papaya to 11.51%, 10.99%, 12.29%, and 19.17%, respectively, compared to conventional ambient storage of the crop. A lesser change in colour was observed for the crop subjected to LCTR, recording 14.04, 11.46, 16.41, and 23.68 for bitter gourd, okra, mango, and papaya, respectively. All the crops witnessed no significant effect (p < 0.0001) on the quality attributes of the crop stored in LCTR and a vapour compression refrigeration system. LCTR enabled a pronounced increment in the shelf life of bitter gourd, okra, mango, and papaya by 7, 8, 10, and 13 days, respectively, compared to storage at ambient conditions. The invention provides a mobile thermoelectric refrigeration system useful for marketing fruits and vegetables efficiently. The system is economical, has a higher coefficient of performance (0.85) compared to the coefficient of performance (COP) of the existing thermoelectric refrigeration system, and maintains the freshness and quality of perishable agricultural produce during marketing and transportation.

Modified Atmosphere Packaging and Dark/Light Refrigerated Storage in Green Leafy Vegetables Have an Impact on Nutritional Value

The consumption of zeaxanthin (Z) through a vegetable-rich diet is recommended to reduce the progression of age-related macular degeneration. Due to Z's intrinsic dynamic character that results from its participation in the photoprotective xanthophyll cycle involving the carotenoids violaxanthin, antheraxanthin and zeaxanthin (VAZ), post-harvest handling practices and storage usually retain low amounts of this bioactive compound (compared to the rest of phytochemicals that are, in general, more stable). Thus, the aim of this work was to investigate in important consumed leafy vegetables the effects of different storage conditions on carotenoids (mainly Z) including i) packaging under three modified atmospheres (MAs), ii) light refrigerated supermarket storage and iii) dark refrigerated domestic storage. The results showed that an MA with low O₂ and high CO₂ enhanced the Z content under light. Moreover, both light and dark refrigerated storage showed dynamic and circadian pigment changes that enhanced the total VAZ pool. These results can contribute to generating practical recommendations for industries, supermarkets, and consumers when high Z content is a nutritional target.

Biodegradable PLA (polylactic acid) hinged trays keep quality of fresh-cut and cooked spinach

This work examines the effects of packaging using two different polymeric trays with hinged lids, polyethylene terephthalate (PET) and polylactic acid (PLA), on fresh-cut and cooked spinach (Spinacia oleracea). Samples were stored in a cold room for 16 days at 4 °C. Chemical (total pigments, total polyphenols, ascorbic acid, antioxidant activity), physical (water activity), technological (colour evaluation), sensorial (aroma, visual appearance and water accumulation) and microbial (total aerobic mesophilic and psychrotrophic counts) parameters were tested. Both polymeric trays maintained the overall quality of fresh spinach for 6 days but spinach stored in PLA trays maintained its flavour longer. A significant increase in total polyphenols, antiradical activity, total carotenoids as well as a decrease in ascorbic acid in fresh spinach was observed in the first 3 days of storage in both samples. Unfortunately, the PLA package accumulated condensed water. The total microbial load of fresh-cut spinach reached about 6.3-7.3 log CFU g(-1) within 8 days. Cooked spinach packed in PLA and PET polymeric hinged trays showed the same behaviour as fresh spinach in terms of quality and shelf life. In conclusion, PLA plastic hinged trays can be used for packaging fresh-cut and cooked cut spinach, but the problem of condensed water must be solved.

Effect of modified atmosphere packaging on the quality and bioactive compounds of Chinese cabbage (Brasicca rapa L. ssp. chinensis)

BACKGROUND

The perishability of Brassica chinensis poses a major challenge to distribution and marketing. The aim of this work was to select a suitable modified atmosphere packaging to retain the overall quality and bioactive compounds during storage.

RESULTS

Four types of biorientated polypropylene packaging (BOPP)--BOPP03, BOPP04, BOPP05 and BOPP06--with different perforations were evaluated regarding the maintenance of quality parameters (weight loss, leaf yellowing, colour L*, C*, h°), decay, chlorophyll a, chlorophyll b, bioactive compounds (carotenoids, ascorbic acid, total phenolic compounds), antioxidant scavenging activity, overall appearance and odour evaluation, at 10°C at 2, 4, 6, 8 and 10 days. Leaves were packed in BOPP (two 2-mm holes) and packed and unpacked leaves were included for comparison. The modified atmosphere created (2% O2 and 7% CO2) inside the BOPP05 reduced leaf yellowing (higher h°), improved the overall appearance with acceptable odour, moderately maintained chlorophyll a and b, bioactive compounds and antioxidant scavenging activity, and remained marketable for up to 10 days at 10°C. Gas composition within the packages influenced the retention of bioactive compounds and overall quality.

CONCLUSION

Application of BOPP05 is a promising method for extending the shelf life of B. chinensis leaves in order to promote its utilisation and commercialisation via urban fresh-produce markets.