The effect of packaging treatment on the storage quality of minimally processed bunched onions

Gamma radiation processing for extending shelf-life and ensuring quality of minimally processed ready-to-eat onions

Onions are always in high demand owing to various culinary as well as health protective properties and these days there is increased consumer preference for ready-to-eat or ready-to-cook onions. In this context, the current study was aimed to extend the keeping quality of minimally processed onions for an extended period while ensuring microbial safety as well as sprouting inhibition through an integrated approach. The optimized combinatorial approach included gamma radiation treatment (Dmin60 Gy), minimal processing (de-skinning and scooping) and packaging in trays wrapped with polypropylene (PP; 10 µm thick) film followed by storage at low temperature (4-6 °C, relative humidity RH 65-70%). The parameters like shelf life, physico-chemical (colorimetry, moisture), organoleptic and nutritional properties were comprehensively assessed and found to be well retained up to 30 days with moisture loss of ≤ 5% and overall acceptability rating of 7 on 9-point hedonic scale. Microbiological analyses confirmed absence of Salmonella spp in these stored onions thus ensuring microbial safety. Nutritional profiling including carbohydrate, protein, fat, energy, and ash content revealed no significant change due to the processing as well as during storage. Thus, the radiation processing of freshly harvested bulbs followed by minimal processing, packing in formulated package and storage under low temperature conditions were found acceptable up to 30 days in the ready-to-eat form. Current findings provide credible evidences ascertaining extended shelf-life as well ensuring microbial safety of processed onions for commercial utilization by the food industries.

Single and Combined Effect of Mild-Heat Treatment and Alginate Coatings on Quality Preservation of Minimally Processed Bunching Green Onions

Bunching green onion is an Allium species that has been widely used in food flavorings and seasonings. This vegetable experiences a rapid loss of quality during storage due to physiological changes and microbial spoilage. In the current work, the single and combined effect of mild-heat treatment (55 °C for 60 s) and alginate edible coatings on the quality preservation of minimally processed bunching green onions was studied. Control and treated samples were stored at 4 °C for 15 days and examined periodically in terms of their respiration rate, weight loss, pH, soluble solids content, firmness, total polyphenol content, antioxidant activity, microbial count, decay ratio, and overall visual quality. The results showed that the combination of mild heat and alginate edible coatings was the most effective approach to slow down the respiration rate and the incidence of decay in the minimally processed bunching green onions. In addition, the treatments with alginate coating alone or combined with mild-heat treatment showed the best performance for maintaining the overall visual quality of the products during the storage.

Effects of long-term controlled atmosphere storage, minimal processing, and packaging on quality attributes of calçots (Allium cepa L.)

Calçots are the immature floral stems of the second-year onion (Allium cepa L.) resprouts. Modified atmosphere packaging or vacuum packaging are suitable alternatives to preserve fresh-cut vegetables. The objective of this study was to evaluate the effect of postharvest storage time of raw vegetable stored under controlled atmosphere and used packaging system after minimal processing on the quality of fresh-cut calçots. Calçots used for minimal processing were stored under 1.0 kPa O₂ + 2.0 kPa CO₂ at 1 ℃ for 30 and 60 days. Fresh-cut calçots were packaged using passive modified atmosphere packaging or vacuum packaging and were stored at 4 ℃ for 15 days. Calçots stored under controlled atmosphere for 30 days presented better retention of quality and in turn, being more suitable for minimally processing. Vacuum packaging preserved the physicochemical quality of fresh-cut calçots better after 15 days. Mesophilic aerobic counts were also higher in fresh-cut calçots stored under modified atmosphere packaging, but all counts were below the recommended limits during and at the end of their shelf-life (15 days). The most suitable conservation strategy might be to store whole calçots under controlled atmosphere for 30 days and after minimally processing, packaged under vacuum in order to extend the shelf-life of fresh-cut calçots.

Influence of vacuum packaging and long term storage on quality of whole chilli (Capsicum annuum L.)

Investigations were carried out to study the influence of vacuum packaging and long term storage on quality in red chilli. Chilli fruits were stored in vacuum packed and jute bags at two moisture levels (10 % and 12 %) in room and cold environments under both light and dark conditions for a period of 24 months. During storage period, average room and cool chamber temperatures were 25 ± 2 °C and 4 ± 1 °C, respectively. Changes of moisture (Halogen moisture analyzer), capsaicin (HPLC-UV), oleoresin and total extractable colour (spectrophotometer) were analyzed at 3 months interval up to 12 months and 6 months interval from 12 to 24 months. Statistical analysis (ANOVA) and Duncan's test were applied to the analytical data to evaluate the effect of treatments applied. It was observed that the vacuum packed chillies under cold storage were found to have the least per cent decline in various quality parameters. Chillies with 12 % moisture and stored in vacuum packaged bags recorded better quality parameters over 10 % moisture.

Influence of vacuum packaging on seed quality and mineral contents in chilli (Capsicum annuum L.)

Studies were carried out to find out the influence of vacuum packaging on physical parameters of whole chilli and biochemical constituents in chilli seeds. Chilli fruits were stored in vacuum packed and jute bags stored at room temperature (25 ± 2 °C), cold storage (4 ± 1 °C) under both light and dark conditions for a period of 24 months. At the end of the storage period, seeds were separated from fruits and various parameters viz., moisture content, capsaicin content, ascorbic acid, carbohydrates, protein and mineral elements like Fe, P, Na and K were analyzed. It was observed that the samples stored in vacuum packed bags maintained the quality with least deterioration in all the quality parameters compared to samples stored in jute bags.