• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.179-184
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• 1998

As a way of mass process of onion, Allium cepa L., the oleoresin decompressed and concentrated is an alternative process to minimize lowering in the quality of onion during storage, to improve the original flavor and taste, and to increase variety as processing aids. This study was performed to investigate on the quality stability during storage of oleoresin. Oleoresin product was manufactured by mixing a concentration of onion juice and ethanol extract homogenously, emulsified by an additional 2% PGDR(polyglycerol condensed ricinoleate) and 1% cysteine. During 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$ the total sugar content in oleoresin product was very stable, and absorbances at 420nm as browning reaction index were 0.38, 1.53 and 3.32, respectively, addition of 1% cysteine retarded the browning reaction effectively. When oleoresin product was centrifuged(2000$\times$G, 60 minutes), the volumes of emulsion level without separation were 96.8%, 94.1% and 9.06%, respectively during 20 days, 40 days and 60 days storage at 5$^{\circ}C$, and those during 60 days storage at $25^{\circ}C$ and 4$0^{\circ}C$ were appeared to be 83.2% and 75.4%. Showing lower level as increasing storage temperature. Antioxidant indexes(AI) of soybean oil added 1% oleoresin without storage and 0.02% BHA were 1.39 and 1.72. The former showed 80.8% antioxidant activity on induction time extension effect of the latter. Antioxidant indexes of oleoresin decreased slightly as increasing storage temperature and were 1.37, 1.30 and 1.08. Total pyruvate contents were 89.9%, 79.7% and 65.2%, respectively during 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$. Rate constant, Q10 value and activation energy were 1.381~4.735 mmol/$\ell$.hr, 1.537~1.694 and 11.649 ㎉/g mole for the reduction of pyruvates in the range of storage temperatures during oleoresin storage.

• Food Science and Preservation
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• v.30 no.5
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• pp.833-846
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• 2023

Onions are essential vegetables for Koreans' diet and have various physiological activities. However, problems arise every year due to the imbalance between production and demand. Therefore, in this study, nutritional and functional components, and antioxidant activity were analyzed for each growth period in order to utilize onions at the disposal period. Whole onions harvested before June showed higher values of general ingredients, inorganic ingredients, organic acids, spiraeoside, quercetin, total chlorophyll, and antioxidant activity than bulbs harvested in June. On the other hand, the free sugar content was higher in the bulb of the harvest season in June than in whole onions. The total thiosulfinate content was similar to that of whole onions and bulbs in the early stages of growth. In addition, as a result of comparing the flavonoid compound and antioxidant activity of each onion variety, whole onions harvested at 25 weeks were higher in content than onion bulbs harvested in June. In conclusion, onions before the harvest season in June had excellent utilization value as food. Harvesting before 21 weeks is desirable for growing onions with excellent nutritional value, while harvesting after 23 weeks is recommended for excellent functional components and antioxidant activity in onions.

• Food Science and Preservation
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• v.23 no.5
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• pp.623-630
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• 2016

Inappropriate storage of fresh-cut onions may result in losses of good quality. To understand storage conditions for shelf-life and quality of fresh-cut onions, The effect of packing type and storage temperature on the quality of fresh-cut onions was evaluated. Onions stored at $0^{\circ}C$ for 2 months were peeled off after removing root and shoot parts. Each three peeled onions were packed in a polyethylene film (PE, $50{\mu}m$) or in a polyethylene/polypropylene film (PE/PP, $100{\mu}m$) with vacuum treatment (70 cmHg) and stored at different temperatures (4, and $10^{\circ}C$) for 21 days. The following analyses were examined to evaluate the quality of fresh-cut onions: microbial population, surface color, titratable acidity and pH, respiration rate, and sensory quality. Fresh-cut onions stored at $4^{\circ}C$ showed less aerobic and coliform bacterial population than those stored at $10^{\circ}C$ during observation periods. Fungal populations of fresh-cut onions packed in PE film stored at $10^{\circ}C$ increased significantly after 13 days. E. coli was not detected in all treatments during whole storage periods. Surface colors of fresh-cut onions were not affected by packing type and storage temperature, however, color difference (${\Delta}E$) of fresh-cut onions in PE/PP film stored at $10^{\circ}C$ was significantly higher than those of other treatments. Titratable acidity of fresh-cut onions was not affected by packing type and storage temperature. However, pH of fresh-cut onions packed in PE film stored at $10^{\circ}C$ increased gradually over the whole storage period. Fresh-cut onions packed in PE film showed higher $CO_2$ and less $O_2$ concentrations at $10^{\circ}C$ than those at $4^{\circ}C$. The sensory quality of fresh-cut onions was significantly affected by packing type and storage temperature after 13 days. Particularly, vacuum treatment in PE/PP film showed better sensory quality than that of PE film package at the same storage temperature. It was concluded that vacuum treatment and storage at $4^{\circ}C$ could be effective to prolong the quality of fresh-cut onions up to 21 days.