• Food Science and Preservation
• /
• v.24 no.2
• /
• pp.159-167
• /
• 2017

This study was investigated the effects of maintaining the freshness and stabilization of supply and demand for lettuce (Lactuca sativa L.) by packaging methods in summer. Post-harvest lettuces were packaged by corrugated box, polypropylene (P) box, and individual wrapping using polyvinyl chloride (PVC) film. Then, the lettuce samples were stored at $2^{\circ}C$ and evaluated the change of quality during storage. The lettuces wrapped individually with PVC film had lower weight loss rate, color change, and browning index compared to lettuces packaged by corrugated box and P box. The SPAD value and hardness were higher in lettuces wrapped individually with PVC film than other packaging methods. The lettuces wrapped individually with PVC film were showed the highest total phenolic contents and DPPH radical scavenging activity, but there were no significantly differences by packaging methods. The lettuces packaged by corrugated box were showed the inside browning after 14 days. However, the lettuces wrapped individually with PVC film were showed the best appearance. Therefore, the packaging method of wrapped individually with PVC film were effective in maintaining the freshness during 21 days and helpful for the stabilization of supply and demand for lettuce in summer.

• Korean Journal of Plant Resources
• /
• v.24 no.1
• /
• pp.17-22
• /
• 2011

This study was for developing leaf chlorophyll mutant cultivars of Cymbidium goeringii by ethyl-methanesulfonate(EMS) treatment. Chlorophyll mutant rhizomes were easily produced by 0.2% EMS treatment in this genus. Among the mutants, they became dark brown about 50% of the rhizomes. When the dark-brown rhizomes were cultured in a solidified MS medium, new rhizomes were formed from part of the old ones. Chlorophyll mutant rhizomes were obtained from subcultured meristem tissues of newly-formed rhizomes. The rhizomes were cut and subcultured for a year and then became mutant plants. As the results, they produced 4 kinds of leaf mutant cultivars; zigzag-striped, comb-striped, net-striped, and dwarf types, indicating that the EMS treatment in the rhizome could produce versatile leaf chlorophyll regulating mutants. These results suggest that our method is useful for developing leaf mutant cultivars of this planta which they are estimated as higher commercial values.

• Korean Journal of Agricultural Science
• /
• v.4 no.1
• /
• pp.105-111
• /
• 1977

Inhibitory effect of sugars on lipase production by Trichosporon cutaneum was observed in the previous study (Kim, 1972), and inhibition was distinctive by the addition of glucose, fructose, mannose, xylose and arabinose to the soybean meal medium among various carbon sources. These experiments were carried out to study the effect of sugars on cell growth and lipase production by the strain using the soybean extracts liquid medium under a shaking culture system. Changes in color and pH of the medium were caused by heat sterilization when various sugars were added. To elucidate the possible effect of these coloring matters on lipase production and cell growth: changes in pH of the culture, cell concentration and level of the enzyme activities were determined when the culture was grown for 48 hours at $30^{\circ}C$ on a reciprocal shaker. The results obtained were as follows: 1. Density of brownish color which formed during heat sterilization was varied with the variety of sugar used, ie, strong in pentose such as xylose: weak in hexose such as galactose, mannose, glucose: very weak in disaccharide such as maltose, sucrose. When the color density was stronger, decrease in pH after sterilization was marked. 2. Cell growth and lipase production was not so effect by the coloring matters as by sugars. 3. The more the cell mass of the culture, the lower the level of lipase production in the culture supernatant. 4. Among the sugars which caused the distinctive inhibition of lipase production, a slight relief of inhibition was noticed by the addition of xylose, whereas the cell growth was repressed. 5. When cell growth was better, decrease in pH of the medium was greater during cultivation.

• Korean Journal of Food Science and Technology
• /
• v.28 no.6
• /
• pp.1126-1134
• /
• 1996

The physical characteristics changes of carrots during drying were studied to minimize the quality degradation by applying improved drying process and pretreatment method. Physico-chemical properties of the product were analyzed, and then, drying mechanisms were explained by diffusion coefficients and drying models. In hot air drying process, the drying and rehydration efficiencies were high at low relative humidity and high temperature. Browning degree and specific volume also showed similar trend to drying efficiency. Diffusion coefficient, which describes moisture transfer, was also high at low relative humidity and at high temperature. It was verified using. Arrhenius equation that drying process was influenced by temperature. It was also observed during experiment that temperature changes were more effective in drying than relative humidity changes. Quadratic model was the most fittable in explaining the process. As a result of analyzing the experimental data with respect to the drying time, the contents of carotene and moisture could be modeled as a polynomial. As the air velocity increased, drying performance and rehydration efficiency increased.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.1
• /
• pp.7-12
• /
• 1994

The kinetics of browning reaction of dried shrimp powder samples were investigated during storage. The temperature conditions of the ding process were $25^{\circ}C\;and\;45^{\circ}C$, and the samples were stored at water activity ($a_w$) of 0.33, 0.44, 0.52, 0.65 and temperatures of $35^{\circ}C,\;45^{\circ}C,\;55^{\circ}C$ and temperature fluctuations between $33^{\circ}C\;and\;55^{\circ}C$. When the shrimp was dried at $25^{\circ}C$ the activation energies obtained from the Arrhenius plot ranged from 13.57 to 14.33 kcal/mol. From these energies of activation, the $Q_{10}$ values at $25^{\circ}C$ showed 1.93 to 2.00. In the case of drying at $45^{\circ}C$ the activation energies were $13.12{\sim}13.61\;kcal/mol$ and $Q_{10}$ values were $1.89{\sim}1.93$, respectively. In addition, a storage study under square-wave fluctuating temperature conditions was carried out by varying the shrimp sample temperature between $35^{\circ}C\;and\;55^{\circ}C$ within 7 days regular fluctuation cycle. The data obtained from the fluctuating temperature storage study will be used in the prediction of shelf-lives. The shelf-lives assessed at $25^{\circ}C$ from the accelerated shelf-life tests ranged from 4 days at aw 0.65 to 139 days at aw 0.33.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.10
• /
• pp.1178-1185
• /
• 2017

Two types of kimchi with a different total acidity (TA, 0.75% or 1.19%) were heated at $100^{\circ}C$ for up to 60 min to develop a gratin added with heated-kimchi. Their browning index and color intensity increased with increasing heating time, which was more apparent for the kimchi with the higher TA. This was attributed to the Maillard reaction facilitated at a higher heat intensity and by the smaller fermentation products. The same tendency was also observed for the antioxidant activities determined by the total reducing capacity, metal-chelating activity, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. In particular, heating kimchi at $100^{\circ}C$ only for 10 min increased the activities significantly. Therefore, the heated-kimchi was added to gratin at 20%. With the addition, the dietary fiber, ${\gamma}-aminobutyric$ acid (GABA) and ornithine contents in the gratin were increased appreciably (P<0.01). Nevertheless, there was little change in its salinity. The antioxidant activities of the gratin were significantly (P<0.001) higher than the control gratin without kimchi, with DPPH radical scavenging activity being 3.6 times higher. The results suggest that the functionality of kimchi could be effectually added to gratin even after heat treatment.

• Culinary science and hospitality research
• /
• v.12 no.4 s.31
• /
• pp.225-235
• /
• 2006

This study was carried out to investigate the optimum conditions for the preparation of natto(unripe Chungkukjang) using Sowonkong(small soybeans) and Bacillus subtilis KCCM 11315. The changes in the contents of amino-type nitrogen, ammonia-type nitrogen, total acidity and total sugar, and those in the pH, browning materials and microbial growth were determined during fermentation and aging of natto(unripe Chungkukjang). The amounts of amino-type nitrogen and ammonia-type nitrogen were increased gradually during the fermentation at $40^{\circ}C$ for 72 hours, but those of total acidity and total sugar were decreased. The pH was gradually alkalized, and more water soluble browning materials were produced during fermentation. The number of viable cells was the highest at the 36 hours of fermentation. The content of ammonia-type nitrogen was significantly decreased during aging at $4^{\circ}C$ for 48 hours. In view of the results as above, it seems possible to conclude that the natto(unripe Chungkukjang) fermented by Bacillus subtilis KCCM 11315 at $40^{\circ}C$ for 36 hours and then aged at $4^{\circ}C$ for 48 hours was suitable for manufacturing natto(unripe Chungkukjang).

• Food Science and Preservation
• /
• v.23 no.5
• /
• pp.689-695
• /
• 2016

In this study, the drying characteristics of medicinal (Ganoderma lucidum, Phellinus linteus) and edible (Pleurotus eryngii, Lentinus edodes) mushrooms were investigated. Their shrinkage ratios, Hunter's color values, and rehydration ratios were evaluated. Mushrooms were cut with rectangular (1 cm) and square ($1{\times}1cm$) shapes, and dried in the room temperature and at $50^{\circ}C$ and $70^{\circ}C$ using hot-air dryer. Initial moisture contents of edible mushrooms were higher than those of medicinal mushrooms, whereas final moisture contents were vice versa. Drying rate was the highest when drying at $70^{\circ}C$ (p<0.05). Moreover the drying rate of square slices was higher than that of rectangular slices (p<0.05). The shrinkage ratios of both medicinal mushrooms and edible mushrooms were the least when drying at $50^{\circ}C$ and $70^{\circ}C$, respectively (p<0.05). The changes of color values were less in the medicinal mushrooms dried in the room temperature than in the hot-air dried medicinal mushrooms (p<0.05). However, in case of edible mushrooms, the changes of color values were less in the hot-air dried mushrooms (p<0.05). Rehydration ratios of medicinal mushrooms dried at $50^{\circ}C$ was the highest (p<0.05). In contrast, rehydration ratios of edible mushrooms was the highest when drying in the room temperature (p<0.05). Thus, the hot-air drying at $50^{\circ}C$ would be suggested as the efficient drying method for both medicinal mushrooms and edible mushrooms.

• Korean Journal of Food Science and Technology
• /
• v.31 no.6
• /
• pp.1447-1452
• /
• 1999

Lipid-related components were comparatively investigated for white ginseng when exposed to both phosphine fumigation and gamma irradiation at 5 kGy or less, which were found effective for improving its biological quality. Fumigation resulted in the increase in pH of the sample, and thereafter it showed a decreasing tendency in all samples during storage for 6 months at ambient $(20^{circ}C/70%\;RH)$ and accelerated $(40^{\circ}C/90%\;RH)$ conditions. The severe conditions led to an apparent browning of the stored samples without significant differences among them, while the sample stored at ambient condition showed negligible changes in its color up to 6 months. The development of browning in the stored sample was in proportional to hydrogen donating ability of the corresponding sample extract. TBA value increased by gamma irradiation gradually decreased with storage time, showing similar values to that of other samples, whereas carbonyl value gradually increased in all samples. Both fumigation and gamma irradiation caused negligible changes in fatty acid composition; however, a partial increase in saturated fatty acid composition and some decrease in polyunsaturated ones were observed with the storage time.

• Korean Journal of Food Science and Technology
• /
• v.36 no.2
• /
• pp.283-287
• /
• 2004

Persimmons suffer from such physiological disorders as flesh softening, peel blackening, and flesh browning, which occur rapidly particularly when exposed to ambient temperature after storage at low temperature, In this study causes of these disorders were examined in terms of respiration and ethylene production of the fruits. Jelly-like flesh softening, considered as symptom of chilling injury, rapidly developed within 3 days of exposure to ambient temperature without modified atmosphere (MA) packaging after low temperature storage. Disorder development was more suppressed at $30^{\circ}C$ than at $20^{\circ}C$; such temperature dependence is closely connected to ethylene production rate of fruits at both temperatures. Inhibition of ethylene production through MA packaging effectively reduced disorder development, which indicates ethylene production is closely related to jelly-like flesh softening disorder. Development of black-staining on peels occurs in fruits exposed directly to ambient temperature, but not in those packaged with thick PE-film. Flesh browning developed only under anaerobic respiration condition of high temperature and MA packaging with thick PE film, and occurred at quick reduction of available oxygen inside MA package at high temperature.