• Horticultural Science & Technology
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• v.32 no.3
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• pp.353-358
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• 2014

Hot water dipping test was conducted for chicon to restrict red discoloration of its basal part which impairs the product value during sales. Hot water dipping treatment was given to chicon for 4 min and for 8 min at $38^{\circ}C$ and for 2 min and 4 min at $42^{\circ}C$, and for 1 min and 2 min at $45^{\circ}C$, along with control (for one min at $20^{\circ}C$). The red discoloration indices of basal part of chicon during sensory evaluation on the sixth day of storage under the storage temperature at $10^{\circ}C$ was lower at $42^{\circ}C$ for 2 min, $42^{\circ}C$ for 4 min and $45^{\circ}C$ for 1 min treatments. The color change value of the basal part in chicon measured by colorimeter showed that the lowest ${\Delta}a^*$ and ${\Delta}h$ were maintained in the basal part of chicon treated at $42^{\circ}C$ for 2 min. Whereas, color changes in $42^{\circ}C$ for 2 min and $45^{\circ}C$ for 1 min treatments were significantly low as compared with that of control. The contents of total phenolic compounds which are the substances that cause red discoloration of basal part in chicon were lowest at $42^{\circ}C$ for 2 min, $42^{\circ}C$ for 4 min and $45^{\circ}C$ for 1 min treatments. The activity of phenylalanine ammonia lyase (PAL) resposible for in the synthesis of phenolic substances was the least in $42^{\circ}C$ for 2 min treatment. Whereas, PAL activity of the chicons treated a t $42^{\circ}C$ for 2 min and at $45^{\circ}C$ for 1 min were significantly lower than that of control. However, red discoloration was progressed as similar level with that of control in the basal part of chicon at $45^{\circ}C$ for 2 min. The contents of total phenolic compounds and PAL activity in this treatment were not significantly different from those in control. The polyphenol oxidase (PPO) activity which causes red discoloration of cut tissues was low in all the treatments including $42^{\circ}C$ and $45^{\circ}C$ treatment at which no inhibition effects of the red discoloration of basal part of chicon were observed. When the correlation coefficient between each investigated index was tested, most of them showed high correlation except the PPO activity and particularly and the red discoloration index and sensory evaluation ${\Delta}h$ values, and PAL activity and total phenolic compounds content were $r=0.927^{**}$, and $r=0.942^{**}$, respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.47-47
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• 2003

Plant growth promoting rhizobacteria (PGPR) have been shown to suppress phytopthora blight. This suppression has been related to both microbial antagonism and induced resistance. The PGPR isolates were screened by dual culture plate method and most of the isolates were showed varyinglevels of antagonism. Among the PGPR isolates pyoverdin, pyochelin and salicylic acid producing strains showed the maximum inhibition of mycelial growth of Phytophthora capsici and increased plant growth promotion in red pepper. PGPR isolatesfurther analysed for its ability to induce production of defence related enzymes and chemicals. The activities such as Phenyle alanin ammonia lyase (PAL), Peroxidase (PO), Polyphenol oxidase (PPO) and accumulation of phenolics were observed in PGPR pretreated red pepper plants challenged with Phytophthora capsici. The present study shows that an addition of direct antagonism and plant growth promotion, induction of defense related enzymes involved to enhance resistance against invasion of P. capsici in red pepper.

• Preventive Nutrition and Food Science
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• v.17 no.3
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• pp.210-216
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• 2012

The use of suitable sanitizers can increase the quality of fresh-cut produce and reduce the risk of foodborne illnesses. The objective of this study was to compare the washing effects of 100 mg/L sodium hypochlorite (SH) and 500 mg/L acidified sodium chlorite (ASC) on the prevention of enzymatic browning and the growth of microbial populations, including aerobic plate counts, E. coli, and coliforms, throughout storage at $4^{\circ}C$ and $10^{\circ}C$. Fresh-cut zucchini, cucumbers, green bell peppers, and root vegetables such as potatoes, sweet potatoes, carrots, and radishes were used. Compared to SH washing, ASC washing significantly (p<0.05) reduced microbial contamination on the fresh-cut produce and prevented browning of fresh-cut potatoes and sweet potatoes during storage. More effective inhibition of aerobic plate counts and coliforms growth was observed on fresh-cut produce treated with ASC during storage at $10^{\circ}C$. Polyphenol oxidase (PPO) activity of fresh-cut potatoes and sweet potatoes was more effectively inhibited after washing with ASC. The use of 500 mg/L ASC can provide effective antimicrobial and anti-browning treatments of fresh-cut produce, including processed root vegetables.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1417-1422
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• 2009

This study was conducted to investigate the effect of ultrasound with ascorbic acid on the quality of fresh-cut apples. Prepared apple cubes were dipped in distilled water (US) or in 1% ascorbic acid solution (AS), both were treated with ultrasound at 40 kHz, while the other sample was just dipped in 1% ascorbic acid solution for 1 min (AA). All samples were stored at $4^{\circ}C$ for 12 days. AS treatment had an effect on apple cube color as indicated by its significantly higher L values and lower ${\Delta}E$ value whereas AA- and US-treated samples showed a considerable browning. Higher inhibition rate on browning and polyphenol oxidase (PPO) activity of 46 and 98%, respectively, were observed after AS treatment. The highest total phenolic content of AS-treated samples was shown during whole storage periods. This investigation revealed that the use of ultrasound in combination with ascorbic acid had a positive effect on quality maintaining of fresh-cut apples.

• Food Science and Preservation
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• v.10 no.1
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• pp.11-15
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• 2003

Various quality characteristics of minimally processed mushroom were measured to select appropriate browning inhibitor. The treatment of extracts from Asparagi radix, cassia and kiwi on mushrooms have a high effectiveness like ascorbic acid or cysteine, known as a good chemical antibrowning agent. As a results of physical quality characteristics of minimally processed mushroom during storage, 1% cysteine and Asparagi radix were highly effective on degree of browning. Total phenol content and polyphenol oxidase activity showed slight differences among the mushroom treated with each browning inhibitors, but it has gradually increased during storage. Thus, these results suggest browning inhibitors from natural materials can be alternatives to prevent browning on mushrooms instead of chemical browning inhibitors including ascorbic acid or cysteine, has been widely used for antibrowning agent.

• Food Science and Preservation
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• v.19 no.3
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• pp.323-327
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• 2012

The effects of ultrasound and ascorbic acid cotreatment on the browning inhibition and microbial growth of fresh-cut Tsugaru apples were investigated. The prepared samples were dipped in distilled water (Cont) or 1% (w/v) ascorbic acid solution (AA) and were then ultrasonicated in distilled water (US) or 1% (w/v) ascorbic acid solution (AA+US). The samples were then packed in a 0.04mm polypropylene bag ($20{\times}15$ cm) and were stored at $10^{\circ}C$ for eight days. The AA+US treated samples showed high $L^*$ and low $a^*$, $b^*$ values as well as inactivated PPO activity. The growth of the total aerobic bacteria also inhibited the AA+US treated samples more. The physicochemical properties were not different among all the samples. It was demonstrated in this paper that the ultrasonication treatment with ascorbic acid prevented the enzymatic browning of and microbial growth in fresh-cut Tsugaru apples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.2
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• pp.158-164
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• 1986

Polyphenol oxidase in apple (Golden Delicious) was extracted, partially purified and its properties were found as follows; Polyphenol oxidase showed optimum pH for activity at 6.5 and optimum temperature at $30^{\circ}C$ and high affinity to o-diphenol compounds. Cysteine, ascorbic acid and sodium metabisulfite appeared to be most effective inhibitors. EDTA showed a slight inhibition. During the enzyme was kept in test tube at $4^{\circ}C\;and\;20^{\circ}C$ for a week, polyphenol oxidase activity decreased sharply during the first four days at $20^{\circ}C$, then decreased slowly as the storage was prolonged. At $4^{\circ}C$, the polyphenol oxidase activity appeared to be relatively stable during the first two days before activity began to decline sharply. Polyacrylamide disc gel electrophoresis indicated four bands with polyphenol oxidase activity. Three bands and one band of the active bands were observed after heating for 1hr at $60^{\circ}C\;and\;70^{\circ}C$ respectively. The enzyme activity was observed 40% after treatment at $60^{\circ}C$ and 5% after treatment at $70^{\circ}C$. Therefore, no difference in the thermal stability was observed between active bands and the enzyme activity.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 1993.12a
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• pp.6-9
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• 1993

According to changes in population, economic conditions, life-stile and eating habits, the frui ts and vegetables market wi 11 be shi fted from processed (i. e. , canned) to fresh. Undressed fresh produce, consisting of washed, disinfected and peeled fruits and vegetables that either sliced or grated, are currently increased in demand by retail and institutional market which use them as salad components or in ready-to use foods, Main attributes of minimally processed fruits and vegetables are convenience and fresh-like quality. Minimally processed Products readily deteriorate in quality, especially color and texture, as a result of endogeneous enzyme enhanced respiration and microorganisms which lead to reduced shelf Iife. According to changes in population, economic conditions, life-stile and eating habits, the frui ts and vegetables market wi 11 be shi fted from processed (i. e. , canned) to fresh. Undressed fresh produce, consisting of washed, disinfected and peeled fruits and vegetables that either sliced or grated, are currently increased in demand by retail and institutional market which use them as salad components or in ready-to use foods, Main attributes of minimally processed fruits and vegetables are convenience and fresh-like quality. Minimally processed Products readily deteriorate in quality, especially color and texture, as a result of endogeneous enzyme enhanced respiration and microorganisms which lead to reduced shelf Iife. Thus. to prevent these undesirable changes , val'ious techniques such as controlled atmosphere (CA) storage, modified atmosphere OIA) storage, including vacuum packaging have been receiving considerable attention, Although milch research has been done to find optimal conditions for whole intact frui ts and vegetables, only limi ted information is avai lable on fresh cut. and other minimally processed products. 81 iced frui ts exhibi t increas~d ethylene production and respiration compal'ed to whole f, 'uits during distribution in response to tissue damage. As a result, accelerated senescence and enzymatic browning OCCUI', Recent l'esearch on minimally processed fl'uits and vegetables has mainly focused on methods to inhibit browning, due to ban on use of sulfur dioxide, In order to retard or prevent these physiological changes, val'ious al ternatives, reducing agents. acidulants, chelating agents and inol'ganic sal ts have been evaluated for use on fresh cut fl'ui ts. Al though some agents were effective replacement for sulfur dioxide. consum$\textregistered$I'S demandless use of chemical on such products. Shel~ life of minimally processed products has been extended by inhibition of metabolic reactions associated with loss of quality and by inhibition of aerobic spoilage caused by wide variety of microorganisms. Appl ication of ~I.-\ packaging, including vacuum packaging, retards the rate of respiration, prevents growth of aerobic spoilage organisms, inhibits oxidation and color deterioration. Tissue softening is another major problem in minimally processed products because enzymes re 1 a ted to ce 11 wa 11 degrada t i on are not inactivated. Various treatments have been investigated for retardation of the softening of sliced products. Some studies have concentrated on the application of an active packaging system with ~I, l. packaging and calcium infi 1 tration as possible measures to retain firmness of processed products. In my opinion, one important step for production of minimally processed frui ts wi th favorabl e color of cut surface and firm texture is the selection of better cultivar. As the view, changing tendency of fresh color by apple cultivars and relationship between the tendency and PPO activity will be discussed in the seminar. In addition to the topic, research result on quality enhancement of fresh apple slices by heat shock treatment will be introduced.