• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.375-379
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• 1999

This study was designed to develop non-thermal pasteurized fresh apple juice by applying pulsed electric field (PEF) treatment. The effect of non-thermal PEF treatment on physicochemical and sensory properties of apple juice was examined by measuring changes in vitamin C contents, colors, flavors and sensory properties. Color of PEF and heat treated apple juices was not significantly different from each other. Vitamin C content of PEF treated apple juice was close to that of fresh apple juice, but was much higher than that of heat treated apple juice. Heat treated apple juice lost 70% of flavor components, whereas PEF-treated apple juice lost only 15%. Sensory scores of PEF treated apple juice were significantly higher than heat-treated one in flavor, taste and overall acceptability. In conclusion, PEF treated apple juice had superior physico-chemical and sensory properties to heat-treated one.

• Food Science and Preservation
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• v.19 no.2
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• pp.178-184
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• 2012

The physiochemical property, nutrient composition, and functionality of apple juice sterilized at a low temperature (LT, $70^{\circ}C$, 30 min) or a high temperature (HT, $100^{\circ}C$, 20 min) were analyzed. The pH of the apple juice that was sterilized at LT (pH 4.72) was higher than that of the apple juice that was sterilized at HT (pH 4.57), and the acidity of the apple juice that was sterilized at HT (8.90%) was higher than that of the other sample. The sugar content of the two apple juice samples was 15 $^{\circ}Brix$, and the apple juice samples had high potassium, malic acid, and glutamic acid contents. The total polyphenol contents of the apple juice samples that were sterilized at LT and HT were 27.39 mg/100 mL and 23.24 mg/100 mL, respectively. The apple juice that was sterilized at LT had a significantly stronger DPPH radical scavenging activity than the apple juice that was sterilized at HT ($p$ <0.01), and the apple juice that was sterilized at LT had a lower hydroxyl radical scavenging activity level than the other apple juice. Finally, the apple juice that was sterilized at LT showed significantly stronger activities that inhibit enzyme-related oxidation than the apple juice that was sterilized at HT ($p$ <0.05).

• Food Science and Preservation
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• v.21 no.2
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• pp.199-205
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• 2014

This study was conducted to investigate the physicochemical properties and antioxidant activity of black Doragi-apple juice to increase the utilization of Doragi, which is known as a high-functional horticultural crop. To prepare the black Doragi, it was steamed for 15 days at $60^{\circ}C$ and was then dried at $30^{\circ}C$ for 3 h. The five types of black Doragi-apple juice were prepared based on different mixing ratios of black Doraji extract, apple extract, and jujube extract. The mixing ratios of black Doraji extract, apple extract, and jujube extract were 3:3:1, 4:2:1, 2:4:1, 2:2:1, and 2:6:1 for samples A, B, C, D, and E, respectively. The pH and acidity of black Doragi-apple juice were within the ranges of 3.9-4.15 and 1.26-1.51%, respectively. Black Doraji-apple juice E showed the highest sugar content (9.33 $^{\circ}Brix$), reducing sugar content (85.05 mg/mL), and sugar content/acid ratio (6.98). Based on the sensory evaluation, sample C was most preferable in terms of color, taste, sugar-acid ratio, and overall preference, except for the flavor. Black Doragi-apple juice D showed a higher total polyphenol content (706 ${\mu}g/mL$) than sample C (586.22 ${\mu}g/mL$), but there was no statistically significant difference between samples C and D in terms of antioxidant activities. Therefore, it is suggested that the best mixing ratio of black Doraji extract, apple extract, and jujube extract for the production of the best black Doragi-apple juice with excellent taste and antioxidant activities is 2:4:1 (sample C).

• Food Science and Preservation
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• v.19 no.5
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• pp.712-719
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• 2012

In this study, the physicochemical and physiological activities of 10 different commercially available juices (apple juice-A: cloud type; apple juice-B: clear type; blueberry juice; grape juice-A; grape juice-B; orange juice-A; orange juice-B; pineapple juice; pomegranate juice; and tomato juice) were investigated. The average pH, titratable acidity, Brix, and reducing sugar were 3.57, 0.57%, $13.1^{\circ}Brix$, and 57.58%, respectively. The total polyphenol and flavonoid contents were within the ranges of 98.29-878.12 ug/mL and 23.82-156.63 ug/mL, respectively, and pomegranate juice showed the highest content, followed by blueberry juice and apple juice-A. In the DPPH radical scavenging assay, apple juice-A, grape juice-A, and pomegranate juice exhibited the highest activity (greater than 90%) while orange juice-B, pineapple juice and tomato juice showed the weakest. The tyrosinase inhibitory effect was highest in apple juice-A, followed by orange juice-A and blueberry juice. The reducing power was highest in pomegranate juice and lowest in pineapple juice and grape juice-A. The antioxidant activity by reducing power was highly correlated with the total polyphenol content.

• Food Science and Preservation
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• v.18 no.5
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• pp.700-705
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• 2011

The physicochemical qualities, antioxidant activities, and polyphenols composition of eight kinds of cloud and clear apple juice products marketed in Korea were investigated. The acidities of eight kinds of cloud and clear apple juice products were in the range of 0.299~0.556 and showed no significant difference (p<0.05). The soluble solid contents of the cloud type were higher than those of the clear type which had higher reducing sugar contents. The color value and turbidity of the cloud type were also higher, but the vitamin c contents showed no significant differences. The total phenolic contents of the cloud type (1.13~1.42 g/L) were four fold to eight fold higher than the clear type (0.12~0.32 g/L). Nine polyphenolic compounds, including chlorogenic acid, caffeic acid (-)-epicatechin, quercitrin, phloridzin, and 5-hydroxymethyl furfural (5-HMF), were isolated by HPLC analysis, and the total amount of the cloud type (319.37~985.63 mg/L) was higher than that of the clear type (92.88~214.39 mg/L). The antioxidant activities, by DPPH and FRAP assays, of the cloud type showed stronger than those of the clear type. The antioxidant activity and the color value were highly correlated with total phenolic content and polyphenols content (r>0.95).

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.1083-1093
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• 2007

The purpose of this study was to investigate the difference between students' beverage preference and dietitians' perception in elementary school lunch program. This study was conducted in three phases: (1) questionnaire development and survey administration to elementary school students (2) survey administration to dietitians who were in charge of the elementary school food service, and (3) comparison of beverage preferences between elementary school students and dietitians. In phase I, 703 elementary school students in Seoul were surveyed from July 11 to July 19. In Phase II, 100 school food service dietitians in Seoul participated by mail survey from September 15 to October 30, 2006. Based on the results, elementary school students tended to show a neutral milk preference (mean=3.04), whereas dietitians perceived that elementary school students had lower milk preference (mean=2.67). Also dietitians perceived higher yogurt preference (mean=4.27) than the real elementary school students' preference (mean=4.02). T-test results showed the gender difference on milk and yogurt preference. Male students had higher milk preference (t=4.912, p<0.001) and yogurt preference (t=3.621, p<0.001) than female students. Elementary school students showed high fruit juice preference (mean=4.34); however, dietitians perceived lower fruit juice preference of students (mean=3.92). There was no gender difference on fruit juice preference. Though elementary school students had higher fruit juice preference, the frequency of fruit juice served in school lunch was quite low. Over half of the dietitians reported that they served fruit juice less than once a semester. The results of this study indicated the existence of distinctive difference between students' fruit juice preference and school lunch menu offerings.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1484-1487
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• 1998

Superoxide dismutase (SOD)-like activities of sixteen kinds of fruits, vegetable juice and commercial concentrates were measured by pyrogallol autoxidation method. The changes in SOD-like activity by heat treatment and the increase in SOD-like activity of apple juice mixed with fruits and vegetables were investigated. SOD-like activity of broccoli juice was 41.7%, the highest value among tested sample. SOD-like activities of strawberry juice, carrot concentrate, kiwi juice, radish juice and apple juice were 30.2, 30.0, 27.6, 26.7, 24.1 and 14.6%, respectively. SOD-like activity was increased generally after heat treatment at $95^{\circ}C$ until 20 min. SOD-like activity of apple juice was increased $20{\sim}35%$ by mixing with 20% of carrot concentrate, kiwi juice, strawberry juice, broccoli juice, respectively and particularly was increased 48% by mixing with 20% of raddish juice.

• Applied Biological Chemistry
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• v.41 no.6
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• pp.431-436
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• 1998

The optimum ohmic heating condition of apple juice was investigated with model solution. The temperature rise of model solution was found to be $7.8,\;21.0,\;47.4^{\circ}C/min$ when the distances between electrodes were 29, 22, and 17mm, respectively. The heating rate increased proportionally with the numbers of electrode pairs, 1 to 3 and highly dependent on applied voltage. The heating rate was not affected by the frequencies ranged from 60 Hz to 60 KHz and the wave form of applied alternating electric current. The apple juices prepared by ohmic heating sterilization revealed similar physicochemical properties to that by commercial sterilization.

• Food Science and Preservation
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• v.17 no.1
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• pp.84-90
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• 2010

We investigated methods to minimize patulin content during processing of apple juice in Korea. Ascorbic acid concentration (100, 200, 300, and 400 ppm) and activated carbon concentration (50, 100, 150, and 200 ppm) were the parameters assessed by response surface methodology. Residual patulin was lowest in the presence of 237.77 ppm ascorbic acid and 106.58 ppm activated carbon, and increased as these levels increased. Sugar content was affected more byascorbic acid concentration than by activated carbon level, and the total phenol content was revealed to be the saddle point. In addition, the expected total flavonoid content was maximized with increased levels of ascorbic acid and activated carbon. The data showed that 246-274 ppm (v/v) ascorbic acid and 93-122 ppm (v/v) activated carbon were optimal for juice extraction, and the $R^2$ quality factor for juice processing was significant and within the range of 1-10% for all tested parameters.

• Food Science and Preservation
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• v.13 no.2
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• pp.138-143
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• 2006

Clarified apple juice was prepared using different clarification methods including centrifugation, ultrafiltration (UF), and combined treatment (CT). Effects of clarification methods as well as other qualify parameters were investigated Clarification was clearly improved with an increase in centrifugation speed and towering temperature. Especially, lowering the temperature led to a decrease in turbidity values at 5,000 rpm. The optimum condition for centrifugation process was $5^{\circ}C$ and 10,000 rpm, respectively. UF and CT were very effective to produce clarified apple juice. The optimum condition of UF process was $45^{\circ}C$ and 150 kPa considering flux and turbidity. L*-values were increased while a*-values were decreased significantly after clarification regardless of methods (P<0.05). Vitamin C was most retained in the clarified samples using CT.