• 한국식품과학회지
• /
• 제30권5호
• /
• pp.1134-1139
• /
• 1998

막여과 약주의 저장 중 품질변화를 관찰하기 위하여 여러 가지 종류의 여과막으로 여과한 약주를 $25^{\circ}C$에서 50일간 저장하면서 약주의 pH, 적정산도, 탁도 및 총균수, 젖산균수, 효모수를 측정하였다. 비살균 약주는 저장 중 적정산도, 탁도, 생균수가 증가한 반면 pH는 감소하였다. 막여과 약주의 경우 적정산도와 탁도의 변화가 관찰되지 않았으며 약주내 미생물들이 관찰되지 않아 높은 저장성을 보여주었다. 키토산을 0.1% (w/v) 첨가하였을 경우에는 생균수의 급격한 감소현상을 나타내어 높은 살균력을 지니고 있음을 알 수 있었다.

• 치위생과학회지
• /
• 제19권1호
• /
• pp.1-8
• /
• 2019

Background: Erosion is a gradual process that occurs fairly quickly, and the full extent of the erosive effects of acidic beverages is not yet clear. The present study aimed to determine the differences in the erosive potentials among four naturally acidic fruit nectars within the same range of titratable acidity and to determine the influence of the components of organic acids on tooth erosion. Methods: Diluted fruit nectars (mandarin 1:1.1, orange 1:1.7, lemon 1:15, grapefruit 1:20) with the same range of titratable acidity (7.9 ml) and their corresponding organic acids (0.05%, 0.1%, 0.3%, and 0.5% citric acid, malic acid, and a citric and malic acid mixture [pH 2.8], respectively) were used. Specimens were placed in conical tubes with 50 ml of each of the test solutions for 1 hour. A microhardness test and scanning electron microscopy were used to measure enamel erosion. Acid separation was carried out using high-performance liquid chromatography to analyze the composition of each test solution. Results: Similar decreases in the Vickers hardness number (VHN) were observed among the groups treated with the following diluted fruit nectars: diluted mandarin nectar ($75.9{\Delta}VHN$), diluted lemon nectar ($89.1{\Delta}VHN$), diluted grapefruit nectar ($91.7{\Delta}VHN$), and diluted orange nectar ($92.5{\Delta}VHN$). No statistically significant differences were found in the enamel surface hardness after erosion (p>0.05). Citric and malic acids were the major organic acids in the test fruits. The lemon and orange groups had the highest malic acid concentrations, and the mandarin group had the lowest malic acid concentration. Conclusion: The titratable acidity and the citric and malic acid contents of the fruits could be crucial factors responsible for enamel erosion. Therefore, fruit-based drinks should be regarded as potentially erosive.

• Food Science and Biotechnology
• /
• 제15권6호
• /
• pp.902-907
• /
• 2006

Freeze dried crude bacteriocin was encapsulated within an acid-soluble coating material, Eudragit EPO, using a surface modification technique through a hybridization system. The pH and titratable acidity of control yoghurt were 3.92 and 1.56%, respectively, after 24 hr of fermentation at $42^{\circ}C$, whereas yoghurt containing 500 AU/mL encapsulated bacteriocin exhibited a higher pH (4.37) and lower titratable acidity (1.2%). Yoghurt containing encapsulated bacteriocin had significantly lower titratable acidity when the duration of fermentation (to pH 4.5) and subsequent refrigerated storage ($4^{\circ}C$) was longer than 20 days. There were no significant differences in the viability of lactic acid bacteria after 15 hr of fermentation. This suggests that microencapsulated bacteriocin has the potential to control the excessive growth of yoghurt starters caused by temperature abuse or post-acidification.

• 한국축산식품학회지
• /
• 제21권2호
• /
• pp.156-162
• /
• 2001

The quality changes of UHT market milk product were investigated by the season and storage conditions. Throughout the year, standard plate counts(SPC) wasnt increased significantly during storage at 5$\pm$1 and 7$\pm$1$^{\circ}C$ for 10 days. And except for summer, SPC was lower than 20,000 cfu/ml after storage at 10$\pm$1$^{\circ}C$ or 10 days. But SPC was rapidly increased from 3 days at 15$\pm$1$^{\circ}C$, and there was gas forming by yeast growth after storage at 30$\pm$1$^{\circ}C$. Values of pH and titratable acidity of market milk products were 6.49 to 6.71 and 0.155 to 0.16%, respectively. pH and titratable acidity were a lot changes at the temperature over 15$\pm$1$^{\circ}C$, and milk products showed a curd at 30$\pm$1$^{\circ}C$. Carbohydrate of market milk product had little difference throughout the year, whereas fat, protein and total solids of market milk products in autumn showed a little higher value than that of other seasons. There were no changes of milk composition during storage periods, but carbohydrate was decreased a little after storage over 20$\pm$1$^{\circ}C$.

• Food Science and Biotechnology
• /
• 제18권3호
• /
• pp.636-640
• /
• 2009

The effect of post-cut vanillin treatment at high concentrations on changes of quality and microorganism in fresh-cut apples was studied. Apples (Malus domestica Borkh. cv. Fuji) were sliced, treated by dipping in different vanillin solution, 0, 40, 80, and 120 mM, packed in polyethylene bag, and then stored for up to 3 weeks at $4^{\circ}C$. Changes in total aerobic bacteria, yeast and molds, browning, soluble solids, and titratable acidity during storage were investigated. Growth of total aerobic bacteria throughout storage was strongly inhibited by vanillin regardless of treatment concentrations. Growth of yeast and molds was inhibited by vanillin of all concentrations until 2 weeks of storage. Levels of browning index, soluble solids, and titratable acidity were not significant difference among the treatment conditions until 2 weeks of storage. However, when stored for 3 weeks, browning index increased more at 80 or 120 mM vanillin, while soluble solids and titratable acidity more be decreased by 120 mM vanillin as compared with other treatment conditions. These results show that the usage of vanillin in processing of fresh-cut apples had a limitation for maintaining quality.

• 한국식품조리과학회지
• /
• 제11권1호
• /
• pp.37-43
• /
• 1995

본 연구의 김치시료는 절인 배추를 수세하여 초산 0.01%, 0.05%, 0.1%의 수용액에서 10분간 침지 후 건져서 김치를 제조하였다. 김치발효중 배추를 중륵과 엽신별로 그 숙성도변화를 관찰하고, 초산첨가 농도에 따른 영향을 알아 보았다. 또한 김치숙성도 판정을 위한 여러방법(pH, 총산도, 휘발성산도, ascorbic acid함량, resazurin test value, pH/acidity ratio)간의 상관성을 검토하였다. 중륵과 엽신의 숙성도는 pH와 산도를 기준으로 관찰할 때 중륵이 엽신보다 숙성이 빠른 경향으로 나타났으며, 적숙기이후에는 별 차이가 없었다. 1$0^{\circ}C$에서 배추김치의 발효중 대조구와 초산전처리구의 특징에 따른 차이는 별로 나타나지 않았다. 초산전처리한 김치는 pH와 총산도를 기준으로 볼 때 대조구에 비하여 김치의 숙성을 앞당기는 경향이었으며, 0.01% 초산전처리구만이 김치의 가식기간을 연장하는 듯 하였다. 이러한 결과는 Ascorbic acid 함량이 비교적 높게 유지된 것으로도 확인할 수 있었다. 휘발성산도는 초산전처리농도가 높을수록 높게 나타났으며, ascorbic acid 함량은 엽신보다 중륵에서 높은 값을 보였고, 초산전처리농도가 높을수록 낮아지는 경향을 나타냈다. 본 실험의 적숙기인 발효 제 3~6일의 pH는 4.6~4.4, 총산도는 0.4~0.5%, ascorbic acid함량은 7.5~11.5 mg%, RV는 4.5~5.0 그리고 pH/acidity ratio는 9~10을 나타냈다. 1$0^{\circ}C$에서 발효시킨 김치의 중륵과 엽신의 RV, 휘발 성산도, ascorbic-acid함량 그리고 pH/acidity ratio는 pH, 총산도와 상관성이 매우 높은 것으로 나타났다.

• 한국식생활문화학회지
• /
• 제4권2호
• /
• pp.167-172
• /
• 1989

김치의 숙성과정 중의 물리적 특성을 측정하기 위하여 원료배추의 엽두께, 절임시의 두께 및 pH, total acidity, 염도 등의 변화를 연구하였다. 원료배추의 엽두께는 최외엽보다 내엽의 두께가 50% 감소되었고 절임의 경우에서는 외엽이 내엽보다 감소율이 낮았다. 배추조직의 절단력 측정에서는 절임으로 인하여 상대적인 절단력이 높았고 김치숙성이 되면서 증가하며 7일을 기준으로 감소하였다. Stress에서도 상대적 절단력과 같은 경향이나 숙성 후의 감소되는 점이 잘 나타나지 않았다. pH의 변화에 대한 상관식은 Y=0.23X+6.13이었고 젖산함량의 관계식은 Y=0.09X-0.01로서 매우 완만한 기울기이었으며 김치로서의 적정수준은 pH4.2, 젖산함량은 0.63의 수준이었고 기간은 7일이었다.

• 한국식품저장유통학회지
• /
• 제4권3호
• /
• pp.265-270
• /
• 1997

Effect of modified atmosphere packaging conditions on quality changes of dry jujube was investigated. Dry jujubes with moisture content of 26.7% were packaged in PET/Al/PE film pouches with modified atmospheres. The tested packages include those with normal air, vacuum, CO2 flushing, N2 flushing and O2 scavenger. Packages were stored at 25$^{\circ}C$ for 6 months, during which ascorbic acid concentration, browning level, titratable acidity and surface color were measured. Generally modified atmosphere packages could improve quality retention of dry jujubes except that vacuum package resulted in large surface color change. CO2-flushed package showed the best quality retention of high ascorbic acid content and low browning during 112 days, but caused high amounts of ascorbic acid destruction and browning in longer storage. In all the modified atmosphere packages titratable acidity reached a maximum followed by decline and subsequent rise, while it increased linearly with time in normal air package. Considering ascorbic acid retention browning level and surface color changes during 112 days, the packages of CO2 flushing and N2 flushing were better than others.

• 한국식품영양과학회지
• /
• 제27권3호
• /
• pp.495-500
• /
• 1998

To compare the extent of heat treatment in domestic infant formula, pH,titratable acidity, undenatured whey protein contents, HMF contents and protein-reducing substances of three commercial products (A, B, C) were measured. The pH of B products was lowest and the titratable acidity of B product was highest. The contents of undenatured whey protein per 100ml serum were 0∼30mg(A products), 90∼130mg(B products)and 80∼90mg(C products), respectively. Distinct differences of undenatured whey protein contents according to the manufacturer and infat's stage in age could be observed. The HMF contents of tested products showed 10.9∼21.5umol/L and B-2 product(B products for the second stage of 5∼9 month) was the highest among tested products. The protein-reducing substances showed 4.46∼9.50mg K4Fe(CN)6/100ml serum nd B-2 product was the highest among tested products.

• 동아시아식생활학회지
• /
• 제16권3호
• /
• pp.349-356
• /
• 2006

This study was carried out to survey the effect of Jujube extract on the growth of 3 strains of lactic acid bacteria(LBA) starter cultures in the MRS broth by the addition of 0, 0.1, 0.5, 1 and 2% extract The pH, titratable acidity and OD of LAB were investigated in order to get fundamental knowledge for the development a new product. The effects of Jujube extract on the growth of LAB were variable depending upon the LAB species and concentrations of Jujube extract significantly (p<0.05). In the results, Jujube extract enhanced the acid production and propagation by the 3 LAB strains with increasing concentration of Jujube extracts until 2.0% added was to the MRS broth medium (p<0.05). Addition of Jujube extract markedly stimulated the acid production and propagation of Lactobacillus acidophilus, Streptococcus thermophilus and Bifidobacterium longum.