유청음료(乳淸飮料)의 개발에 관한 연구 = Studies on the Development of Whey Drinks

국문 초록 (Abstract)

본문은 유청을 이용한 음료개발 분야의 기초연구로써 유청에 유산균을 발효시켜 만든 유산균 발효유청과 비발효 유청을 대상으로 인삼과 당을 첨가하여 관능검사를 통한 음료의 타당성과 이후 발효 유청음료 개발의 기초자료를 제공하기 위하며 발효기간별 pH 산도, 일반성분 및 유기만의 변화를 비교 검토하여 다음과 같은 결과를 얻었다.
1. 유청의 pH는 6.14, 산도는 0.11%이었으며 순단백질은 0.77g%, 유당 4.89g%, 회분은 0.46g%를 나타내었으나 음료의 조제 후에는 pH 5.63, 산도 0.26%이었고 기타 일반성분 및 유기만의 함량은 유사하였다.
2. 발효 유청음료의 pH는 발효 1일에 급격히 낮아졌고 산도는 매우 빠르게 증가하였으나 이후 4일까지의 변화는 완만하였다.
3. 순단백질함량은 발효 1일에 약 13% 감소하였으며 이후 4일까지의 변화는 완만하였다.
4. 유당함량은 발효 1일에 약 14% 감소하였으며 이후 4일까지 완만하게 감소하였다.
5. 비발효 유청음료중의 젖산함량은 8㎎%이었는데 발효 1일에 200㎎%로 급격히 증가하였으며 이후 4일까지 완만히 증가하였다.
6. 유청에서 검출되지 않은 succinic acid가 발효 유청음료에서 생성되어 발효기간에 따라 점차 증가하였다.
7. 관능검사 결과는 비발효 유청음료의 경우가 오히려 더 좋은 점수를 얻었는데 이는 발효과정중 succinic acid 이외 off-flavor 성분이 새로이 생성되는 이유로 생각된다.

다국어 초록 (Multilingual Abstract)

This paper is a fundamental study on the whey drink preparation.
Sensory evaluation was taken initially after adding ginseng extract and sucrose both to lactic acid bacteria fermented and nonfermented whey in order to observe the validity of the drinks.
The changes of pH, acidity, proximate components and organic acid according to the period of fermentation were examined and compared each other in order to offer the basic data on fermented whey drink preparation.
The results obtained were summerized as follows:
1. The pH of whey was 6.14, its acidity 0.11%, its pure protein content 0.77g%, its lactose content 4.89g%, its ash content 0.46g% before processing, but the pH and acidity of whey were changed respectively, into 5.63 and 0.26% after processing, and other proximate components and organic acid were not changed.
2. The pH of the fermented whey drink was diminished extremely and also its acidity changed very fast during 1st day in fermentation, but the changes were very slow till 4th day.
3. The amount of pure protein was diminished about 13% at 1st day in fermentation and, afterward, was changed very slow till 4th day. But the changes in amount of nonprotein nitrogen was opposite.
4. Lactose content was diminished about 14% at 1st day in fermentation and, afterward, was changed very slow till 4th day.
5. The amount of lactic acid, which was 8㎎% in nonfermented whey drink, was increased very fast at 1st day in fermentation and, afterward, was increased very slow till 4th day.
6. Succinic acid, not found in whey, was produced in fermented whey drink and increased more and more according to the period of fermentation.
7. Nonfermented whey drink gained better score than fermented whey drink in sensory evaluation. It should be because of succinic acid and other off-flavor components which was produced newly during the proces of fermentation.