A Study on The Preparation of Yogurt Added with Jujube Extract

대추 Extract를 첨가(添加)한 요구르트의 제조(製造)에 관한 연구(硏究)

Yogurts were prepared with skim milk powder added with jujube extract of 0%, 1%, 2%, 3%, 4%, 5%, respectively and fermented by mixed culture(Str. thermophilus, and Lac. bulgaricus). The fermented yogurts were evaluated for acid production(pH, titratable acidity), number of viable cell, change of sugars, sensory properties. 1. Addition of jujube extract increased acid production and decreased pH. Acid production was increased in proportion to concentration of jujube extracts added to milk and pH was decreased. 2. In yogurt fermentation, the lactic acid bacteria of yogurt added with jujube extract, increased in proportion to jujube extract concentration added to milk. 3. The viscosity was increased in proportion to concentration of jujube extract during 6 hrs. of fermentation. The viscosity of yogurt added with 4% and 5% jujube extract remarkably decreased for the first 12 hrs. Yogurt added with 5% jujube extract is lowest in its viscosity among the treatments. 4. The concentrations of glucose and fructose were higher in proportion of jujube extract add at 0 hrs. the concentration of lactose was decreased simultaneously, and those of galactose was increased in all the samples at 12 hrs. 5. The taste and odor of yogurt added with the jujube extract of 4% and 5%, respectively, were better than other samples. The color of control was better than other samples. The texture of control yogurt was better than orther samples, but was not clearly difference with the yogurts added with jujube extract of 4% and 5%. In the overall acceptability, the sensory scores of yogurt added with jujube extract of 3% and 4% were higher than other samples.

환원(還元) 탈지분유(脫脂粉乳)에 대추 extract를 0%, 1%, 2%, 3%, 4%, 및 5%를 첨가(添加)하고 혼합(混合) 유산균(乳酸菌)(Str. hermophilus, Lac. bulgaricus)으로 발효(醱酵)하여 요구르트를 제조한 후(後) 대추 extract 첨가가 유산균(乳酸菌)의 pH 및 산생성, 유산균(乳酸菌) 생육(生育)에 미치는 영향(影響), 점도변화(粘度變化), 당류변화(糖類變化) 및 관능검사(官能檢査)등을 조사한 결과는 다음과 같다. 1. 대추 extract 첨가군(添加群)이 대조군(對照群)에 비하여 산(酸) 생성(生成)의 증가(增加) 및 pH의 저하(低下)가 빨랐으며, 첨가구간에서도 대추 extract 첨가(添加) 농도(濃度)가 높을수록 pH의 저하(低下) 및 산(酸) 생성(生成)의 증가(增加)가 빨랐다. 2. 대조구(對照區)에 비하여 대추 extract 첨가구들의 유산균수(乳酸菌數)가 증가(增加)되었고, 첨가구들간에서도 첨가농도(添加農度)가 높을수록 유산균수(乳酸菌數)는 증가(增加)되었다. 3. 배양(培養) 6시간에는 대조구(對照區)에 비하여 대추 extract 첨가(添加) 농도(濃度)가 높을수록 점도(粘度)는 증가(增加)되었고, 4%, 5% 첨가구(添加區)는 12시간까지 급격한 점도(粘度) 저하(低下)가 나타났으나, 이중 5% 첨가구가 가장 낮았다. 4. 배양후 0시간에서는 대추 extract 첨가(添加) 농도(濃度)가 높을수록 glucose와 fluctose는 대조구(對照區)에 비하여 함량이 높아졌으며, 12시에서는 lactose는 대조구(對照區) 및 첨가구(添加區)들에서 비슷하게 감소(減少)되었고, fructose와 glucose도 감소(減少) 경향을 보였으며, galactose는 대조구(對照區) 및 첨가구(添加區)에서 0시간에 비하여 축적되는 경향을 보였다. 5. 관능검사 결과 맛(taste)과 냄새(odor)는 조구(照區)에 비하여 4%, 및 5% 첨가구가 우수하였으며, 색(色)(color)은 대조구(對照區) 대추 extract 첨가구(添加區)와 비교하여 우수하였고, 조직(Texture)은 대조구(對照區)가 대추 extract 첨가구들보다 좋았으나 4%, 및 5% 첨가구와는 유의적인 차이가 없었다. 전체(Overall)적으로는 대추 extract 3%,및 4% 첨가구가 우수하여 대추 extract 첨가(添加) 요구르트의 제조 가능성을 보여주었다.