논문 상세보기
pp.71-77
요구르트 제조시 고형분 함량을 증가시키기 위해 첨가하는 탈지분유의 일부를 자색고구마로 대체(고형물비로 22.7, 38.6, 63.6%)하여 요구르트를 만들고, 탈지분유만 첨가한 대조구와 비교하여 젖산균의 생육과 산생성, 점도, 관능성, 유기산 및 색도를 조사하였다. 자색고구마의 첨가로 젖산균의 산생성은 감소되어 발효 24시간 후 자색고구마 첨가 요구르트가 1.114∼1.228%로 탈지분유만 첨가한 대조구의 1.268%보다 상당히 낮은 것으로 나타났다. 젖산균의 생육은 자색고구마의 첨가로 감소되어 24시간 발효 후 9.08∼9.33 log cfu/ml였으나 탈지분유만 첨가한 대조구는 9.62 log cfu/ml로 가장 높았다. 자색고구마 첨가 요구르트의 점도는 고형물비로 63.6% 첨가한 구에서 46, 000 cps로 대조구의 32, 200 cps보다 상당히 높은 것으로 나타났다. 전체적인 기호도는 자색고구마 첨가구가 대조구에 비해 우수하였으며, 그 중 고형물비가 38.6% 첨가된 요구르트가 가장 높았으나, 조직감에서는 오히려 대조구가 더 우수하였다. 유기산 중 젖산 함량은 자색고구마 첨가로 감소되었으며, oxalic acid, fumaric acid, succinic acid 그리고 mailc acid도 소량 검출되었다.
New type yogurt base were prepared from milk added with skim milk powder or purple sweet potato, and fermented by lactic acid bacteria(Streptococcus thermophilus and Bifidobacterium infantis, 1:1, v/v). The yogurt products were evaluated for acid production(pH, titratable acidity), number of viable cell, viscosity, sensory propertices, and color value. The composition of some organic acids was also analyzed by GC. The acid production slightly decreased by addition with purple sweet potato. There was no significant difference in viable cell counts between control(yogurt added with only skim milk powder) and yogurt added with purple sweet potato, and viable cell counts of all samples were above 9.08 log cfu/ml. Viscosity of yogurt added with purple sweet potato(36, 800∼46, 000 centipoise) was higher than that of yogurt added with only skim milk powder(32, 200 centipoise). The overall sensory score of yogurt added with purple sweet potato(38.6%, dry base) was the best of tested yogurt. The major organic acid of yogurt added with purple sweet potato was lactic acid, its content was 0.997∼1.203%, malic acid, succinic acid, oxalic acid, and fumaric acid were analyzed out a little. Lightness and yellowness decreased by addition with purple sweet potato but redness increased. Total color difference(△E) with yogurt addition with purple sweet potato and only skim milk powder were very high(above 11.46).
