The purpose of this study is to compare the quality characteristics and antioxidant activities of the tagatose yogurt with different contents (6, 8, 10%) of cold brew liquid coffee. Tagatose is a low-calorie food ingredient with putative health-promoting benefits. The tagatose yogurt was fermented with Lactobacillus delbrueckii subsp. bulgaricus at 37±1oC for 20 h. The changes in acid production (pH and titratable acidity), viscosity, and lactic acid bacteria were determined every 5 h during fermentation. Color value was determined before and after fermentation, and antioxidant activities were performed after fermentation in triplicate. The yogurts containing cold brew liquid coffee had lower pH, higher acidity, and viscosity than the control, regardless of the liquid coffee contents. All samples had increasing levels of lactic acid bacteria over the fermentation period, but lactic acid bacteria of yogurts with the addition of cold brew liquid coffee increased further than the control. The total polyphenol/flavonoid content, DPPH/ ABTS/H2O2 radical scavenging activities, and reducing power increased when the liquid coffee content of the yogurt rose. Consequently, the optimal quality of tagatose yogurt was found when 6-8% of cold brew liquid coffee was added according to the overall results of quality properties and antioxidant activity.

최근 원액상태로 장시간 보관이 용이하고 특유의 향을 유지할 수 있는 콜드브루커피가 남녀노소에게 크게 인기를 얻음에 따라 커피판매업체의 규모와 수가 증가하고 있으며, 명절 선물용으로도 각광을 받고 있다. 콜드브루커피는 차가운 물로 장시간 추출한 커피이므로 세균에 노출될 가능성이 크다. 따라서 본 연구는 시중판매되고 있는 콜드브루커피의 안전성을 조사하여 소비자에게 올바른 정보와 건강한 먹거리를 제공하고자 하였다. 총 75건 의 콜드브루커피를 대상으로 식품공전 액상커피의 규격 기준(세균수, 대장균군)과 식중독균 9종 및 카페인 함량 검사를 실시하였다. 조사한 결과 온라인에서 구매한 9개 제품의 세균수가 규격기준을 크게 초과하여 검출되었으며, 대장균군 및 식중독균 9종은 검출되지 않았다. 또한 조사한 콜드브루 제품의 평균 카페인 함량은 1.6 mg/mL (240 mL 제품의 경우 카페인 384 mg 함유)이며, 카페인 과다 섭취 시 불면증, 신경과민 등 부정적인 작용들이 존재하므로 성인 기준으로 카페인 최대 일일섭취권고량 400 mg/day을 초과하지 않도록 주의가 필요한 것으로 나타났다.

This study was carried out to investigate the changes of the microbiological contamination levels, pH, acidity, solid contents, total phenol contents, and color difference of cold-brew coffee products during 4 weeks at room and cold temperatures. The 17 sample coffees were purchased from regional cafes in Jeonju. Each coffee was self-blended by the cafes. Esherichia coli was not detected in all the samples, but bacteria were detected in 1 sample and yeast and molds were detected in 4 samples. Of the samples stored at room temperature (25oC) after 4 weeks, general bacteria were detected in 4 samples (3.0×101 cfu/ml-1.7×103 cfu/ml), and yeast and molds were detected in 11 samples (1.3×101 cfu/ml - 3.1×105 cfu/ml). In the case of the samples stored at cold temperature (4oC), general bacteria were detected in 3 samples, and yeast and molds were detected in 6 samples although the level of contamination was lower than that at room temperature. pH and acidity decreased during the storage period, but the total phenol content did not change. In the case of chromaticity, redness and yellowness tended to decrease.

Coffee is a commonly consumed beverage that contains anti-inflammatory compounds such as caffeine, chlorogenic acid, cafestol, trigonelline, and kahweol. Lactobacillus plantarum is a lactic acid bacterium most frequently used in the fermentation of food products of plant origin. L. plantarum is able to degrade some food phenolic compounds and provide high value-added compounds such as powerful antioxidants or food additives approved as flavouring agents. In this study, we investigated the anti-inflammatory effects of coffee extract fermented by L. plantarum on RAW264.7 macrophages. In lipopolysaccharide-stimulated RAW264.7 cells, these coffee extracts exhibited antiinflammatory activities through the reduction of nitric oxide (NO) production and inducible NO synthase expression. Fermented coffee extracts significantly decreased the expression of inflammatory cytokines such as tumor necrosis factor α, interleukin 1β, interleukin 6, and interferon γ. Cyclooxygenase-2, which is one of the key biomarkers for inflammation, was significantly suppressed. These results might be helpful for understanding the anti-inflammatory mechanism of fermented coffee extract on immune cells and, moreover, suggest that fermented coffee extract may be a beneficial anti-inflammatory agent.