γ-アミノ酪酸(GABA)を増強したサトウキビ乳酸発酵飲料の開発  [in Japanese] Development of GABA-enhanced Lactic Acid Beverage Using Sugar Cane and its Functionality  [in Japanese]

サトウキビ搾汁液を乳酸発酵させてGABA増強など栄養生理機能付与による，高い機能性を有した乳酸発酵飲料の開発を行い，以下の結果を得た．（1）サトウキビ搾汁液を含むサトウキビ乳培地を用いて，GABA生産量と官能評価を指標にスクリーニングした結果，Lactococcus lactis NH-61株を選抜した．培地中のサトウキビ搾汁液濃度を高めると乳酸発酵飲料中のGABA含有量は増加し，脱脂乳の濃度を下げるとGABA含有量が低下することから，培地組成はサトウキビ搾汁液30％，脱脂乳10％が適当であった．乳酸菌スターターの添加量はGABA含有量に大きく影響しなかった．発酵温度は30℃以上が適しており，20℃以下ではGABA含有量が増加しなかった．培養時間は48〜72時間が適していた．サトウキビの品種や収穫時期によってGABA含有量は異なるが，サトウキビ乳酸発酵飲料中のGABA含有量には大きな差異は生じなかった．（2）サトウキビ乳酸発酵飲料はカリウムやマグネシウム等のミネラルを多く含み，ポリフェノール含有量や抗酸化性も増加した．また，抗変異原性も高い値を示した．

Sugar cane-fermented lactic acid beverage including functional nutritional components, such as γ-aminobutyric acid (GABA), was developed from the perspective of the development of sugar cane as a resource for fermented lactic acid beverages. Based on a screening of lactic acid bacteria, Lactococcus lactis was selected for GABA productivity to an index in skim milk medium containing sugar cane juice. The optimum conditions for GABA productivity were as follows : sugar cane juice content, 30% ; skim milk content, 10% ; fermentation temperature, higher than 30°C ; and fermentation time, 48 to 72hrs. The quantity of the starter culture of Lc. lactis did not influence GABA content in lactic fermentation beverage. GABA increased with increased sugar cane juice content, and decreased with lowered skim milk content. GABA productivity was not shown for fermentation at temperatures less than 20°C. The GABA content of the sugar cane differed with breed or crop season. However, these differences did not influence GABA content of the lactic fermentation beverage. Sugar cane fermented lactic acid beverage included a high level of minerals, such as potassium and magnesium, and polyphenolics. DPPH-radical scavenging activity increased in reflection of the high content of polyphenolics. In addition, antimutagenic activity of lactic fermentation beverage was increased by using sugar cane.