Effect of high hydrostatic pressure (HHP) treatment on chemical and microbiological properties of Makgeolli

Abstract

Chemical and microbiological properties of Makgeolli after high hydrostatic pressure (HHP) treatment were investigated to determine the possibility of shelf-life extension. Laboratory prepared Makgeolli was treated with 400MPa for 5 min and stored for 6 days at 25°C and chemical and microbial properties were analyzed. On day 6 the alcohol content of untreated Makgeolli was 8.27%, whereas HHP-treated showed 7.50%, and pH were 2.76 and 3.22, respectively. Titratable acidity of HHPtreated Makgeolli was increased by less than 0.1%, whereas the untreated was increased by more than 0.3% on day 6. Reducing sugar content, on the other hand, increased continuously in HHP-treated Makgeolli, and reached to 2.43% by day 6, but decreased to 1.13% in untreated Makgeolli. In HHP-treated Makgeolli, yeast was reduced to below detection limit and grew again on day 6. Lactic acid bacteria were also reduced by HHP, but reappeared within 2 days at the level of 1-2 logs CFU/mL. HHP slowed down the chemical changes such as pH, titratable acidity, and alcohol content; thus showing HHP treatment can be used to extend the shelf-life of Makgeolli by inactivating lactic acid bacteria and yeast. © 2013 The Korean Society for Applied Biological Chemistry.