Optimization of Caproic Acid Production from &lt;em&gt;Clostridium kluyveri&lt;/em&gt; H588 and its Application in Chinese Luzhou-flavor Liquor Brewing

Shoubao Yan,Zhenfang Qiu,Guoguang Wei,Kegui Zhang,Shunchang Wang

doi:10.19026/ajfst.7.1368

Abstract

This study focused on the optimization of caproic acid production from Clostridium kluyveri H588 and its application in Luzhou-flavor liquor brewing. The critical variables that affected caproic acid production were identified by Plackette-Burman design (ethanol, sodium acetate, yeast extract and initial pH) and further optimized by using a four factor central composite design of response surface methodology. The results demonstrated that the optimum conditions for caproic acid production were determined to be ethanol concentration of 4.046% (v/v), sodium acetate concentration of 0.982% (w/v), yeast extract concentration of 0.145% (w/v) and initial pH of 6.41. Caproic acid production (214.23 mg/100 mL) in the optimized condition was in good agreement with the value predicted by the model equation (219.11 mg/100 mL), thereby assuring its effectiveness. Furthermore, the optimized condition of the lab-scale bioreactor was scaled-up to 5000 L fermentor and the obtained caproic acid broth was subjected to pit-filling fermentation. The result demonstrated this method of pit-filling fermentation was efficient in improving the quality of Luzhou-flavor liquor.

Highlights

Chinese liquor is a traditional alcoholic beverage, which is consumed widely in China and plays an important role in Chinese life and culture (Zhang et al, 2012)
In the traditional solid fermentation of Luzhouflavor liquor, pit mud is the basis of liquor flavor, as it habitated a large number of microbes such as caproic acid bacteria, lactic acid bacteria, butyric acid bacteria, acetic acid bacteria and methane bacteria etc., which were believed to play key roles in the formation of aroma substance, and gave Luzhou-flavor liquor special feature described as highly flavored, sweet and refreshing (Chen et al, 2010)
In Chinese brewing liquour industry, in order to improve the flavor of Luzhou-flavor liquor, it should be necessary to increase the production of ethyl caproate

Summary

Introduction

Chinese liquor is a traditional alcoholic beverage, which is consumed widely in China and plays an important role in Chinese life and culture (Zhang et al, 2012). It is typically classified into five categories based on aroma characteristics: Luzhouflavor style, light aroma style, soy sauce aroma style, sweet honey style, and miscellaneous style (Li et al, 2013, 2012). Caproic acid bacteria is one of the most important acid producing microbes, as it was intimately associated with the production of ethyl caproate and its precursor caproic acid. Its use in pit-filling fermentation was rarely investigated

Methods

Results

Conclusion