Study on fermentation conditions of palm juice vinegar by response surface methodology and development of a kinetic model

Abstract

-Natural vinegar is one of the fermented products which has some potentiality with respect to a nutraceutical standpoint. The present study is an optimization of the fermentation conditions for palm juice vinegar production from palm juice (Borassus flabellifer) wine, this biochemical process being aided by Acetobacter aceti (NCIM 2251). The physical parameters of the fermentation conditions such as temperature, pH, and time were investigated by Response Surface Methodology (RSM) with 2 3 factorial central composite designs (CCD). The optimum pH, temperature and time were 5.5, 30 °C and 72 hrs for the highest yield of acetic acid (68.12 g / L). The quadratic model equation had a R 2 value of 0.992. RSM played an important role in elucidating the basic mechanisms in a complex situation, thus providing better process control by maximizing acetic acid production with the respective physical parameters. At the optimized conditions of temperature, pH and time and with the help of mathematical kinetic equations, the Monod specific growth rate ( μ max = 0.021 h -1 ), maximum Logistic specific growth rate ( μ ' max = 0.027 h -1 ) and various other kinetic parameters were calculated, which helped in validation of the experimental data. Therefore, the established kinetic models may be applied for the production of natural vinegar by fermentation of low cost palm juice.

Microbial diversity and their roles in the vinegar fermentation process

“…Furthermore, the more stringent the growth conditions are, the greater the selective pressure exerted on the indigenous microorganisms ). Natural vinegar made from different sources of derived ethanol (such as cider, beer, wine, and fermented fruit juice) by spontaneous fermentation methods not only contains small amounts of citric acid, tartaric acid, and other organic acids, but also require a long fermentation time (Ghosh et al 2012). To increase the speed of the biological reaction, the dominant AAB are used in the aerobic transformation of ethanol into acetic acid, and various fermentation methods have been developed (De Ory et al 2004;Tesfaye et al 2002b).…”

“…In AAF, the important physicochemical parameters that affect the growth of microorganisms are pH and acidity (Ghosh et al 2012). At lower pH of vinegar, the growth of most microorganisms is believed to be inhibited.…”

Enhanced acetic acid production from manalagi apple (Malus sylvestrismill) by mixed cultures ofSaccharomyces cerevisiaeandAcetobacter acetiin submerged fermentation

“…Microorganisms commonly used in the fermentation of alcohol were Saccharomyces cerevisiae and Zymonas mobilis [1,2]. Karsch et al [2] stated that for industrial fermentation Z. mobilis seemed to be inferior to S. cerevisiae due to the lower biomass production of the bacterium by the decrease in pH.…”

“…Ghosh et al [1] performed acetic acid production in two separated steps by adding sterile sugar and A. aceti starter culture after two days of ethanol fermentation by using S. cerevisiae, while Singh and Singh [4] adding inoculum A. rancens after 24 hrs. According to the characters of growth and metabolization of S. cerevisiae and A. pasteurianus, Wang et al [5] conducted acetic acid process in three stages: the first stage for growth of S. cerevisiae, the second stage for co-culture of S. cerevisiae and A. pasteurianus, and the third stage for growth of A. pasteurianus.…”

“…According to the characters of growth and metabolization of S. cerevisiae and A. pasteurianus, Wang et al [5] conducted acetic acid process in three stages: the first stage for growth of S. cerevisiae, the second stage for co-culture of S. cerevisiae and A. pasteurianus, and the third stage for growth of A. pasteurianus. Generally, fermentation temperature and aeration rate were controlled differently at every stage [1] [3]. Because it involved several different processes, the operational procedures of acetic acid fermentation became complicated and required a longer time.…”