Chemical, Microbiological, and Functional Characterization of Kefir Produced from Cow's Milk and Soy Milk.

Raúl Ricardo Gamba,Toshihide Michihata,Tetsuya Sasaki,Mahmoud Abdel-Hamid,Shihori Yamamoto,Takashi Koyanagi,Toshiki Enomoto

doi:10.1155/2020/7019286

Abstract

Kefir is a functional beverage that contains lactic and acetic acid bacteria (LAB, AAB) and yeasts. This work's aim was to study the chemical, microbial, and functional characteristics of kefir produced from cow's milk and soy milk. After fermentation, free amino acids were 20.92 mg 100 mL−1 and 36.20 mg 100 mL−1 for cow's milk and soy milk kefir, respectively. Glutamic acid was majority in both, suggesting that microbial proteolysis leads to an increase in free amino acids including glutamic acid. 108–109 CFU mL−1 LAB, 106–107 CFU mL−1 AAB, and 106–107 CFU mL−1 yeasts were counted in cow's milk kefir, whereas soy milk kefir contained greatly lower yeasts and AAB. Lactococcus lactis, Kazachstania unispora, and Saccharomyces cerevisiae were isolated as major microorganisms in both kefirs. Acetobacter orientalis only existed in cow's milk kefir. Cow's milk and soy milk showed ACE inhibitory activity, which significantly increased after fermentation. Both kefirs also exhibited antioxidant activity and bactericidal activity against Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus.

Highlights

Kefir is a fermented beverage consumed since ancient times that presents typical flavour characteristics through the presence of lactic and acetic acids, ethanol, and carbon dioxide
We previously reported the Angiotensin converting enzyme (ACE) inhibitory and antibacterial activities of sugary kefir made from various types of sugar solution, and demonstrated that these activities were significantly enhanced after fermentation [12]. e microbial and chemical compositions of kefir, as well as the way they change during fermentation, are important in determining the above benefits as a functional food
Carbohydrate concentration decreased in both kefirs due to microbial consumption. e main sugars utilised by microbes were lactose for cow’s milk kefir and sucrose for soy milk kefir (Table 3)

Summary

Introduction

Kefir is a fermented beverage consumed since ancient times that presents typical flavour characteristics through the presence of lactic and acetic acids, ethanol, and carbon dioxide. E main raw material for kefir, cow’s milk, is consumed worldwide, with a total production of 770bn litres in 2013, equivalent to USD$328bn, as the top agricultural commodity [5]. For various reasons some people do not consume milk: they may be vegan or have health problems such as lactose intolerance or casein allergy. Cardiovascular disease accounts for approximately 17 million deaths per year worldwide. Within this value, complications of hypertension cause 9.4 million deaths worldwide annually. Erefore, research on foods containing ACE inhibitory compounds has become important in the hope of counteracting this public health problem. Antioxidant activity is another important food function.

Methods

Results

Discussion

Conclusion