Journal Review: The Effect of Milk Type, Extract Addition, Starter Concentrate, and Fermentation Time on pH and Lactid Acid Bacteria in Kefir

Abstract

Kefir is a fermented beverage that has the potential as a functional food because it contains lactic acid bacteria (LAB) which are beneficial for health. This review aims to analyze the effect of various types of milk and the addition of these ingredients on the characteristics of kefir based on pH parameters and the number of LAB. The method used is a literature study by reviewing various relevant research journals on kefir production and characteristics. A number of studies have examined the production of kefir using various types of milk—such as cow, goat, buffalo, and soy milk—as well as the addition of various natural ingredients, such as cow's milk, goat's milk, buffalo milk, and soy milk, as well as the addition of various natural ingredients, including maja leaf extract, skim milk, gerga orange juice, dragon fruit juice, black rice, sunflower seeds, ginger extract, and pandan leaves. The results of the study indicate that the type of milk and the addition of extracts affect the pH value and the number of LAB. The type of milk increases the growth of LAB and pH varies because the nutritional content that supports the activity of fermentation microorganisms varies, while the addition of extracts or fruit juices containing sugar, bioactive compounds, and antioxidants can affect fermentation activity, resulting in variations in pH values and the number of LAB. Based on the results of various studies, it can be concluded that the combination of milk type and additives plays a significant role in determining the microbiological characteristics and acidity level of kefir, thus providing a basis for developing better-quality kefir products.