ORIGINAL RESEARCH article
Front. Bioeng. Biotechnol.
Sec. Industrial Biotechnology
Optimization of Solid-State Fermentation Conditions for High β-Galactosidase-Producing Lactic Acid Bacteria and Its Application in Low-Lactose Dairy Products
Provisionally accepted
- MDPI, Tianjin, China
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Lactose intolerance affects 85-95% of Chinese adults, creating substantial demand for low-lactose dairy products. This study aimed to develop a cost-effective β-galactosidase production process through solid-state fermentation (SSF) using agricultural byproducts. A high-yielding strain, Lactobacillus plantarum LP-15, was isolated from Tibetan fermented yak milk, showing initial enzyme activity of 44.7 U/g. Through Box-Behnken response surface methodology, optimal SSF conditions were determined: substrate ratio of wheat bran: soybean meal: whey powder (6:3:1), 37°C, pH 6.5, and 55% moisture content. This optimization achieved enzyme activity of 186.3 U/g, representing a 4.17-fold improvement. The enzyme exhibited optimal activity at pH 6.5 and 42°C, with suitable stability for dairy processing. Milk lactose was reduced by 81.9% within 4 hours using 2.0 U/mL enzyme at 40°C, meeting the Chinese national standard for low-lactose dairy products (≤0.1% lactose according to EU Regulation No 1169/2011). Techno-economic analysis revealed SSF reduced production costs by 35.7% compared to liquid fermentation, with internal rate of return reaching 28%. The process decreased water usage by 94% and CO2 emissions by 62.4%, demonstrating excellent environmental benefits. This study provides an economically viable and environmentally sustainable solution for low-lactose dairy production in China, breaking foreign technology monopoly while addressing nutritional needs of lactose-intolerant populations.
Keywords: β-galactosidase, Lactobacillus plantarum, solid-state fermentation, low-lactose dairy products, Response Surface Methodology
Received: 19 Sep 2025; Accepted: 18 Nov 2025.
Copyright: © 2025 Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Zhanjia Zhang, krfy4175@outlook.com
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