Optimization of Lentilactobacillus buchneri Mediated Fermentation for Valorizing Tea By-Products into Feed: Process Parameters, Nutritional Quality Enhancement, and Bacterial Community

The massive annual production of tea generates substantial underutilized by-products, leading to resource waste. This study aimed to develop an efficient process for converting these by-products into high-quality feed via fermentation with Lentilactobacillus buchneri (L. buchneri). Using a response surface methodology, the key fermentation parameters (time, temperature, inoculum size, and moisture) were optimized to target pH and crude protein (CP) content. The optimal conditions (4.5 days, 34.5 °C, 5.00 × 106 CFU/g, 54% moisture) yielded a product with a pH of 3.72 and CP content of 17.96%, which was similar to the predictions. Fermentation successfully reduced ether extract (EE), tea tannin (TTN), and propionic acid (PA), while increasing lactic acid (LA) and lowering pH. This process was driven by the dominance of Lactobacillus (99.29% relative abundance), as revealed by microbial analysis. This work provides a viable and optimized strategy for valorizing tea by-products into nutritionally enhanced feed, thereby contributing to sustainable agricultural practices.