Wätjen Anders Peter, Øzmerih Süleyman, Shetty Radhakrishna, Todorov Sanne Kjærulf, Huang Wenkang, Turner Mark S, Bang-Berthelsen Claus Heiner
National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark.
School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia.
Int J Food Microbiol. 2023 Dec 2;406:110400. doi: 10.1016/j.ijfoodmicro.2023.110400. Epub 2023 Sep 16.
Brewers' spent grain (BSG) is a major side-stream from the beer industry, with an annual estimated production of 39 million tons worldwide. Due to its high nutritional value, high abundance and low price, it has been proposed as an ingredient in human food. Here we investigated the ability of different lactic acid bacteria to produce the flavor molecule acetoin in liquid BSG extract, in order to broaden the possibilities of utilization of BSG in human food. All the investigated lactic acid bacteria (LAB) covering the Leuconostoc, Lactobacillus and Lactoccocus species were able to convert the fermentable sugars in liquid BSG into acetoin. Production levels varied significantly between the different LAB species, with Leuconostoc pseudomesenteroides species reaching the highest titers of acetoin with only acetate as the main byproduct, while also being the fastest consumer of the fermentable sugars present in liquid BSG. Surprisingly, the currently best investigated LAB for acetoin production, L. lactis, was unable to consume the maltose fraction of liquid BSG and was therefore deemed unfit for full conversion of the sugars in BSG into acetoin. The production of acetoin in Leu. pseudomesenteroides was pH dependent as previously observed in other LAB, and the conversion of BSG into acetoin was scalable from shake flasks to 1 L bioreactors. While all investigated LAB species produced acetoin under aerobic conditions, Leu. pseudomesenteroides was found to be an efficient and scalable organism for bioconversion of liquid BSG into a safe acetoin rich food additive.
啤酒糟（BSG）是啤酒工业的一种主要副产物，全球年产量估计为3900万吨。由于其营养价值高、含量丰富且价格低廉，它被提议作为人类食品的一种成分。在此，我们研究了不同乳酸菌在液体BSG提取物中产生风味分子乙偶姻的能力，以拓宽BSG在人类食品中的利用可能性。所有被研究的乳酸菌（LAB），包括明串珠菌属、乳杆菌属和乳球菌属，都能够将液体BSG中的可发酵糖转化为乙偶姻。不同LAB菌种之间的产量水平差异显著，类肠膜明串珠菌产生的乙偶姻滴度最高，且仅以乙酸作为主要副产物，同时也是液体BSG中可发酵糖的最快消耗者。令人惊讶的是，目前研究最多的用于乙偶姻生产的LAB，乳酸乳球菌，无法消耗液体BSG中的麦芽糖部分，因此被认为不适合将BSG中的糖完全转化为乙偶姻。类肠膜明串珠菌中乙偶姻的产生如先前在其他LAB中所观察到的那样依赖于pH值，并且将BSG转化为乙偶姻可从摇瓶放大至1 L生物反应器。虽然所有被研究的LAB菌种在有氧条件下都能产生乙偶姻，但类肠膜明串珠菌被发现是一种高效且可放大的微生物，可将液体BSG生物转化为一种安全的富含乙偶姻的食品添加剂。
