Institute of Brewing and Beverage Technology, Technical University Munich, 85354, Freising, Germany.
Research Center Weihenstephan for Brewing and Food Quality, Technical University Munich, 85354, Freising, Germany.
Microb Cell Fact. 2024 Sep 19;23(1):253. doi: 10.1186/s12934-024-02522-x.
The market for beverages is highly changing within the last years. Increasing consumer awareness towards healthier drinks led to the revival of traditional and the creation of innovative beverages. Various protein-rich legumes were used for milk analogues, which might be also valuable raw materials for refreshing, protein-rich beverages. However, no such applications have been marketed so far, which might be due to unpleasant organoleptic impressions like the legume-typical "beany" aroma. Lactic acid fermentation has already been proven to be a remedy to overcome this hindrance in consumer acceptance.
In this study, a statistically based approach was used to elucidate the impact of the fermentation parameters temperature, inoculum cell concentration, and methionine addition on the fermentation of lupine- and faba bean-based substrates. A total of 39 models were found and verified. The majority of these models indicate a strong impact of the temperature on the reduction of aldehydes connected to the "beany" impression (e.g., hexanal) and on the production of pleasantly perceived aroma compounds (e.g., β-damascenone). Positively, the addition of methionine had only minor impacts on the negatively associated sulfuric compounds methional, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Moreover, in further fermentations, the time was added as an additional parameter. It was shown that the strains grew well, strongly acidified the both substrates (pH ≤ 4.0) within 6.5 h, and reached cell counts of > 9 log CFU/mL after 24 h. Notably, most of the aldehydes (like hexanal) were reduced within the first 6-7 h, whereas pleasant compounds like β-damascenone reached high concentrations especially in the later fermentation (approx. 24-48 h).
Out of the fermentation parameters temperature, inoculum cell concentration, and methionine addition, the temperature had the highest influence on the observed aroma and taste active compounds. As the addition of methionine to compensate for the legume-typical deficit did not lead to an adverse effect, fortifying legume-based substrates with methionine should be considered to improve the bioavailability of the legume protein. Aldehydes, which are associated with the "beany" aroma impression, can be removed efficiently in fermentation. However, terminating the process prematurely would lead to an incomplete production of pleasant aroma compounds.
近年来，饮料市场变化迅速。消费者对更健康饮料的意识不断提高，促使传统饮料复苏，并创造了创新型饮料。各种富含蛋白质的豆类被用于制作牛奶替代品，这些替代品也可能是清爽、富含蛋白质的饮料的有价值的原料。然而，到目前为止，还没有此类应用推向市场，这可能是由于消费者对不愉快的感官印象（如豆类特有的“豆腥味”）难以接受。乳酸发酵已被证明是克服这一消费者接受障碍的有效方法。
在这项研究中，采用基于统计学的方法来阐明发酵参数（温度、接种细胞浓度和蛋氨酸添加）对羽扇豆和蚕豆基基质发酵的影响。共发现并验证了 39 个模型。这些模型中的大多数表明，温度对降低与“豆腥味”有关的醛（如己醛）和产生令人愉悦的香气化合物（如β-大马酮）有很强的影响。令人欣慰的是，蛋氨酸的添加对与硫磺有关的化合物（如甲硫醛、二甲基硫、二甲基二硫化物和二甲基三硫化物）的负面影响较小。此外，在进一步的发酵中，还增加了时间作为一个额外的参数。结果表明，菌株在两种基质中生长良好，在 6.5 小时内将 pH 值降低到≤4.0，在 24 小时后达到>9 个对数 CFU/mL 的细胞计数。值得注意的是，大多数醛（如己醛）在最初的 6-7 小时内被还原，而β-大马酮等令人愉悦的化合物在后期发酵（约 24-48 小时）中达到较高的浓度。
在发酵参数（温度、接种细胞浓度和蛋氨酸添加）中，温度对观察到的香气和味觉活性化合物的影响最大。由于添加蛋氨酸来弥补豆类特有的缺陷并没有产生不利影响，因此应该考虑在豆类基质中添加蛋氨酸，以提高豆类蛋白的生物利用度。在发酵过程中可以有效地去除与“豆腥味”有关的醛，但过早终止发酵过程会导致令人愉悦的香气化合物不完全生成。
