Axel Claudia, Brosnan Brid, Zannini Emanuele, Furey Ambrose, Coffey Aidan, Arendt Elke K
School of Food and Nutritional Sciences, University College Cork, Ireland.
Mass Spectrometry Research Centre (MSRC) & Team Elucidate, Department of Chemistry, Cork Institute of Technology, Bishopstown, Cork, Ireland.
Int J Food Microbiol. 2016 Dec 19;239:86-94. doi: 10.1016/j.ijfoodmicro.2016.05.006. Epub 2016 May 7.
The use of sourdough fermented with specific strains of antifungal lactic acid bacteria can reduce chemical preservatives in bakery products. The main objective of this study was to investigate the production of antifungal carboxylic acids after sourdough fermentation of quinoa and rice flour using the antifungal strains Lactobacillus reuteri R29 and Lactobacillus brevis R2Δ as bioprotective cultures and the non-antifungal L. brevis L1105 as a negative control strain. The impact of the fermentation substrate was evaluated in terms of metabolic activity, acidification pattern and quantity of antifungal carboxylic acids. These in situ produced compounds (n=20) were extracted from the sourdough using a QuEChERS method and detected by a new UHPLC-MS/MS chromatography. Furthermore, the sourdough was applied in situ using durability tests against environmental moulds to investigate the biopreservative potential to prolong the shelf life of bread. Organic acid production and TTA values were lowest in rice sourdough. The sourdough fermentation of the different flour substrates generated a complex and significantly different profile of carboxylic acids. Extracted quinoa sourdough detected the greatest number of carboxylic acids (n=11) at a much higher concentration than what was detected from rice sourdough (n=9). Comparing the lactic acid bacteria strains, L. reuteri R29 fermented sourdoughs contained generally higher concentrations of acetic and lactic acid but also the carboxylic acids. Among them, 3-phenyllactic acid and 2-hydroxyisocaproic acid were present at a significant concentration. This was correlated with the superior protein content of quinoa flour and its high protease activity. With the addition of L. reuteri R29 inoculated sourdough, the shelf life was extended by 2 days for quinoa (+100%) and rice bread (+67%) when compared to the non-acidified controls. The L. brevis R2Δ fermented sourdough bread reached a shelf life of 4 days for quinoa (+100%) and rice (+33%). However, the shelf life was similar to the chemically acidified control indicating that the preservation effect of the carboxylic acids seems to have a minor contribution effect on the antifungal activity in gluten-free breads.
使用经特定抗真菌乳酸菌菌株发酵的酸面团可减少烘焙食品中的化学防腐剂。本研究的主要目的是调查以抗真菌菌株罗伊氏乳杆菌R29和短乳杆菌R2Δ作为生物保护培养物，以及以非抗真菌的短乳杆菌L1105作为阴性对照菌株，对藜麦粉和米粉进行酸面团发酵后抗真菌羧酸的产生情况。从代谢活性、酸化模式和抗真菌羧酸的量方面评估了发酵底物的影响。使用QuEChERS方法从酸面团中提取这些原位产生的化合物（n = 20），并通过新型超高效液相色谱-串联质谱法进行检测。此外，通过针对环境霉菌的耐久性测试原位应用酸面团，以研究其延长面包保质期的生物防腐潜力。米粉酸面团中的有机酸产量和总酸度值最低。不同面粉底物的酸面团发酵产生了复杂且差异显著的羧酸谱。提取的藜麦酸面团检测到的羧酸数量最多（n = 11），其浓度远高于米粉酸面团（n = 9）中检测到的浓度。比较乳酸菌菌株，罗伊氏乳杆菌R29发酵的酸面团通常含有较高浓度的乙酸和乳酸以及羧酸。其中，3-苯乳酸和2-羟基异己酸的浓度显著。这与藜麦粉中较高的蛋白质含量及其高蛋白酶活性相关。与未酸化的对照相比，添加罗伊氏乳杆菌R29接种的酸面团后，藜麦面包（+100%）和米面包（+67%）的保质期延长了2天。短乳杆菌R2Δ发酵的酸面团面包，藜麦面包（+100%）和米面包（+33%）的保质期达到了4天。然而，保质期与化学酸化对照相似，这表明羧酸的防腐效果似乎对无麸质面包的抗真菌活性贡献较小。
