燕麦酸面团发酵剂的冻干和储藏对面包风味的影响

应用固相微萃取技术(SPME)和气相色谱- 质谱联用技术(GC-MS)研究发酵剂冷冻干燥(冻干)前后面包中的挥发性风味物质，考察发酵剂的冻干和储藏对燕麦酸面包风味的影响。结果表明：旧金山乳杆菌发酵燕麦酸面包中的挥发性风味物质共87 种，主要包括酸类、醇类、醛类、酯类、酮类、脂肪烃类，以及一些芳香族和杂环类化合物。酸类物质的含量最高，其次是醇类、芳杂环类和醛类物质。在发酵剂冻干和储藏过程中，醛类和醇类物质先增加后减少，酸类、酯类、酮类和脂肪族化合物先减少后增加，芳杂环类物质含量则持续升高。燕麦酸面团发酵剂冻干后以及储存30d 制得的面包依然具有丰富的风味。乳酸菌和酵母菌的竞争作用导致乙酸和乙醇含量呈现相反的变化。糠醛含量持续升高，而己醛则在冻干后显著减少，并在存储30d 后消失。

Effects of Freeze Drying and Storage of Oat Sourdough Starter on Volatile Flavor Compounds of Bread

Oat breads made with non-freeze-dried L.sanfranscensis containing sourdough starter and freeze-dried ones stored at 4 ℃ for 0 and 30 days were analyzed for their volatile compound composition by solid phase micro-extraction/gas chromatography-mass spectrometry (SPME/GC-MS) in order to explore the effects of freeze drying and storage of sourdough starter on volatile flavor compounds of bread. A total of 87 compounds were identified in the three oat breads and acids, alcohols, aldehydes, aromatic and heterocyclic compounds were of most importance in the volatile profile. The most abundant volatile compound category in all samples was acids, followed by alcohols, aromatic and heterocyclic compounds and aldehydes. Through freeze-drying and subsequent storage, aldehydes and alcohols contents first increased and then decreased; while acid, esters, ketones and aliphatic compounds experienced an opposite process, and the concentration of aromatic and heterocyclic compounds rose up. Breads made with both freeze-dried starters were also rich in volatile flavor compounds. Acetic acid and ethanol contents showed opposite changes due to the competition between L.sanfranscensis and yeast. The relative abundance of furfural increased in both cases. However, hexanal content significantly decreased after freeze-drying and was not detected in bread made with 30-day stored freeze-dried starter.