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中国精品科技期刊2020
尹新雅,李梦瑶,李呵呵,等. 蛋白谷氨酰胺酶与发酵剂对核桃酸奶品质的影响[J]. 食品工业科技,2024,45(18):128−137. doi: 10.13386/j.issn1002-0306.2023100214.
引用本文: 尹新雅,李梦瑶,李呵呵,等. 蛋白谷氨酰胺酶与发酵剂对核桃酸奶品质的影响[J]. 食品工业科技,2024,45(18):128−137. doi: 10.13386/j.issn1002-0306.2023100214.
YIN Xinya, LI Mengyao, LI Hehe, et al. Effects of Protein-glutaminase and Starter Cultures on the Quality of Walnut-based Yogurt[J]. Science and Technology of Food Industry, 2024, 45(18): 128−137. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023100214.
Citation: YIN Xinya, LI Mengyao, LI Hehe, et al. Effects of Protein-glutaminase and Starter Cultures on the Quality of Walnut-based Yogurt[J]. Science and Technology of Food Industry, 2024, 45(18): 128−137. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023100214.

蛋白谷氨酰胺酶与发酵剂对核桃酸奶品质的影响

Effects of Protein-glutaminase and Starter Cultures on the Quality of Walnut-based Yogurt

  • 摘要: 选用核桃仁为原料,制浆后利用蛋白谷氨酰胺酶对其水解,通过调配、均质、灭菌及发酵制备凝固型核桃酸奶。通过对其发酵特性、理化指标及微观形态等方面的分析,研究蛋白谷氨酰胺酶(protein glutaminase,PG)作用条件和5种直投式发酵剂(Ⅰ~Ⅴ)对核桃酸奶品质的改善效果,并将最佳条件下的核桃酸奶与牛乳酸奶对比。结果表明,相较未酶解的核桃乳,酶解后核桃乳制备的酸奶在发酵特性与质构参数方面得到有效改善,其中添加量0.2%(1.35 U/g)、水解40 min为最佳酶解条件,所制得的核桃酸奶pH为4.3,酸度为55°T,硬度达到85.30 g,稠度为583.96 g·s。采用发酵剂Ⅰ制备的核桃酸奶酸度最高,且在储存期21 d内的变化幅度小,而其他发酵剂制备的酸奶出现了不同程度的分层和沉淀。采用发酵剂Ⅰ发酵的酸奶具有更好的粘弹性,且凝胶网络结构更为致密,而发酵剂Ⅳ和Ⅴ发酵的酸奶表观粘度、G'和G''较小,凝胶结构更为松散。此外,采用发酵剂Ⅰ制备的核桃酸奶在储存期内的活菌数始终高于106 CFU/mL。虽然与牛乳酸奶相比,核桃酸奶在稠度、持水力及乳清析出率方面仍有待改善,但总体来说,PG酶解改善了核桃酸奶的凝乳效果,采用发酵剂Ⅰ(保加利亚乳杆菌和嗜热链球菌)制备出的酸奶品质得到提升,整体评价较好。

     

    Abstract: Walnut kernels, selected as the raw material, underwent hydrolysis with protein-glutaminase (PG) following pulping. This process laid the foundation for producing set-type walnut yogurt, involving steps such as blending, homogenization, sterilization, and fermentation. The study investigated the impact of protein-glutaminase and five distinct starter cultures labeled I~V on the quality of walnut yogurt. This was evaluated by examining the yogurt's fermentation characteristics, physicochemical indicators, and microstructure. Furthermore, walnut yogurt developed under these optimal conditions was compared to traditional milk yogurt to assess its quality and characteristics. The findings revealed a significant improvement in the fermentation characteristics and textural parameters of yogurt fermented by walnut milk following enzymatic hydrolysis compared to non-enzymatic walnut milk. The optimal conditions were identified as 0.2% enzyme concentration and a 40-minute reaction time, with the pH, acidity, hardness, and consistency of walnut yogurt being 4.3, 55°T, 85.30 g, and 583.96 g·s, respectively. Walnut yogurt developed using starter culture I exhibited the highest acidity level, maintaining minimal fluctuation over a 21-day storage period. In contrast, yogurts prepared with alternative starter cultures demonstrated varying degrees of stratification and sedimentation. The yogurt fermented with culture I showed superior viscoelastic properties, presenting a denser gel network. Conversely, yogurts fermented with cultures IV and V displayed reduced apparent viscosity, lower values of G' (storage modulus), and G'' (loss modulus), along with a looser gel structure. Additionally, walnut yogurt produced with starter culture I maintained bacterial counts exceeding 106 CFU/mL throughout the storage duration. Despite walnut yogurt requiring further refinement in aspects such as consistency, water-holding capacity, and whey release rate compared to milk yogurt, the overall impact of PG was positive, enhancing the gelation quality of walnut yogurt. The yogurt prepared with starter culture I (Lactobacillus bulgaricus and Streptococcus thermophilus) was notably improved, receiving favorable overall assessments.

     

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