啤酒废酵母制备犬粮诱食剂的研究及其应用

发布时间：2018-09-07 16:20

【摘要】：犬粮诱食剂是添加于犬粮中的特殊添加物,可改善犬粮的适口性,增强犬的食欲,提高采食量,并促进犬粮的消化吸收与利用。目前,国内外学者研究发现甜味剂、氨基酸和油脂可提高犬粮适口性,而有关提高犬粮适口性的关键风味化合物却鲜有报道。本文通过分析犬粮及犬粮诱食剂中挥发性成分与其适口性的关系确定提高犬粮适口性的关键风味化合物,继而以关键风味化合物含量为指标优化啤酒废酵母制备犬粮诱食剂的工艺条件,最后研究了自制诱食剂的应用效果。主要研究内容和结果如下:选取市场上7种主流不同层次犬粮(DF)和4种不同风味的犬粮诱食剂(DA),通过适口性测试分别确定了犬粮及犬粮诱食剂的适口性顺序。为进一步探讨产生适口性差异的原因,采用SPME-GC-MS测定其挥发性成分,7种犬粮中检测到56种风味化合物,4种犬粮诱食剂中检测到78种风味化合物。通过偏最小二乘回归(PLSR)模型将产品的适口性与其挥发性化合物进行相关性分析,结果表明提高犬粮适口性的关键风味化合物主要为醛类、杂环等化合物。犬粮及犬粮诱食剂的PLSR分析中均发现辛醛、苯甲醛、乙基香兰素、香兰素、茴香醚、特丁基对苯二酚和乙基麦芽酚为提高犬粮适口性的关键风味化合物。对关键风味化合物中的壬醛(63.80μg/g)、苯甲醛(29.13μg/g)、糠醛(5.20μg/g)、香兰素(50.56μg/g)、乙基麦芽酚(44.05μg/g)和2,5-二甲基吡嗪(4.00μg/g)进行反添加验证测试,其添加量根据样品含量的最大差值确定,结果显示添加2,5-二甲基吡嗪和香兰素的采食率可达75%以上,添加糠醛、苯甲醛和乙基麦芽酚的采食率可达65%以上,添加壬醛的采食率为60%左右。关键化合物主要为醛类和杂环化合物,可通过美拉德反应制备,美拉德反应是指氨基酸和还原糖之间的羟胺反应。首先,选择啤酒废酵母自溶液为氨基酸来源,以水解度为参考指标确定了自溶工艺最佳条件:45 oC,p H 6.5,3倍于酵母泥的蒸馏水,0.3%风味蛋白酶(2.2×104 U/g),自溶时间20 h。在此最佳工艺条件下获得的自溶液中游离氨基酸含量可达40%,其中半胱氨酸和甲硫氨酸的水解率均为90%以上,可应用于美拉德反应制备热反应风味剂。添加反应物(木糖)、重要风味前体物质(硫胺素)和风味增强剂(维生素C),由于含硫氨基酸含量均低于0.5 g/100g,额外添加L-半胱氨酸盐酸盐进行美拉德反应,采用SPME-GC-MS测定关键风味物质含量确定犬粮诱食剂配方:添加3.0%木糖、0.5%L-半胱氨酸盐酸盐、1.5%硫胺素和0.5%维生素C。继而确定美拉德反应条件:120°C,p H 8.0,1 h。最后,加入阿拉伯胶和麦芽糊精混合均匀并喷雾干燥获得粉末状诱食剂产品。通过适口性偏好性测试检验自制犬粮诱食剂的应用效果,结果显示其处于中间水平。可加入关键风味化合物提高其适口性至中上水平,并将改良诱食剂应用于市售犬粮中,其结果显示可显著提高6种市售犬粮的适口性。油脂氧化程度及微生物数是犬粮稳定性的重要评价标准,受p H值影响较大。以POV值和菌落总数为指标考察了诱食剂p H值(2~6)对犬粮储藏稳定性的影响。POV值测定结果表明,犬粮表面喷涂诱食剂后其POV值显著下降,测定不同p H值诱食剂的DPPH自由基清除率和还原力表明诱食剂具有抗氧化性,且p H值较高时,其DPPH自由基清除率较高,p H值为4时,其还原力最强。菌落总数结果表明,犬粮喷涂诱食剂后其菌落总数从103降至102,通过抑菌圈实验表明随着p H值的升高,对大肠杆菌的抑菌效果逐渐增强,而对金黄色葡萄球菌的抑菌效果逐渐减弱。最后通过偏好性测试表明诱食剂的p H值在一定程度变化对适口性无显著影响。最后确定诱食剂的p H值为4。
[Abstract]:Dog food attractant is a special additive added to dog food. It can improve the palatability of dog food, enhance the appetite of dogs, increase the intake of food, and promote the digestion, absorption and utilization of dog food. In this paper, the relationship between volatile components and palatability of dog food and dog food attractants was analyzed to determine the key flavor compounds for improving the palatability of dog food. Results: The main contents and results were as follows: The palatability order of 7 kinds of mainstream dog food (DF) and 4 kinds of dog food attractants (DA) with different flavors were determined by palatability test. The volatile components of DF and DA were determined by SPME-GC-MS in order to further explore the reasons of palatability differences. 56 flavor compounds were detected in dog food and 78 flavor compounds were detected in four dog food attractants. The correlation between palatability and volatile compounds was analyzed by partial least squares regression (PLSR) model. The results showed that the key flavor compounds to improve the palatability of dog food were mainly aldehydes and heterocyclic compounds. Octanaldehyde, benzaldehyde, ethyl vanillin, vanillin, anisole, terbutyl hydroquinone and ethyl maltol were found to be the key flavor compounds for improving the palatability of dog food by PLSR analysis. Nonaldehyde (63.80 ug/g), benzaldehyde (29.13 ug/g), furfural (5.20 ug/g), vanillin (50.56 ug/g), ethyl maltol were found to be the key flavor compounds for improving the palatability of dog food. Maltol (44.05 ug/g) and 2,5-dimethylpyrazine (4.00 ug/g) were tested for validation of reverse addition. The addition amount was determined according to the maximum difference of sample content. The results showed that the intake rate of 2,5-dimethylpyrazine and vanillin was over 75%. The intake rate of furfural, benzaldehyde and ethylmaltol was over 65%. The intake rate of non-aldehyde was over 65%. Maillard reaction refers to the hydroxylamine reaction between amino acids and reducing sugars. Firstly, the autolysis technology of waste beer yeast was selected as the source of amino acids, and the hydrolysis degree was taken as the reference index to determine the optimum conditions: 45oC, P H 6.5, 3. The content of free amino acids in distilled water, 0.3% flavor protease (2.2 *104 U/g) and 20 h autolysis time were obtained. The hydrolysis rates of cysteine and methionine were above 90% and could be used in Maillard reaction to prepare thermal flavoring agent. To obtain the flavor precursor (thiamine) and flavor enhancer (vitamin C), the content of sulfur amino acid was lower than 0.5 g/100g, and L-cysteine hydrochloride was added for Maillard reaction. SPME-GC-MS was used to determine the content of key flavor substances to determine the formula of dog food attractant: adding 3.0% xylose, 0.5% L-cysteine hydrochloride, 1.5% thiamine. And 0.5% vitamin C. Then Maillard reaction conditions were determined: 120 degree C, P H 8.0, 1 h. Finally, the powder food attractant was obtained by mixing Arabic gum and maltodextrin and spraying drying. The application effect of the self-made dog food attractant was tested by palatability preference test, and the results showed that it was in the middle level. The results showed that the palatability of six kinds of commercial dog food could be significantly improved by using the modified attractant. The oxidation degree of oil and the number of microorganisms were important criteria for evaluating the stability of dog food, which were greatly influenced by the P H value. The POV value and the total number of bacteria colonies were used as indicators to investigate the attractant P H. The results of POV value determination showed that POV value decreased significantly after spraying predator on the surface of dog food. The DPPH free radical scavenging rate and reducing power of predator with different P H values showed that predator had antioxidant activity, and DPPH free radical scavenging rate was higher when p H value was higher, and its reducing power was the highest when p H value was 4. The total number of colonies showed that the total number of colonies decreased from 103 to 102. The bacteriostatic effect on E. coli and Staphylococcus aureus gradually increased with the increase of P H, and the bacteriostatic effect on Staphylococcus aureus gradually decreased. Finally, the preference test showed that the P H value of the bait decreased to a certain extent. The change had no significant effect on palatability. Finally, the P H value of the attractant was determined to be 4..
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S816.7;TQ926.4

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