中国农业科学 ›› 2018, Vol. 51 ›› Issue (10): 1982-1994.doi: 10.3864/j.issn.0578-1752.2018.10.017

• 食品科学与工程 • 上一篇    下一篇

胶红酵母产类胡萝卜素固态发酵工艺

孙佳静(), 李貌, 孙志洪(), 唐志如, 张相鑫, 陈进超   

  1. 西南大学动物科技学院/生物饲料与分子营养实验室,重庆 400715
  • 收稿日期:2017-10-09 接受日期:2018-03-05 出版日期:2018-05-16 发布日期:2018-05-16
  • 联系方式: 联系方式:孙佳静,E-mail:2020853948@qq.com。
  • 基金资助:
    国家自然科学基金(31772610)、重庆市留学人才创新计划重点项目(cx2017024)、农业部“948”项目(2015-Z74)

The Solid-State Fermentation Process of Rhodotorula Mucilaginosa for Producing Carotenoids

JiaJing SUN(), Mao LI, ZhiHong SUN(), ZhiRu TANG, XiangXin ZHANG, JinChao CHEN   

  1. College of Animal Science and Technology/Laboratory for Bio-Feed and Animal Nutrition, Southwest University, Chongqing 400715
  • Received:2017-10-09 Accepted:2018-03-05 Published:2018-05-16 Online:2018-05-16

摘要:

目的 优化胶红酵母固态发酵底物与发酵条件,提高类胡萝卜素产量,改善发酵产物营养价值,降低生产成本。方法 选用胶红酵母TZR2014作为发酵菌种,采用Design-Expert软件的Mixture-Design设计固态发酵底物的配比,各底物原料的范围如下:麸皮50%—80%、豆粕6%—20%、玉米粉3%—15%、米糠2%—14%、玉米浆2%—10%、硫酸铵0.4%—2.5%、磷酸二氢钾0.05%—0.5%和硫酸镁0.03%—0.3%,通过固态发酵工艺生产类胡萝卜素,并根据类胡萝卜素的产量来确定最优的发酵底物。确定最适发酵底物配比后,利用L16(45)正交设计对发酵条件进行优化设计,各参数的范围如下:接种量5.0%—12.5%、发酵时间60.0—96.0 h、发酵温度26—32℃、pH 4.0—7.0、含水量60.0%—75.0%,根据试验结果确定胶红酵母产类胡萝卜素的最优发酵条件。研究优化的胶红酵母固态发酵工艺对发酵产物粗纤维、粗蛋白质、水分、粗脂肪、粗灰分、钙、磷和氨基酸等营养物质的影响。结果 胶红酵母发酵产物中类胡萝卜素含量与固态发酵底物中麦麸的添加量呈显著负相关(r=-0.336,P=0.045),与发酵底物中玉米浆的添加量呈显著正相关(r=0.344,P=0.040),与发酵底物中米糠添加量为正相关(r=0.329,P=0.050)。发酵产物中胶红酵母活菌数与底物中豆粕含量呈显著正相关(r=0.510,P=0.001)。接种量、发酵温度、pH、底物含水量对胶红酵母活菌数均有极显著的影响(P<0.01),但其中发酵温度对胶红酵母菌体数影响最大,其次是底物含水量,之后依次是接种量和pH。发酵时间、发酵温度和pH均显著影响发酵产物中类胡萝卜素含量(P<0.05),其中发酵温度对发酵产物中类胡萝卜素含量影响最大,pH次之,发酵时间影响最小。经过发酵工艺的优化,发酵产物中类胡萝卜素产量提高到4 535 μg·kg-1,发酵产物中的活菌数为3.79×109 CFU/g;发酵后粗纤维、粗蛋白质、粗灰分、苏氨酸、谷氨酸、脯氨酸含量均显著高于发酵前(P<0.05),而组氨酸、水分、粗脂肪含量显著低于发酵前(P<0.05)。结论 胶红酵母固态发酵产类胡萝卜素底物的最佳配比为麦麸52.5%、豆粕20.0%、玉米粉3.00%、米糠14.0%、玉米浆10.0%、硫酸铵0.40%、磷酸二氢钾0.05%和硫酸镁0.04%;最佳发酵条件为菌液接种量5.0%、发酵时间72.0 h、发酵温度28.0℃、pH 6.0、底物含水量60.0%。经过优化胶红酵母发酵工艺,类胡萝卜素产量得到显著提高,并且发酵产物营养价值得到明显改善。

关键词: 胶红酵母, 固态发酵, 类胡萝卜素, 发酵底物, 发酵条件

Abstract:

【Objective】 This study was performed to enhance carotenoid yield, to improve nutritional value of fermentation product, and to reduce the production cost of carotenoids through optimizing solid-state fermentation substrate and fermentation conditions of Rhodotorula mucilaginosa.【Method】 In this study, Rhodotorula mucilaginosa TZR2014 was used as a inoculant. First, the Mixture-Design of Design-Expert software was used to design the fermentation substrate, and the contents of ingredients as followed: 50%-80% wheat bran, 6%-20% soybean meal, 3%-15% maize flour, 2%-14% rice bran, 2%-10% maize syrup, 0.4%-2.5% ammonium sulfate, 0.05%-0.5% monopotassium phosphate, and 0.03%-0.3% magnesium sulfate. Then the optimal ratio of ingredients in substrate was determined according to the carotenoid yield. Based on this result, an L16(45) orthogonal design was used to optimize the fermentation conditions, including inoculum (5.0%-12.5%), fermentation time (60.0-96.0 h), fermentation temperature (26-32℃), and fermentation pH (60.0%-75.0%). Finally, the number of Rhodotorula mucilaginosa and contents of carotenoids, crude fiber, crude protein, water, crude fat, ash, calcium, phosphorus, and amino acids in fermentation product were determined to evaluate the effects of the optimized fermentation process on the nutritional values of fermentation product. 【Result】 The results showed that there was a positive correlation between maize starch content in substrate and carotenoid content in fermentation product (r=0.344, P=0.040) or between rice bran content in fermentation substrate and carotenoid content in fermentation product (r=0.329, P=0.050). There was a significantly negative correlation between carotenoid yield and the content of wheat bran in solid-state fermentation substrate (r=-0.336, P=0.045). There was a positive correlation between the number of live bacteria of Rhodotorula mucilaginosa in fermentation product and the content of soybean meal in fermentation substrate (r=0.510, P=0.001). Inoculum, fermentation temperature, pH, and moisture had extremely significant impacts on the number of Rhodotorula mucilaginosa (P<0.01), thereinto, fermentation temperature had the greatest effect on the number of Rhodotorula mucilaginosa, followed by moisture, inoculum, and pH. Fermentation time, fermentation temperature, and pH had extremely significant influences on the carotenoid content in the fermentention product (P<0.01), and fermentation temperature had the greatest influence on the carotenoid content in the fermented product, followed by pH and fermentation time. After the optimization of the fermentation process, the carotenoid yield by Rhodotorula mucilaginosa TZR2014 was increased to 4 535 μg·kg-1; the bacteria number was increased to 3.79×109 CFU/kg; the contents of crude fiber, crude protein, ash, threonine, glutamate, and proline in fermentation product were significantly increased (P<0.05), meanwhile, the contents of histidine, water, and crude fat was significantly decreased (P<0.05). 【Conclusion】 The optimal ratio of solid-state fermentation substrate for Rhodotorula mucilaginosa was as followed: 52.5% wheat bran, 20.0% soybean meal, 3.0% maize flour, 14.0% rice bran, 10.0% maize syrup, 0.4% ammonium sulfate, 0.05% monopotassium phosphate, and 0.04% magnesium sulfate. The optimal fermentation conditions were as followed: inoculum 5.0%, fermentation time 72 h, fermentation temperature 28.0℃, pH 6.0, and moisture 60.0%. The results suggested that the optimized fermentation process of Rhodotorula mucilaginosa enhanced the yield of carotenoids and improved the nutritional value of fermentation product.

Key words: Rhodotorula mucilaginosa, solid-state fermentation, carotenoids, fermentation substrates, fermentation conditions