Lactose sugar is a source of energy for Lactic Acid Bacteria (LAB) in dairy fermented products. Enrichment of yogurt with lactose addition may increase growth and viability of the yogurt starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus) and enhance yogurt physico-chemical and sensory attributes. The objectives of this study were: to determine the influence of added lactose on (1) acid and bile tolerance of yogurt starter culture Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12, (2) the final lactose content of yogurt during its shelf life, (3) the physico-chemical characteristics of yogurt during shelf life, (4) the growth of the yogurt starter culture during yogurt´s shelf life and (5) the sensory attributes of yogurt. Acid tolerance test was conducted on pure culture at 30 minutes intervals for 2 hours of incubation period and bile tolerance at 1 hour intervals during 12 hours. Fat free plain set-type yogurt was manufactured using 0, 1, 3 and 5% w/w added lactose to accomplish objectives 2, 3 and 4. For objective 5, a blueberry yogurt was manufactured using the same lactose levels. Analyses for plain set-type yogurt were done at 7 days intervals during 35 days of storage period. Sensory evaluation was conducted on yogurt 3 days after its manufacture. Data were analyzed using Proc Mixed model of SAS® 9.3 program and by analysis of variance (ANOVA) using Proc GLM. Significant differences between means were analyzed at α = 0.05 using Tukey´s adjustment. Lactose had a positive effect on acid tolerance and bile tolerance of both yogurt starter cultures, growth of S. thermophilus and sensory attributes of flavored yogurt. Mean overall liking scores were higher for samples containing added lactose compared to control as tested by 100 panelists. Lactose supplementation in yogurt might be a good approach to increase its health benefits, acceptability and purchase intent among consumers.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-07052013-151800 |
| Date | 12 July 2013 |
| Creators | Mena-Chalas, Behannis Jasmin |
| Contributors | Aryana, Kayanush J, Janes, Marlene E, Boeneke, Charles August |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-07052013-151800/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.002 seconds