"Phytochemicals and Flavor Profiles of Soymilk" by Vandana Panchal

Document Type

Thesis - University Access Only

Award Date

2009

Degree Name

Master of Science (MS)

Department / School

Nutrition, Food Science, and Hospitality

Abstract

Soymilk has increased its popularity in food market and received a widespread attention because of its numerous health benefits. Some of the numerous health benefits of soymilk include preventive effects against various types of cancer, reduced risk of coronary heart diseases, chronic diseases, and hormone related diseases. In spite of having a good nutritional profile and rapid increase in the market demand, soymilk consumption is still less than 1 % of all dairy milk products consumption. One of the main drawbacks of soymilk is the limited acceptance by the consumers due to the unpleasant flavor profile developed sometimes during processing or storage. The compounds responsible for the undesirable flavor profile of soymilk include lipoxygenase, isoflavone aglucones, and saponins. The objectives of this study were: (1) to study the effect of two processing methods (traditional method, VitaCow® system) on the phytochemicals, and flavor profile of soymilk.(2)To study the change in the phytochemical and flavor profile of the soymilk with storage.(3) To establish a correlation if exists, between the change in the concentration soy phytochemicals (isoflavones ), and flavor attributes of soymilk (beany flavor, off-flavor, astringency, aftertaste, bitterness, and oxidized flavor) with the storage period of 12 days at refrigeration temperature. Soymilk was processed with two different methods traditional method, and VitaCow® system, and stored in sterilized glass jars. Sensory analysis (using descriptive analysis) and isoflavone analysis (using HPLC) was done on each 15\ 4th, 8th, and 12th day of storage. When comparing the phytochemical, and sensory profile of the soymilk processed with the two methods (traditional method, VitaCow® system), the soymilk processed with traditional method had, lower total malonyl glucosides (P:S0.05), higher total aglucones (P:S0.05), and lower total glucosides (P:S0.05). The soymilk processed with traditional method reported higher sensory scores for, oxidized flavor (P:S0.05), off-flavor (P:S0.05), and beany flavor (P:S0.05). The longer duration of grinding and cooking at lower temperature might have lead to the hydrolysis of isoflavone glucosides, which can be the major cause of the higher aglucone content in the soymilk processed with traditional method. This might contribute to the flavor profile of traditionally processed soymilk. The storage studies showed no significant difference in the concentration of isoflavones (P2'.:0.05) with storage. However, there was slight reduction in the concentration of isoflavone glucosides, and increase in the concentration of isoflavone aglucones. The sensory results showed a significant increase (P:S0.05) in the scores of all six flavor attributes (beany flavor, off-flavor, astringency, aftertaste, bitterness, and oxidized flavor) within the storage period of 12 days. Strong correlation was observed between genistein and beany flavor for the soymilk processed with both VitaCow® system (R2=0.8261) and traditional method (R2=0.8293). Similarly a strong correlation was observed between genistein and aftertaste for the soymilk processed with both VitaCow® system (R2= 0.7165), and traditional method (R2= 0.7643). For other flavor attributes a weak correlation values were obtained. The study concludes that there is a correlation between the change in the photochemical profile and change in the flavor attributes of the soymilk with storage. Soy saponins are other class of phytochemicals present in soymilk which are reported to have undesirable flavor attributes. Further research can be conducted on the effect of different forms of saponins on the flavor of soymilk. The study provided foundation for future studies that can improve flavor profiles of soymilk by controlling changes in phytochemicals.

Library of Congress Subject Headings

Soymilk

Phytochemicals

Flavor

Format

application/pdf

Number of Pages

102

Publisher

South Dakota State University

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