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. 2018 Jan 8;7(1):6.
doi: 10.3390/foods7010006.

Comparison of Conventional and Microwave Treatment on Soymilk for Inactivation of Trypsin Inhibitors and In Vitro Protein Digestibility

Brinda Harish Vagadia  1 , Sai Kranthi Vanga  2 , Ashutosh Singh  3 , Yvan Gariepy  4 , Vijaya Raghavan  5
Affiliations

Comparison of Conventional and Microwave Treatment on Soymilk for Inactivation of Trypsin Inhibitors and In Vitro Protein Digestibility

Brinda Harish Vagadia et al. Foods. .

Abstract

Soymilk is lower in calories compared to cow's milk, since it is derived from a plant source (no cholesterol) and is an excellent source of protein. Despite the beneficial factors, soymilk is considered as one of the most controversial foods in the world. It contains serine protease inhibitors which lower its nutritional value and digestibility. Processing techniques for the elimination of trypsin inhibitors and lipoxygenase, which have shorter processing time and lower production costs are required for the large-scale manufacturing of soymilk. In this study, the suitable conditions of time and temperature are optimized during microwave processing to obtain soymilk with maximum digestibility with inactivation of trypsin inhibitors, in comparison to the conventional thermal treatment. The microwave processing conditions at a frequency of 2.45 GHz and temperatures of 70 °C, 85 °C and 100 °C for 2, 5 and 8 min were investigated and were compared to conventional thermal treatments at the same temperature for 10, 20 and 30 min. Response surface methodology is used to design and optimize the experimental conditions. Thermal processing was able to increase digestibility by 7% (microwave) and 11% (conventional) compared to control, while trypsin inhibitor activity reduced to 1% in microwave processing and 3% in conventional thermal treatment when compared to 10% in raw soybean.

Keywords: microwave processing; response surface methodology; soymilk; thermal processing; trypsin inhibitors.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effect of time (min) and temperature (°C) on in vitro protein digestibility (IVPD) of soymilk during microwave processing.
Figure 2
Figure 2
Effect of time (min) and temperature (°C) on in vitro protein digestibility (IVPD) of soymilk during conventional thermal treatment.
Figure 3
Figure 3
Effect of time (min) and temperature (°C) on trypsin inhibitor activity (TIA) of soymilk during microwave processing.
Figure 4
Figure 4
Effect of time (min) and temperature (°C) on trypsin inhibitor activity (TIA) of soymilk during conventional thermal treatment.
See this image and copyright information in PMC

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