Effects of high hydrostatic pressure treatment on allergenicity and structural properties of soybean protein isolate for infant formula

• Published in: Food chemistry 2012-05, Vol.132 (2), p.808-814
• Main Authors: Li, Huijing, Zhu, Kexue, Zhou, Huiming, Peng, Wei
• Format: Article
• Language: English
• Subjects: Allergenicity; Biological and medical sciences; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; High hydrostatic pressure (HHP); Soybean protein isolate (SPI); Structural properties
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2011.11.040

► HHP treatment could reduce allergenicity of SPI for infant formula. ► The determinants of soy allergens were complexes in current study. ► HHP could alter allergen interactions such as free SH content and hydrophobicity. ► HHP could interfere with secondary structures of soy allergens. ► HHP could decrease allergenicity by modifying conformation of allergenic epitopes. The objective of this study is to investigate the influences of HHP treatment on the allergenic properties of SPI for infant formula. The processing parameters, including HHP pressure and duration time, could significantly influence the allergenicity reducing efficiency. At 300MPa and 15min, the allergenicity decreased 48.6%, compared to the native SPI. In the ranges of 200–300MPa and 5–15min, the free SH content and hydrophobicity of SPI significantly increased. Meanwhile, at the levels above 300MPa and 15min, the two interactions progressively decreased. Whatever HHP pressure and time, the maximum emission wavelength indicated blueshifts. At 300MPa and 15min, there was an 11.5-fold increase in fluorescence intensity and the maximum emission wavelength shifted from 516 to 466nm. After HHP treatment, the helix1 and turns content, significantly increased and the strand1 and unordered content considerably decreased; whereas the amount of the helix2 and strand2 did not indicate any obvious change. The average length of helices significantly increased, while the helices (per 100 residues) did not strikingly change after HHP modification. However, both the strand (per 100 residues) and the average length of strands clearly decreased. Some documents indicate that the epitopes of SPI allergens could be closely related to the secondary structure of α-helix and β-sheet. These interactions and secondary structure results can provide direct evidence, or explanation, for HHP-induced modification of soy proteins, which could alter the allergenicity of SPI and enhance the security of SPI for cow milk allergic babies.