Mary-Grace C. Danao
Date of this Version
R. Coggins, & M. C. Danao, High Pressure Processing of Cashew Milk, UNL Digital Commons, 2022.
Plant-based foods are becoming increasingly popular because of changing consumer preferences. Most plant-based milks are not a direct replacement for cow’s milk because they do not have the same nutritional value and physicochemical properties. However, these properties could be modified and enhanced through processing. For example, high pressure processing (HPP) can affect irreversibly protein structure and functionality and potentially enhance enzymatic hydrolysis. HPP is used widely in the beverage industry for cold pasteurization. In this study, the effects of HPP treatment on (a) the inactivation of Listeria innocua, a commonly used surrogate for Listeria monocytogenes in HPP research, in cashew milk, (b) enzymatic hydrolysis and (c) foaming capacity of the milk were examined.
Cashew milk was inoculated with two strains of L. innocua and treated in a Hiperbaric 55L HPP machine at the following conditions: (a) 300 MPa using chilled water (approximately 4-5 °C), (b) 590 MPa using chilled water, and (c) 590 MPa using room temperature water (approximately 19-22 °C). All pressures were held for 6 min. Results showed that treating the milk with 590 MPa for 6 min using either chilled or room temperature water yielded at least a 5-log reduction in L. innocua. When pressure-treated using chilled water, L. innocua was able to recover by at least 2 log CFU/mL after 14 days of refrigerated storage, which is comparable to the shelf-life of heat-pasteurized cow’s milk. Remarkably, when pressure-treated at room temperature, L. innocua counts were still below the limit of detection (1 log CFU/mL) even after 35 days.
Cashew milk samples were treated with 150, 300, 450 and 600 MPa for 6 min using chilled water. Results showed pressure had minimal effect on protein profiles obtained by gel electrophoresis but increased the peptide content (F = 42.1719; df = 5, 18.2053; p = 2.185 ´ 10-9). Alcalase® activity was not affected by HPP treatment (F = 0.4432; df = 4, 8; p = 0.7749). However, when Alcalase® was added to the milk (0.01% v/v) immediately prior to HPP treatment, the resulting protein profiles showed visible band shifts. Peptide content also increased significantly (F = 17.1944; df = 1, 4.45; p = 0.0114). Foaming capacity significantly decreased with Alcalase® presence and HPP treatment (F = 6.6873; df = 4, 18.1613; p = 0.001723).
Advisor: Mary-Grace C. Danao