Pulsed high-pressure processing of barley-based non-dairy alternative milk: β-carotene retention, protein solubility and antioxidant activity

Abstract

Emerging technologies have been investigated as smart process options for manufacturing plant-based non-dairy alternative milk. However, few studies have evaluated the effects of these non-conventional technologies on the preservation of bioactive and nutritional compounds. In this regard, this study aimed to examine the impact of pulsed high-pressure processing at non-thermal and thermal conditions on the quality parameters of barley-based non-dairy milk enriched with β-carotene. The effects of the pressure (100, 300, and 600 MPa), number of pulses (1, 2, and 3 at 100 and 300 MPa), and temperature (40 and 80 °C) on the soluble protein content, β-carotene retention, total phenolic content, and flavonoid content were assessed. Also, we examined the antioxidant capacity of the samples using in vitro assays. The samples were exposed to pressure for 2 min, but the total treatment time varied from 2.5 to 9 min, according to the pressure and pulse conditions. Higher pressure pulses at 100 MPa favored the homogenization of the system. The solubility of the barley proteins increased by increasing the number of pulses from 1 to 3 at 100 MPa. β-Carotene was thermally degraded up to 20% by the thermal treatments at 80 °C. Additionally, the treatments performed at 80 °C provided samples with lower phenolic and flavonoid contents. On the other hand, the rise in pressure up to 300 MPa promoted the disruption of the cell membranes of barley particles, favoring the extraction of bonded phenolic and flavonoid compounds. Regardless of the number of pulses, samples treated at 300 MPa and 40 °C presented the highest phenolic and flavonoid contents. Antioxidant capacity results presented similar behavior as observed for phenolic and flavonoid contents. Therefore, the different combinations of pressure and temperature promoted distinct effects on the protein solubility and bioactive compounds of the barley-based non-dairy milk.