ABSTRACT
Plant-based foods are being increasingly favored to feed the ever-growing population, but these need to exhibit improved nutritional value in terms of protein quality and digestibility to be considered a useful alternative to animal-based foods. Germination is essential for plant growth and represents a viable method through which the protein quality of plants can be further improved. However, it will be a challenge to maintain efficient rates of germination in a changing climate when seeds are sown. In the context of the indoor germination of seeds for food, consumption, or processing purposes, a more efficient and sustainable process is desired. Therefore, novel techniques to facilitate seed germination are required. Pulsed electric fields (PEF) treatment of seeds results in the permeabilization of the cell membrane, allowing water to be taken up more quickly and triggering biochemical changes to the macromolecules in the seed during germination. Therefore, PEF could be a chemical-free approach to induce a stress response in seeds, leading to the production of secondary metabolites known to exert beneficial effects on human health. However, this application of PEF, though promising, requires further research to optimize its impact on the protein and bioactive compounds in germinating seeds.
ABSTRACT
Canned paua, Haliotis iris, is a premium New Zealand product that is exported to Asia. The objective of this research was to investigate the effects of ultrasound treatments on paua texture, microstructure and in vitro protein digestibility. Whole paua meat was ultrasound-treated (20 kHz, 464 ± 9 W) for 5 min in water (with or without subsequent soaking in water at 4 °C for 24 h) or ultrasound-treated in 1% actinidin enzyme solution. Post-treatment cooking of canned paua was done in a water retort at 116 °C for 30 min. All ultrasound-treated cooked paua yielded lower slice shear force values (SSFV) than untreated canned and cooked samples. The lowest SSFV was attained when ultrasound treatment in water was followed by soaking at 4 °C for 24 h. The increased tenderness of ultrasound-treated paua could be linked to disintegration of myofibers and formation of gaps between myofibers, as observed through histological analysis and transmission electron microscopy. Collagenous fragmentation was also observed, particularly in paua ultrasonicated in enzyme solution. Raw paua was found to be more digestible in terms of free amino N released during in vitro digestion than all cooked samples. However, cooked ultrasound pre-treated paua was more digestible than the control cooked sample.
