Sono-hydro priming process (ultrasound modulated hydration): Modelling hydration kinetic during paddy germination

Ultrasound treatments improve germinability of soybean seeds: The key role of working frequency

In this paper, the effects of ultrasound with different frequency modes on the sprouting rate, sprouting vigor, metabolism-related enzyme activity and late nutrient accumulation in soybean were investigated, and the mechanism of dual-frequency ultrasound promoting bean sprout development was explored. The results showed that, compared with control, the sprouting time was shortened by 24 h after dual-frequency ultrasound treatment (20/60 kHz), and the longest shoot was 7.82 cm at 96 h. Meanwhile, ultrasonic treatment significantly enhanced the activities of protease, amylase, lipase and peroxidase (p < 0.05), particularly the phenylalanine ammonia-lyase increased by 20.50%, which not only accelerated the seed metabolism, but also led to the accumulation of phenolics (p < 0.05), as well as more potent antioxidant activity at later stages of sprouting. In addition, the seed coat exhibited remarkable cracks and holes after ultrasonication, resulting in accelerated water absorption. Moreover, the immobilized water in seeds increased significantly, which was beneficial to seed metabolism and later sprouting. These findings confirmed that dual-frequency ultrasound pretreatment has a great potential to be used for seed sprouting and promoting the accumulation of nutrients in bean sprouts by accelerating water absorption and increasing enzyme activity.

Enhancement of Polyphenols and Antioxidant Activity in Germinated Black Highland Barley by Ultrasonication

The aim of this study was to investigate the effect of ultrasonic stress germination (USG) on total phenolic contents (TPC), total flavonoid contents (TFC), the phenolic compositions, and antioxidant activities of black highland barley (BHB). The USG processing parameters, polyphenol profile, phenolic compositions, and antioxidant activities were explored after USG. Results showed that the optimal USG parameters were as follows: 350 W ultrasonic pretreatment power, 30 °C ultrasonication temperature, 25 min ultrasonication time, and 64 h germination time. Under these conditions, the total phenolic content (688.84 ± 5.30 mg/100 g) and total flavonoid content (59.23 ± 0.45 mg/100 g) of BHB were increased by 28.55% and 10.15%, respectively, compared to the untreated samples. In addition, the USG treatment could more effectively enrich bound phenolic acids and free flavonoids, among which the content of catechin was significantly increased by USG and was the main characteristic substance. Moreover, the USG treatment could improve the antioxidant activity and had a higher antioxidant potency composite index (APC index) (97.91%) of BHB. These results indicate that USG might be an effective method to enrich polyphenols and improve antioxidant activity in BHB.

Effect of ultrasound combined with exogenous GABA treatment on polyphenolic metabolites and antioxidant activity of mung bean during germination

Mung bean seeds were treated by a combination of ultrasound and γ-aminobutyric acid (GABA). Effect of these treatments on the free polyphenols content, antioxidant activity, and digestibility of mung bean sprouts was evaluated. Additionally, phenolic compounds were analyzed and identified using a metabolomics approach. The combined ultrasound and GABA treatments significantly enhanced the free polyphenols and flavonoids content (P < 0.05) of mung bean sprouts depending on sprouting duration. Besides, a positive correlation (P < 0.05) was found between the polyphenols content and in vitro antioxidant activity of mung bean sprouts. Moreover, a total number of 608 metabolites were detected, and 55 polyphenol compounds were identified, including flavonoids, isoflavones, phenols, and coumarins. Also, the KEGG metabolic pathway analysis revealed 10 metabolic pathways of phenols, including flavonoid, isoflavone, and phenylpropanoid biosynthesis. Powder of 48 h sprouted mung bean released polyphenols during simulated gastric digestion and possessed antioxidant activity.

Bioactive Nutrient Retention during Thermal-Assisted Hydration of Lupins

Lupin, an arid pulse, is gaining popularity as a super food due to its superior nutritional properties. However, it has not been considered for large scale thermal processing, e.g., canning. The present work evaluated the best time/temperature combination to hydrate lupins for canning with minimum losses of bioactive nutrients, pre-biotic fibre, and total solids during hydration. The two lupin species showed a sigmoidal hydration behaviour, which was adequately modelled by the Weibull distribution. The effective diffusivity, D_eff, increased from 7.41 × 10^-11 to 2.08 × 10^-10 m²/s for L. albus and 1.75 × 10^-10 to 1.02 × 10^-9 m²/s for L. angustifolius with increasing temperature, namely, from 25 °C to 85 °C. The lag phase decreased from 145 min to 56 min in L. albus and 61 min to 28 min in L. angustifolius. However, based on the effective hydration rate, reaching the equilibrium moisture, minimum loss of the solids, and prebiotic fibre and phytochemicals, 200 min hydration at 65 °C can be regarded as the optimum temperature of hydration. The findings are thus relevant for designing the hydration protocol to achieve the maximum equilibrium moisture content and yield with the minimum loss of solids (phytochemicals and prebiotic fibres) for L. albus and L. angustifolius.

Impact of low-frequency ultrasound technology on physical, chemical and technological properties of cereals and pseudocereals

Cereals (CE) and pseudocereals (PSCE) play a pivotal role in nourishing the human population. Low-frequency ultrasound (LFUS) modifies the structure of CE and PSCE macromolecules such as starch and proteins, often improving their technological, functional and bioactive properties. Hence, it is employed for enhancing the traditional processes utilized for the preparation of CE- and PSCE-based foods as well as for the upcycling of their by-products. We report recent advances in LFUS treatments for hydration, germination, extraction of bioactive compounds from by-products, and fortification of CEs and PSCE, including kinetic modelling and underlying action mechanisms. Meta-analyses of LFUS influence on compounds extraction and starch gelatinization are also presented. LFUS enhances hydration rate and time lag phase of CE and PSCE, essential for germination, extraction, fermentation and cooking. The germination is improved by increasing hydration, releasing promoters and eliminating inhibitors. Furthermore, LFUS boosts the extraction of phenolic compounds, polysaccharides and other food components; modifies starch structure, affecting pasting properties; causes partial denaturation of proteins, improving their interfacial properties and their peptides availability. Overall, LFUS has an outstanding potential to improve transformation processes and functionalities of CE and PSCE.

Improving soaking efficiency of soybeans through sweeping frequency ultrasound assisted by parameters optimization

Soybean soaking is important to the processing of bean products, however, restricted by the long soaking time. Herein, the soybean soaking was assisted by 60 kHz sweeping frequency ultrasound (SFU). Shortening mechanism of soaking time and physicochemical properties of soybeans were analyzed. Results showed that soaking temperature of 37 °C, ultrasonic power of 60% (144 W), and soaking time of 214 min were optimum SFU-assisted parameters. The soaking time was reduced by 45.13%, and soluble protein content increased by 14.27% after SFU. Based on analysis of acoustic signals, the maximum voltage amplitude of SFU increased with the increment of oscillation periods of cavitation bubbles, which enlarged the intercellular space and size of soybean, and cell membrane permeability was enhanced by 4.37%. Unpleasant beany flavor compounds were reduced by 16.37%-47.6%. Therefore, SFU could significantly improve the soaking efficiency of soybeans and provide a theoretical basis for the processing enterprises of soybean products.

Effect of ultrasonic pre-treatment on Ara h 1 in peanut sprouts

Ara h 1 is the most abundant sensitizing protein in peanuts; it has high thermal stability and is difficult to degrade. The peanut sprout is a high-quality, natural food that has various beneficial effects and lower allergenicity than peanut seeds. In this study, ultrasonication (US) of peanut sprouts was used to alter their Ara h 1 content. We determined that the optimal parameters for the US process were 35 °C temperature, 30 min duration, 240 W power, and 100 kHz frequency. After 5 days of germination, the protease activity of the control (blank) group increased to 262.39 ± 0.10 U, whereas that of the US group increased to 290.1 ± 0.25 U. We also investigated the effects of US on Ara h 1 protein composition, structure, and related gene expression during germination. ELISA results showed that after 5 days of germination, Ara h 1 content in the blank group decreased from 20.63 ± 0.31 ppm to 3.35 ± 0.42 ppm, whereas in the US group, they decreased to below the detection limit. SDS-PAGE bands between 50 and 70 kDa from peanut sprout extracts gradually became lighter in both groups. The band almost disappeared at day 5 of germination in the US group, indicating that US reduced the Ara h 1 content of peanut sprouts, consistent with the ELISA results. The expression of the Ara h 1 gene in peanut seeds was 173.92 ± 26.37. In the BK control group, it decreased to 0.49 ± 0.17 on the fourth day and increased slightly to 0.75 ± 0.09 on the fifth day. In the US group, it decreased to 1.37 ± 0.28 on the first day, dropped sharply to 0.00 on the third day, and increased slightly to 0.04 ± 0.01 on the fourth and fifth days. Protein structure results showed that the α-helix structure of Ara h 1 decreased after US, whereas the content of β-fold structures increased. The surface hydrophobicity decreased, and the secondary and tertiary structures of Ara h 1 were loose.