Characterizing physicochemical, nutritional and quality attributes of wholegrain Oryza sativa L. subjected to high intensity ultrasound-stimulated pre-germination

Impact of ultrasonication on the physicochemical, pasting, amino acid, mineral, phenolic, and sugar profile of germinated brown rice from various varieties

Germinated rice, recognized for its enhanced nutritional and functional properties, is a subject of increasing interest due to its potential health benefits. Ultrasonic low-frequency sound waves (40 kHz) treatment of seeds is a green technology that promises to enhance germination capacity of the grains and functional and biochemical properties through the stimulation of water-oxygen uptake and seed metabolism. Ultrasonication treatment (5, 10 and 15 min) significantly enhanced the protein and total dietary fibre content of (brown rice) BR from different varieties. Results showed that ultrasonication accelerated starch and phytic acid degradation and increased the reduced sugar content via activation of alpha-amylase. Moreover, the ultrasonically treated BR had higher levels of gamma-aminobutyric acid, essential amino acids and other bioactive compounds. Ultrasonicated germinated grain can be utilize further by food industry for making functional foods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-06039-4.

Ultrasound-assisted germination of red kidney beans: Enhancements in physicochemical and nutritional profiles

To improve the conventional germination process and improve the nutritional quality of red kidney beans, this study employed high-intensity ultrasound (HIU) supplemented with hydrogen peroxide as a pre-germination treatment. The results showed that the 350 W-10 min treatment yielded the highest germination rate (77.09%), with its sprout length 81.13% greater than that of the control group. The 350 W-10 min treatment increased total protein, soluble protein, and ash content, while simultaneously reducing the fat, starch, and soluble sugar content. The HIU treatment accelerated the accumulation of phenolic and flavonoid compounds, ascorbic acid, and γ-aminobutyric acid. The 350 W-10 min treatment also decreased the levels of phytic acid, trypsin inhibitor activity, and tannin by 42.71%, 65.58%, and 53.18%, respectively. Furthermore, ultrasonic cavitation enhanced antioxidative capacity and improved amino acid composition and protein digestibility. Consequently, HIU serves as a cost-efficient method to accelerate the germination process and enhance their nutritional composition.

Effect of ultrasonically stimulated potato germination during soaking on the physicochemical properties of starch and its use in edible films

The aim of this work was to investigate the effects of ultrasonic treatment during soaking of potatoes on the physicochemical properties of starches obtained after 16 weeks of germination. The ultrasonic treatment showed a direct correlation between sprout length and ultrasonic time. The protein content decreased from 0.63 to 0.38 % and the fat content decreased significantly from 0.31 to 0.01 % after germination. The amylose content changed depending on the ultrasonic treatment, and increased from 36.27 to 40.92 % after 16 weeks of germination, which was related to the amylopectin debranching and the duration of the ultrasonic treatment. X-ray diffraction showed that the nanocrystals with hexagonal structure were not affected by the germination and the duration of ultrasonic treatment. Scanning electron microscopy showed that the surface of the starch granules was not affected by the enzymatic treatment. The sprouted potato starch resulted in films with better tensile strength and lower water vapor permeability (WVP) compared to the native potato starch films. In addition, the films produced with ultrasound stimulated potato starch exhibited better properties (high strength and low permeability), which is desirable when it comes to controlling moisture exchange between a food product and the surrounding atmosphere.

Non-Targeted Metabolomics Analysis of γ-Aminobutyric Acid Enrichment in Germinated Maize Induced by Pulsed Light

Pulsed light is an emerging technique in plant physiology recognized for its ability to enhance germination and accumulate γ-aminobutyric acid in maize. Pulsed light involves exposing plants to brief, high-intensity bursts of light, which can enhance photosynthesis, improve growth, and increase resistance to environmental stresses. Despite its promising potential, the specific metabolic changes leading to γ-aminobutyric acid enrichment in maize induced by pulsed light are not fully understood. This study addresses this gap by quantifying key nutrients and γ-aminobutyric acid-related compounds during maize germination and investigating the underlying mechanisms using non-targeted metabolomics. Our findings indicate that pulsed light significantly promotes maize germination and accelerates the hydrolysis of proteins, sugars, and lipids. This acceleration is likely due to the activation of enzymes involved in these metabolic pathways. Additionally, pulsed light markedly increases the content of glutamic acid and the activity of glutamate decarboxylase, which are crucial for γ-aminobutyric acid synthesis. Moreover, pulsed light significantly reduces the activity of γ-aminobutyric transaminase, thereby inhibiting γ-aminobutyric acid decomposition and resulting in a substantial increase in γ-aminobutyric acid content, with a 27.20% increase observed in germinated maize following pulsed light treatment. Metabolomic analysis further revealed enrichment of metabolic pathways associated with γ-aminobutyric acid, including amino acid metabolism, carbohydrate metabolism, plant hormone signal transduction, energy metabolism, pyrimidine metabolism, and ABC transporters. In conclusion, pulsed light is a robust and efficient method for producing sprouted maize with a high γ-aminobutyric acid content. This technique provides a novel approach for developing sprouted cereal foods with enhanced nutritional profiles, leveraging the physiological benefits of γ-aminobutyric acid, which include stress alleviation and potential health benefits for humans.

Impact of germination pre-treatments on buckwheat and Quinoa: Mitigation of anti-nutrient content and enhancement of antioxidant properties

This study evaluated the effects of pre-germination treatments on the nutritional and anti-nutritional values of buckwheat and quinoa during germination. Pre-germination method was effective on the chemical composition and phenolic profile of buckwheat and quinoa samples (p < 0.05). During the germination, color changes were notable, particularly in the alkali-treated samples. The decrease in tannin content reached the highest rate in germinated buckwheat (83 %) and quinoa (20 %) by alkali treatment. The highest antioxidant and total phenolic content were measured in germinated pseudocereals treated by ultrasound. However, the lowest phytic acid content was determined after germination in the quinoa sample treated by ultrasound. Rutin was the major flavonoid in buckwheat while quercetin, galangin, ellagic, syringic, and p-coumaric acids were only synthesized after 72 h of germination. Catechin and epicatechin were decreased only in the alkali-treated buckwheat sample. Controlled germination processes can enhance the antioxidant activity and development of functional foods from whole grains.

Seed germination and seedling development assisted by ultrasound: gaps and future research directions

Since the early 1930s, when the first corn hybrids were grown commercially, innovations in the agriculture industry have had an unprecedent impact worldwide, helping to meet the demands for food of an exponentially growing population. In particular, seed technology research has contributed substantially to the improvement of crop performance over the years. Ultrasonic treatment of seeds is a green technology that promises to have an impact on the food industry, enhancing germination and seedling development in different species through the stimulation of water and oxygen uptake and seed metabolism. The increase in starch degradation has been associated with the stimulation of the α-amylases of the endosperm, but relatively few reports focus on how ultrasound affects seed germination at the biochemical and molecular levels. For instance, the picture is still unclear regarding the impact of ultrasound on transcriptional reprogramming in seeds. The purpose of this review is to assess the literature on ultrasound seed treatment accurately and critically, ultimately aiming to encourage new scientific and technological breakthroughs with a real impact on worldwide agricultural production while promoting sustainable practices on biological systems. © 2023 Society of Chemical Industry.

Enhancement of γ-Aminobutyric Acid and the Characteristics of Nutrition and Function in White Quinoa through Ultrasound Stress at the Pre-Germination Stage

The global production of quinoa has been increasing in recent years. In plant-based foods, ultrasound stress has received increasing attention, owing to its ability to enhance the production of primary and secondary metabolites. We studied the effects of ultrasonic stress at the pre-germination stage on the γ-aminobutyric acid (GABA) accumulation and characteristics of nutrition and function in quinoa. The results showed that ultrasonic conditions of 100 W for 4 min promoted an increase in GABA content by 9.15-fold, to 162.47 ± 6.69 mg/100 g·DW, compared to that of untreated quinoa, through promoting a 10.2% and 71.9% increase in the water absorption and glutamate decarboxylase activity of quinoa, respectively. Meanwhile, compared to untreated quinoa, ultrasonic stress at the pre-germination stage enhanced the total phenolic, total flavonoid, and total saponin contents of quinoa by 10.2%, 33.6%, and 90.7%, to 3.29 mg GA/g·DW, 104.0 mg RE/100 g·DW, and 7.13 mg/g, respectively, without decreasing its basic nutritional quality. Ultrasonic stress caused fissures on the surface of quinoa starch particles. Additionally, germination under ultrasonic stress increased the n3 polyunsaturated fatty acids by 14.4%. Furthermore, ultrasonic stress at the pre-germination stage promoted the scavenging of 2,2-diphenyl1-picrylhydrazyl radicals and inhibitions of α-amylase, α-glucosidase, and pancreatic lipase by 14.4%, 14.9%, 24.6%, and 20.0% in vitro, compared to untreated quinoa. The results indicated that the quinoa sprouted via ultrasonic stress could represent a promising method through which to develop nutritionally balanced whole grains rich in GABA, with hypoglycemic and hypolipidemic activities, which could provide theoretical support for the development of functional whole-grain foods based on quinoa.

Active compounds: A new direction for rice value addition

The development of rice active compounds is conducive to improving the added value of rice. This paper focused on the types and effects of active compounds in rice. Furthermore, it summarized the effect of rice storage and processing technology on rice active compounds. We conclude the following: Rice contains a large number of active compounds that are beneficial to humans. At present, the research on the action mechanism of rice active compounds on the human body is not deep enough, and the ability to deeply process rice is insufficient, greatly limiting the development of the rice active compound industry. To maximize the added value of rice, it is necessary to establish a dedicated preservation and processing technology system based on the physicochemical properties of the required active compounds. Additionally, attention should be paid to the development and application of composite technologies during the development of the rice active compound industry.

Recent developments in applications of physical fields for microbial decontamination and enhancing nutritional properties of germinated edible seeds and sprouts: a review

Germinated edible seeds and sprouts have attracted consumers because of their nutritional values and health benefits. To ensure the microbial safety of the seed and sprout, emerging processing methods involving physical fields (PFs), having the characteristics of high efficiency and environmental safety, are increasingly proposed as effective decontamination processing technologies. This review summarizes recent progress on the application of PFs to germinating edible seeds, including their impact on microbial decontamination and nutritional quality and the associated influencing mechanisms in germination. The effectiveness, application scope, and limitation of the various physical techniques, including ultrasound, microwave, radio frequency, infrared heating, irradiation, pulsed light, plasma, and high-pressure processing, are symmetrically reviewed. Good application potential for improving seed germination and sprout growth is also described for promoting the accumulation of bioactive compounds in sprouts, and subsequently enhancing the antioxidant capacity under favorable PFs processing conditions. Moreover, the challenges and future directions of PFs in the application to germinated edible seeds are finally proposed. This review also attempts to provide an in-depth understanding of the effects of PFs on microbial safety and changes in nutritional properties of germinating edible seeds and a theoretical reference for the future development of PFs in processing safe sprouted seeds.

Proposing Signaling Molecules as Key Optimization Targets for Intensifying the Phytochemical Biosynthesis Induced by Emerging Nonthermal Stress Pretreatments of Plant-Based Foods: A Focus on γ-Aminobutyric Acid

Emerging evidence has confirmed the role of emerging nonthermal stressors (e.g., electromagnetic fields, ultrasonication, plasma) in accumulating bioactive metabolites in plant-based food. However, the signal decoding mechanisms behind NonTt-driven phytochemical production remain unclear, hindering postharvest bioactive component intensification. This study aims to summarize the association between signaling molecules and bioactive secondary metabolite production under nonthermal conditions, demonstrating the feasibility of enhancing phytochemical accumulation through signaling molecule crosstalk manipulation. Nonthermal elicitors were found to be capable of inducing stress metabolisms and activating various signaling molecules, similar to conventional abiotic stress. A simplified pathway model for nonthermally induced γ-aminobutyric acid accumulation was proposed with reactive oxygen species and calcium signaling being versatile pathways responsive to nonthermal elicitors. Manipulating signal molecules/pathways under nonthermal conditions can intensify phytochemical biosynthesis. Further research is needed to integrate signaling molecule responses and metabolic network shifts in nonthermally stressed plant-based matrices, balancing quality modifications and intensification of food functionality potential.

Effects of High Intensity Ultrasound Stimulation on the Germination Performance of Caper Seeds

The caper bush has developed different mechanisms to survive in Mediterranean conditions, such as drought tolerance and seed dormancy. Many studies have been carried out to improve the germination of caper seeds, but ultrasound is one of the least studied methodologies in this species. This study aimed to analyze the effects of treatments with an ultrasonic probe processor on the imbibition and germination of caper seeds. After applying the ultrasound treatment using three output powers and three holding times, the seed coat's disruption level was determined, and the imbibition, viability and germination tests were carried out. Ultrasonication fastens the initial imbibition, but after 48 h of soaking, seed moisture does not present differences compared to non-sonicated seeds. It produces the scarification of the testa but does not affect the tegmen, so moistening occurs through the hilar region, as in control seeds. There is a significant linear and negative correlation between the germination of the seeds and the temperature reached during the sonication treatment, so that temperatures above 40 °C practically annulled the germination. The combination of 20 W and 60 s provided the greatest germination percentage, being the only treatment that statistically improves germination in relation to the control seeds. When the output power and/or holding time were higher, the temperature increased, and the germination percentage statistically decreased.

Combined ultrasound and germination treatment on the fine structure of highland barley starch

Highland barley is a grain crop grown in Tibet, China. This study investigated the structure of highland barley starch using ultrasound (40 kHz, 40 min, 165.5 W) and germination treatments (30℃ with 80% relative humidity). The macroscopic morphology and the barley's fine and molecular structure were evaluated. After sequential ultrasound pretreatment and germination, a significant difference in moisture content and surface roughness was noted between highland barley and the other groups. All test groups showed an increased particle size distribution range with increasing germination time. FTIR results also indicated that after sequential ultrasound pretreatment and germination, the absorption intensity of the intramolecular hydroxyl (-OH) group of starch increased, and hydrogen bonding was stronger compared to the untreated germinated sample. In addition, XRD analysis revealed that starch crystallinity increased following sequential ultrasound treatment and germination, but a-type of crystallinity remained after sonication. Further, the Mw of sequential ultrasound pretreatment and germination at any time is higher than that of sequential germination and ultrasound. As a result of sequential ultrasound pretreatment and germination, changes in the content of chain length of barley starch were consistent with germination alone. At the same time, the average degree of polymerisation (DP) fluctuated slightly. Lastly, the starch was modified during the sonication process, either prior to or following sonication. Pretreatment with ultrasound illustrated a more profound effect on barley starch than sequential germination and ultrasound treatment. In conclusion, these results indicate that sequential ultrasound pretreatment and germination improve the fine structure of highland barley starch.

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.

Ultrasonic treatment to enhance seed germination and vigour of wheat (Triticum durum) in association with γ-aminobutyric acid (GABA) shunt pathway

Treatments of wheat (Triticum durum L.) seeds with sonication or hydropriming may enhance seed germination and vigour in association with γ-aminobutyric acid (GABA). Therefore, the objective of this study is to examine the effect of sonication and hydropriming treatments on seed germination of wheat through the characterisation of seed germination performance, GABA shunt metabolite level (GABA, glutamate, and alanine), and the level of glutamate decarboxylase (GAD) mRNA transcription. Wheat seeds were exposed to three treatments for 0, 5, 10, 15, and 20min: (1) sonication with water; (2) sonication without water; and (3) hydropriming without sonication. Treated seeds were evaluated for germination percentage, mean time to germinate, germination rate index in the warm germination test, and seedling emergence and shoot length in the cold test. GABA shunt metabolites level (GABA, glutamate, and alanine), and the level of GAD mRNA transcription were measured for the seeds after treatments and for seedlings during germination and cold tests. Seeds treated with sonication or hydropriming treatments had a higher germination rate index (faster germination) in the standard germination test, and higher seedling emergence and shoot length in the cold test. Seeds treated with sonication or hydropriming treatments showed an enhancement in GABA shunt and their metabolites (alanine and glutamate), and GAD mRNA transcription level compared to untreated-control seeds. In conclusion, the sonication or hydropriming treatments significantly improved the germination performance of wheat and enhanced GABA metabolism to maintain the C:N metabolic balance, especially under cold stress.

The Alleviation of Metal Stress Nuisance for Plants—A Review of Promising Solutions in the Face of Environmental Challenges

Environmental changes are inevitable with time, but their intensification and diversification, occurring in the last several decades due to the combination of both natural and human-made causes, are really a matter of great apprehension. As a consequence, plants are exposed to a variety of abiotic stressors that contribute to their morpho-physiological, biochemical, and molecular alterations, which affects plant growth and development as well as the quality and productivity of crops. Thus, novel strategies are still being developed to meet the challenges of the modern world related to climate changes and natural ecosystem degradation. Innovative methods that have recently received special attention include eco-friendly, easily available, inexpensive, and, very often, plant-based methods. However, such approaches require better cognition and understanding of plant adaptations and acclimation mechanisms in response to adverse conditions. In this succinct review, we have highlighted defense mechanisms against external stimuli (mainly exposure to elevated levels of metal elements) which can be activated through permanent microevolutionary changes in metal-tolerant species or through exogenously applied priming agents that may ensure plant acclimation and thereby elevated stress resistance.

High Hydrostatic Pressure-Based Combination Strategies for Microbial Inactivation of Food Products: The Cases of Emerging Combination Patterns

The high demand for fresh-like characteristics of vegetables and fruits (V&F) boosts the industrial implementation of high hydrostatic pressure (HHP), due to its capability to simultaneously maintain original organoleptic characteristics and to achieve preservative effect of the food. However, there remains great challenges for assuring complete microbial inactivation only relying on individual HHP treatments, including pressure-resistant strains and regrowth of injured microbes during the storage process. Traditional HHP-assisted thermal processing may compromise the nutrition and functionalities due to accelerated chemical kinetics under high pressure conditions. This work summarizes the recent advances in HHP-based combination strategies for microbial safety, as exemplified by several emerging non-thermally combined patterns with high inactivation efficiencies. Considerations and requirements about future process design and development of HHP-based combination technologies are also given.

Effects of Microwave Treatment on Structure, Functional Properties and Antioxidant Activities of Germinated Tartary Buckwheat Protein

Tartary buckwheat protein (TBP) has promise as a potential source of novel natural nutrient plant protein ingredients. The modulating effects of microwave pretreatment at varying powers and times on the structure, functional properties, and antioxidant activities of germinated TBP were investigated. Compared with native germinated TBP, after microwave pretreatment, the content of free sulfhydryl groups in the germinated TBP increased, and the secondary structure changes showed a significant decrease in α-helix and an increase in random coil contents, and the intensity of the ultraviolet absorption peak increased (p < 0.05). In addition, microwave pretreatment significantly improved the solubility (24.37%), water-holding capacity (38.95%), emulsifying activity index (17.21%), emulsifying stability index (11.22%), foaming capacity (71.43%), and foaming stability (33.60%) of germinated TBP (p < 0.05), and the in vitro protein digestibility (5.56%) and antioxidant activities (DPPH (32.35%), ABTS (41.95%), and FRAP (41.46%)) of germinated TBP have also been improved. Among different treatment levels, a microwave level of 300 W/50 s gave the best results for the studied parameters. Specifically, microwave pretreatment could be a promising approach for modulating other germinated plant protein resources, as well as expanding the application of TBP.

Effect of Ultrasonic Induction on the Main Physiological and Biochemical Indicators and γ–Aminobutyric Acid Content of Maize during Germination

Research on the nutrient content of cereal grains during germination is becoming a hot topic; however, studies on germinated maize are still scarce. This study aimed to provide a technical reference and theoretical basis for the development of functional maize health foods and to expand the application of ultrasonic technology in the production of germinated grains. In this study, the germination rate of maize was used as the evaluation index, and the ultrasonic frequency, ultrasonic temperature, and induction time were selected as the influencing factors in orthogonal experiments to determine the optimal process parameters for ultrasonic induction of maize germination (ultrasonic frequency of 45 kHz, ultrasonic temperature of 30 °C, and ultrasonic induction time of 30 min). Based on this process, the effects of ultrasonic induction on the main physiological, biochemical, and γ–aminobutyric acid contents of maize during germination were investigated. The results showed that the respiration of the ultrasonic treated maize was significantly enhanced during germination, resulting in a 27% increase in sprout length, as well as a 4.03% higher dry matter consumption rate, and a 2.11% higher starch consumption rate. Furthermore, the reducing sugar content of germinated maize increased by 22.83%, soluble protein content increased by 22.52%, and γ–aminobutyric acid content increased by 30.55% after ultrasonic induction treatment. Throughout the germination process, the glutamate acid decarboxylase activity of the ultrasonically treated maize was higher than that of the control group, indicating that ultrasonication can promote maize germination, accelerate the germination process, and shorten the enrichment time of γ–aminobutyric acid in germinated maize. The results of this study can be applied to the production of γ–aminobutyric acid enrichment in germinated maize.

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.

Seed priming with non-ionizing physical agents: plant responses and underlying physiological mechanisms

Seed priming has long been explored as an effective value-added potential technique that results in improved germination, reduced seedling emergence time, shortened crop duration, increased stress tolerance and eventually increased higher grain production. However, the wider applicability of water or chemical-based conventional methods of seed priming is often restricted considering its deleterious effects on post-treatment storability or agricultural pollution due to the persistence of chemicals in plant systems or in the environment. In this context, the utilization of physical methods of seed priming for enhancing plant productivity has created a new horizon in the domain of seed technology. Being eco-friendly and cost-effective approaches, priming with extra-terrestrial or physical agents such as ionizing radiation such as X-rays and gamma rays and non-ionizing radiation such as ultrasonic wave, magnetic field, microwaves, and infrared light offers many advantages along with ensuring enhanced production over conventional methods. Ultraviolet radiations, bridging between ionizing and non-ionizing radiation, are important electromagnetic waves that would also be an effective priming agent. Non-ionizing radiation has certain biological advantages over ionizing radiation since it does not generate charged ions while passing through a subject, but has enough energy to cause biological effects. Extensive research works to study the effects of various non-ionizing physical priming methods are required before their wider exploitation in agriculture. With this background, this review aims to highlight the current understanding of non-ionizing physical methods of seed priming and its applicability to combat present-day challenges to achieve agro-ecological resilience.

The effects of ultrasonication on the phytochemicals, antioxidant, and polyphenol oxidase and peroxidase activities in coffee leaves

In the present study, we investigated the impacts of ultrasonic conditions on the phytochemical profiles, antioxidant activity, and polyphenol oxidase (PPO) and peroxidase (POD) activities in coffee leaves. Ultrasonic frequency, power, and time, pH, and incubation time affected PPO and POD differently, thus resulting in different ABTS scavenging capacity and phenolic content in coffee leaves. Triple-frequency (20/35/50 kHz) ultrasound significantly (P < 0.05) inhibited trigonelline, caffeine, mangiferin, rutin, chlorogenic acids, antioxidant activity, and PPO activity, while the single frequency of 35 kHz increased the phenolics compounds, which was associated with the lowest POD activity. Increasing the incubation time after ultrasonication gradually decreased phenolic compounds and antioxidant activities, however, POD activity followed a temporal pattern of first increase and then decrease. Our results showed that PPO and POD were temporally inactivated after ultrasonication, which leading to the continuous decrease of phenolics in coffee leaves.

An untargeted metabolomic insight into the high-pressure stress effect on the germination of wholegrain Oryza sativa L

High hydrostatic pressure (HHP) technique is used as a novel abiotic stress factor for efficiently enhancing the biosynthesis of selected bioactive phytochemicals in germinated wholegrain, but the information about HHP stress-induced metabolic changes remains rather limited. Thus, the current work employed an untargeted gas chromatography-mass spectrometry-based metabolomic approach combining with multivariate models to analyze the effect of mild HHP stress (30 MPa/5 min) on the overall metabolome shifts of wholegrain brown rice (WBR) during germination. Simultaneously, major phenolics in germinated WBR (GBR) were detected by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, to explore the potential relationship between HHP stress-induced rice metabolome alternations and the biotransformation of bioactive components. The results demonstrated that the influence of HHP stress on GBR metabolite profiles was defined by germination durations, as revealed by the differentiation of the stressed grains from the naturally germinated grains at different germination points according to principal component analysis. This was further confirmed by the results of orthogonal projections to latent structures discriminant analysis, in which the discriminating metabolites between naturally germinated and HHP-stressed grains varied across the germination process. The metabolite signatures differentiating natural and HHP-stressed germination included glycerol-3-phosphate, monosaccharides, gamma-aminobutyric acid, 2,3-butanediol, glyceryl-glycoside, amino acids and myo-inositol. Besides, HHP stress led to the increase in ribose, arabinitol, salicylic acid, azelaic acid and gamma-aminobutyric acid, as well as the reduced phenolic acids. These results demonstrated that HHP stress before germination matched with appropriate process parameters could be used as a promising technology to tailor metabolic features of germinated products, thus exerting targeted nutrition and health implications.

Impact of ultrasonic treatment on rice starch and grain functional properties: A review

As a green, nonthermal, and innovative technology, ultrasonication generates acoustic cavitation in an aqueous medium, developing physical forces that affect the starch chemistry and rice grain characteristics. This review describes the current information on the effect of ultrasonication on the morphological, textural, and physicochemical properties of rice starch and grain. In a biphasic system, ultrasonication introduced fissures and cracks, which facilitated higher uptake of water and altered the rice starch characteristics impacting textural properties. In wholegrain rice, ultrasonic treatment stimulated the production of health-related metabolites, facilitated the higher uptake of micronutrient fortificants, and enhanced the palatability by softening the rice texture. This review provides insights into the future direction on the utilization of ultrasonication for the applications towards the improvement of rice functional properties.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.

Ultrasound Treatment of Buckwheat Grains Impacts Important Functional Properties of Resulting Flour

The benefit of not containing the gluten complex protein also provides problems with the achievement of typical and proper texture, especially in bakery products. Ultrasound (US) treatment has been previously studied on buckwheat as assistance treatment facilitating the release of antioxidant compounds. However, there is no study regarding the changes occurring in US-treated buckwheat grains regarding the structure-creating capacity, like water absorption, gelling, and pasting. The aim of this study is to the impact of US-treatment of buckwheat grains at 1:10, 1:5, and 1:2.5 solid: liquid ratio (in water). The particle size distribution, water absorption index (WAI), water solubility index (WSI), swelling power (SP), pasting characteristics, color, soluble, insoluble and total polyphenols content (SPC, IPC, TPC) and antioxidant activity (DPPH) were assessed in resulting flours. US-treatment caused specific agglomeration, resulting in bigger particles for 1:5, and 1:2.5 ratio treated samples, while higher dilution (1:10) increased smaller particle size fractions. The WAI and SP were the highest for the1:5 solid: liquid ratio sample, and the same sample revealed the highest peak viscosity, breakdown, and setback values. The ultrasound treatment increased the WSI, which was positively correlated with insoluble polyphenols content. The soluble polyphenols content decreased, and insoluble polyphenols content increased in all ultrasound treated samples. The DPPH scavenging activity remaining in grain after US treatment was lowered compared to the control sample. The relocation of pigments resulted in a redness and yellowish increase in all treated samples, while lightness was also increased but was most pronounced for a 1:10 ratio treated sample. The results suggest that ultrasound treatment of grain can improve the essential functional properties of buckwheat flour.