Ultrasound Pretreatment Research Articles

Techno-functional, physicochemical and thermal characteristics of black chickpeas aquafaba under ultrasound pre-processing

Aquafaba is the liquid that remains from the cooking of beans in the canning industry, generally discarded as wastewater. This research aimed to optimize ultrasound pretreatment to enhance this by-product and introduce it as a high-added value product (known as liquid gold) in the food industry. The results showed that with the increase in the sonication time and amplitude, the extraction efficiency, soluble protein content, the density, and dry matter content of black chickpeas aquafaba increased significantly (p<0.05). The results also demonstrated that foaming ability (in short ultrasonication times) and foam stability significantly increased with higher amplitude. The results of numerical optimization showed that ultrasound pre-treatment for 30 minutes with an amplitude of 72% on black chickpeas before the cooking process created the best conditions for aquafaba extraction. Under these optimized conditions, the results yielded the highest values so that extraction efficiency, protein content, density, dry matter, foaming ability, and foam stability were 212.07%, 3546.7 mg/kg, 1.038 g/mL, 4.76%, 243.57%, and 44.50% respectively. Thermogravimetric and FT-IR analysis showed that the pre-sonication process not only makes aquafaba thermally stable, but also does not cause any structural changes in its chemical components. According to the favorable physicochemical characteristics of aquafaba, this product can benefit the food industry. It can be a material with high added value, profitable for the canning industry.

Preparation and application of glucono-δ-lactone-induced gel of TGase cross-linked black bean protein isolate-whey protein isolate: Effect of ultrasound pretreatment

Preparation and application of glucono-δ-lactone-induced gel of TGase cross-linked black bean protein isolate-whey protein isolate: Effect of ultrasound pretreatment

Multi-frequency power ultrasound (MFPU) pretreatment of crayfish (Procambarus clarkii): Effect on the enzymatic hydrolysis process and subsequent Maillard reaction

Crayfish, as a new consumer trend, has become one of the most popular freshwater aquatic foods in China, and its processed product output has been increasing year by year. In this study, the effect of multi-frequency power ultrasound (MFPU) pretreatment in various working modes including mono-, dual- and tri-frequency on the enzymatic hydrolysis and Maillard reaction of crayfish was investigated. Additionally, the underlying mechanism was also explored. Results showed that the degree of hydrolysis (DH) of crayfish was 23.89 %, while it increased to 40.78 % after MFPU pretreatment at 20/40 kHz dual-frequency, indicating that MFPU pretreatment significantly (p < 0.05) enhanced the enzymatic hydrolysis of crayfish. The crayfish protein after MFPU pretreatment exhibited a decrease in α-helix and increase in β-fold content, and the occurrence in the unfolding of the protein structure and alteration of tertiary structure. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, the MFPU pretreatment resulted in the fragmentation of crayfish protein. During the analyses of subsequent Maillard reaction, the composition and quantity of volatiles detected by the electronic nose and GC–MS indicated that MFPU pretreatment enhanced flavor of the Maillard reaction products. In conclusion, MFPU pretreatment is a promising technology for improving the degree of hydrolysis of crayfish protein and enhancing the flavor of Maillard reaction products.

A Review of the Technological Aspects and Process Optimization of Bioethanol Production From Corn Stover Biomass: Pretreatment Process, Hydrolysis, Fermentation, Purification Process, and Future Perspective

ABSTRACTBioethanol, a sustainable energy solution derived from renewable biomass, has gained prominence, with corn stover emerging as a substantial biomass resource in Indonesia. Corn stover, a corn residue, is one of the top three agricultural wastes worldwide and is abundantly available. However, a significant portion of corn stover is burned in fields rather than utilized for bioethanol production, whereas it has potential as a bioethanol feedstock. As the world strives to realize sustainable and environmentally friendly energy security, bioethanol production from corn stover can be one of the solutions to be developed. Nonetheless, the current immaturity of bioethanol production technology is one of the causes of large‐scale production failure. The present paper comprehensively reviews the technological aspects and process optimization of bioethanol production using corn stover as a feedstock comprising pretreatment, hydrolysis, fermentation, and bioethanol purification processes. According to our critical review, ammonia fiber expansion (AFEX) pretreatment is the most effective conventional pretreatment, with glucose yield up to 90%. Moreover, ultrasound appears to be the most viable option for nonconventional pretreatment of corn stover for producing bioethanol. However, combining ultrasound pretreatment and dilute aqueous ammonia produced 80.6% sugar output. Furthermore, enzymatic hydrolysis emerges as the most effective saccharification, yielding up to 81.39%. Moreover, the fermentation process of corn stover with the saccharification and co‐fermentation (SScF) method and the process optimization with response surface methodology (RSM) could produce bioethanol with a concentration of up to 59.8 g/L and 92.07% ethanol yield, respectively. This review also reveals that pervaporation for the purification process is the best choice for producing bioethanol with high purity up to &gt; 99%. In addition, this method could reduce the energy used by 6.6% lower, 24.2% lower carbon footprint, and have the lowest total capital and production costs compared to conventional molecular sieves and extractive distillation. We believe this review article can provide a reference for selecting the best bioethanol production process from corn stover for further research.

Debittering Process of Lupin (Lupinus albus l.) by Ultrasound Pre-treatment

Bu çalışma, acı baklanın (Lupinus albus L.) acılığı giderme sürecinde bir ön işlem yöntemi olarak ultrasonun etkinliğini araştırarak, genel kalitesini ve besin profilini iyileştirmeyi amaçlamaktadır. Acı bakla tohumları protein ve diğer temel besin maddeleri bakımından bol miktarda bulunur, ancak başta acı bakla ve lupinidin olmak üzere acı alkaloidler içerirler ve bu da bunların gıda ve yem olarak kullanılmasında zorluklar yaratır. Geleneksel acılık giderme yöntemleri, zaman alıcı olan ve besin kayıplarına yol açabilen suya batırmayı içerir. Ultrason, besin bütünlüğünden ödün vermeden acılık giderme sürecini hızlandırma kabiliyeti nedeniyle umut verici bir alternatif olarak ortaya çıkıyor. Bu araştırmada, acılık giderme verimliliğini optimize etmek için acı bakla tohumlarına çeşitli koşullar altında ultrason ön işlemi uygulandı. Ultrason gücü, işlem sıcaklığı ve süresi gibi parametreler, alkaloitlerin uzaklaştırılması ve besin içeriğinin korunması üzerindeki etkilerini belirlemek için sistematik olarak değerlendirildi. Ön işleme tabi tutulmuş Lupin numuneleri daha sonra alkaloit konsantrasyonları, protein içeriği ve diğer besin özelliklerindeki değişiklikler açısından analiz edildi. Uygulanan ultrason destekli ekstraksiyon yöntemi yeni bir bakış açısı getirmiş ve ısıtma işlemi ultrasonla uyarlanarak acılık giderme işlemi daha kısa sürede gerçekleştirilmiştir. Ön sonuçlar, acı bakla tohumlarındaki acılık seviyelerini ve alkaloid konsantrasyonlarını azaltmada ultrason ön işleminin etkinliğini göstermektedir. Üstelik süreç, Lupin'de bulunan temel besin maddelerini korur ve böylece insan tüketimi ve hayvan yemi için değerli bir protein ve diğer besin kaynağı olma potansiyelini artırır. Bu çalışma Lupin için sürdürülebilir ve verimli ön arıtma yöntemlerinin geliştirilmesine katkıda bulunarak gıda, yem ve çeşitli endüstriyel uygulamalarda daha geniş kullanımının yollarını açıyor.

The Application of Ultrasound Pre-Treatment in Low-Temperature Synthesis of Zinc Oxide Nanorods

Zinc oxide, due to its unique physicochemical properties, including dual piezoelectric and semiconductive ones, demonstrates a high application potential in various fields, with a particular focus on nanotechnology. Among ZnO nanoforms, nanorods are gaining particular interest. Due to their ability to efficiently transport charge carriers and photoelectric properties, they demonstrate significant potential in energy storage and conversion, as well as photovoltaics. They can be prepared via various methods; however, most of them require large energy inputs, long reaction times, or high-cost equipment. Hence, new methods of ZnO nanorod fabrication are currently being sought out. In this paper, an ultrasound-supported synthesis of ZnO nanorods with zinc acetate as a zinc precursor has been described. The fabrication of nanorods included the treatment of the precursor solution with ultrasounds, wherein various sonication times were employed to verify the impact of the sonication process on the effectiveness of ZnO nanorod synthesis and the sizes of the obtained nanostructures. The morphology of the obtained ZnO nanorods was imaged via a scanning electron microscope (SEM) analysis, while the particle size distribution within the precursor suspensions was determined by means of dynamic light scattering (DLS). Additionally, the dynamic viscosity of precursor suspensions was also verified. It was demonstrated that ultrasounds positively affect ZnO nanorod synthesis, yielding longer nanostructures through even reactant distribution. Longer nanorods were obtained as a result of short sonication (1–3 min), wherein prolonged treatment with ultrasounds (4–5 min) resulted in obtaining shorter nanorods. Importantly, the application of ultrasounds increased particle homogeneity within the precursor suspension by disintegrating particle agglomerates. Moreover, it was demonstrated that ultrasonic treatment reduces the dynamic viscosity of precursor suspension, facilitating faster particle diffusion and promoting a more uniform growth of longer ZnO nanorods. Hence, it can be concluded that ultrasounds constitute a promising solution in obtaining homogeneous ZnO nanorods, which is in line with the principles of green chemistry.

Effect of enzymatic hydrolysis and ultrasound pretreatment on allergenicity, functional properties and bioactivity of whey protein isolates

Whey protein isolate (WPI) is an important food ingredient and a major allergen in food. Enzymatic hydrolysis is an important method for WPI modification, but there is limited information on the effect of ultrasound pretreatment on WPI hydrolysates (WPH). The aim of this study was to analyze the effect of enzymatic hydrolysis and ultrasound pretreatment on the allergenicity, functional properties and bioactivity of WPH by multispectroscopy and peptidomics combined with bioinformatics. The results showed that ultrasound pretreatment contributed to the production of WPH with low allergenicity (IgE binding capacity is 55.59%) and good functional properties (emulsifying activity index is 27.02%, foaming characteristic is 50.00%) and bioactivity (total antioxidant capacity is 65.94%). This was attributed to the synergistic hydrolysis of WPI by endopeptidases and exopeptidases, and ultrasound pretreatment that altered the accessibility of WPI to proteases and the peptide profiles and main proteins of WPH, affecting the changes in their spatial and primary structure. This research will advance the application of WPI in hypoallergenic foods.

A comparative study of pulsed electric field, ultrasound, milling and soaking as pre-treatments for assistance in the extraction of polyphenols from willow bark (Salix alba)

White willow (Salix alba) has a long history of use as an herbal remedy for treating common pain and inflammation. Pre-treatment is a crucial step that assists the subsequent extraction process and may affect the extraction efficiency of polyphenols from plant materials. The objective of this work was to study the impact of pre-treatment methods on the hot water extraction of polyphenols from willow bark. Pulsed electric field (PEF) and ultrasound (US) pre-treatments were compared to commonly used pre-treatment methods, milling and soaking. All pre-treatments significantly increased the total phenolic content (TPC) and antioxidant activity (p < 0.05) in willow extracts. At a similar energy level, PEF with 400 pulses yielded a higher TPC (44.33mg GAE/g d.w.) and antioxidant activity (DPPH of 74.58mg AAE/g and FRAP of 186.41mmol TE/g) than US pre-treated samples, but a small increase in ultrasonic energy resulted in the highest TPC (46.20mg GAE/g d.w.) and antioxidant activity (DPPH of 76.18mg AAE/g and FRAP of 220.20mmol TE/g) of all the pre-treatments. Compared with PEF and US, milling (42.69mg GAE/g d.w.) and soaking (40.29mg GAE/g d.w.) were less effective in recovering polyphenols but they were comparable with PEF and US when employed at low energy levels. Overall results indicate emerging technologies PEF and US can be alternatives to milling to enhance the extractability of polyphenols and to reduce energy consumption. The obtained willow extracts were a rich source of polyphenols that could be used for food and pharmaceutical applications.

Effect of ultrasound and enzymatic pre-treatments on the profile of bioactive peptides of beef liver hydrolysates

The use of meat by-products as a potential source of protein hydrolysates rich in bioactive peptides is of growing interest to valorise these products and improve their sustainable use. This study aimed to evaluate the effect of different pre-treatments (hydrolysis with pepsin, ultrasounds, and ultrasounds-assisted pepsin hydrolysis) on the peptide profile and bioactivity of beef liver hydrolysed with flavourzyme. The pre-treatments with pepsin increased the degree of hydrolysis and generation of free amino acids in the liver hydrolysates, whereas the subsequent hydrolysis with flavourzyme influenced the molecular weight distribution of the peptides. Samples pre-treated with pepsin and ultrasounds-assisted pepsin hydrolysates showed the highest values of antioxidant and inhibitory activity of ACE-I, ECE-I, DPP-IV, and neprilysin enzymes, and therefore these hydrolysates were characterised to obtain the bioactive peptide profiles. A total of 995 peptides were identified by tandem mass spectrometry in the most active fractions separated by reversed-phase liquid chromatography, and 20 of them were predicted as potentially responsible for the observed bioactivities and subsequently characterised by in silico tools. These results evidenced the potential of hydrolysis pre-treatments with pepsin and ultrasounds-assisted pepsin to obtain beef liver hydrolysates rich in bioactive peptides that could exert multifunctional bioactivities such as antioxidant, antihypertensive, and antidiabetic, while giving added value to this meat by-product.

Effect of ultrasound immersion pretreatment combined magnetic field assisted freezing on the quality of frozen blueberries

This study investigated the effect of ultrasound combined with static magnetic field freezing on the freezing process and quality changes of blueberries. The aim is to provide a reference for the study of magnetic fields in food. The freezing parameters, quality, and microstructural structure were examined. The results showed that the effect of ultrasound-assisted static magnetic field freezing (U-MF) was better, which significantly shorted the freezing time of the sample. In comparison to −20 °C control frozen (CF), the degree of supercooling increased by 50.08%, freezing time shorted by 16.36%, drip loss decreased by 28.28%, respectively, and the water distribution state was closer to that of fresh fruits. Microstructural analysis indicated that the sample structure of U-MF treated blueberries was better approximated by the fresh sample. Moreover, overall sensory scores for blueberries showed that U-MF treated blueberries presented positive sensory evaluation. In conclusion, ultrasound and static magnetic field play a synergistic effect in assisting freezing, and the combined effect is better than that of ultrasound or static magnetic field alone.

Ultrasound and high-speed shear pretreatments of walnut meal protein: Structural and functional characterization and mechanistic investigation

The study aims to investigate the effect of the addition of ultrasound (US) with high-speed shear (HSS) at the extraction stage on the yield, physicochemical, structural, and functional properties of walnut meal protein (WMP). Compared with the conventional alkaline soluble acid precipitation method, the WMP yields after US and HSS pretreatments were increased by 1.11 and 1.21 times, respectively. Protein samples treated with the US showed increased surface hydrophobicity, a more uniform distribution of particle sizes, and greater contact angles. SDS-PAGE results showed that the protein had broken peptide bonds at higher molecular weights. The proteins' free sulfhydryl groups and fluorescence intensity have both increased as a result of the two pretreatment approaches, indicating a substantial alteration in the proteins' tertiary structure. Dynamic light scattering and SEM findings revealed that the US and HSS treatments improved the protein water solubility and emulsion stability by reducing the aggregate particle size and homogenizing the protein dispersion system. These results indicate that US and HSS pretreatment can effectively solubilize WMP polymers and enhance the structural function of the protein. This provides a theoretical basis for the application of WMP in food processing and offers a suitable technology for improving protein utilization.

Effect of ultrasound pre-treatment on ultrafiltration performance in obtaining phenolic compounds from wine production wastes

Effect of ultrasound pre-treatment on ultrafiltration performance in obtaining phenolic compounds from wine production wastes

Effects of ultrasound blanching followed by hot air-coupled microwave drying on the quality of perilla leaves

To improve the drying efficiency and quality of dried perilla leaves, this work investigated the impact of ultrasound and blanching (UB) pretreatment followed by hot air coupled microwave drying (MHD) on the drying kinetics, activation energy, color difference and microstructure of perilla leaves. The effects of 2 UB duration (1 min, 3 min) and drying temperature (50, 60, 70 °C) on the chlorophyll, flavonoid and volatile content of perilla leaves were also evaluated. The results revealed that UB pretreatment increased the drying rate, improved the effective moisture diffusivity and reduced the activation energy. It was found that drying at 70 °C without UB pretreatment had the lowest ΔE (14.68) and highest chlorophyll (2.38 mg/g), whereas UB pretreatment could retain a greater content of flavonoids (0.116 mg/g) at 50 °C for 1 min and preserve better odor characteristics. Taken together, these findings suggest that UB pretreatment is an alternative method for maintaining good quality for the MHD of perilla leaves.

Effect of ultrasound pretreatment combined with different drying methods on the quality and bioactive compounds of broccoli stems

SummaryThe effects of ultrasound (US) pretreatment combined with drying process on storage quality maintenance and bioactive compound accumulation of broccoli stems were investigated. Results indicated that US pretreatment (λ = 8.5 mm) delayed the decline of L* value and ascorbic acid content but inhibited the increase of a* and b* values, browning index, and microbial counts of fresh‐cut broccoli stems. Furthermore, the US application enhanced total phenolics content by activating phenylalanine ammonia‐lyase, cinnamate‐4‐hydroxylase, and 4‐coumarate‐CoA ligase in phenylpropane metabolism. Meanwhile, it also promoted γ‐aminobutyric acid (GABA) accumulation by upregulating activities of diamine oxidase, polyamine oxidase, and aminoaldehyde dehydrogenase in GABA shunt and polyamine degradation pathway, respectively, which in turn, accelerated the biosynthesis of GABA from polyamines and glutamate. In addition, compared with other three drying methods, the combined vacuum freeze drying (VFD) could further retain the sensory attributes and bioactive compounds to a maximum extent in dehydrated broccoli stems. Hence, current findings illustrated that US pretreatment combined with VFD process is beneficial for commercial quality maintenance and nutritional value enhancement, thus providing new perspectives on the comprehensive utilisation of broccoli stems.

Impact of Ultrasound Pre-Treatment on the Drying Kinetics and Quality of Chicken Breast-A Comparative Study of Convective and Freeze-Drying Methods.

Fresh meat has a limited shelf life and is prone to spoilage. Drying serves as a common method for food preservation. Non-thermal techniques such as ultrasound treatment (US) can positively affect the drying processes and alter the final product. The study aimed to evaluate the impact of US pre-treatment on the hot air (HA) and freeze-drying (FD) of chicken breast meat and the quality of the dried products. US pre-treatment had a varied impact depending on the drying method used. The contact US method extended the HA drying time (about 50%) but improved water removal during FD (about 30%) compared to the untreated samples. Both methods resulted in low water content (<8.3%) and low water activity (<0.44). While rehydration properties (RR) and hygroscopicity (H) were not significantly affected by US pre-treatment in HA drying (about 1.35% and about 1.1, respectively), FD noticed differences due to shrinkage and porosity variations (RR: 2.4-3.2%, H: 1.19-1.25). The HA-dried samples exhibited notably greater tissue shrinkage and a darker surface color than the FD meat. Ultrasonic processing holds substantial potential in creating dried meat products with tailored characteristics. Hence, meticulous consideration of processing methods and parameters is of utmost importance.

Integration of ultrasound and microwave pretreatments with solid-state fermentation enhances the release of sugars, organic acids, and phenolic compounds in wheat bran

Wheat bran (WB), a byproduct of milling, is rich in bioactive compounds with significant health benefits. This study aimed to enhance the release of phenolic compounds, sugars, and organic acids from WB by integrating ultrasound (UsP) and microwave (MWP) pretreatments with solid-state fermentation (SSF). UsP and MWP disrupted WB cell walls, followed by SSF with Aspergillus niger. UsP increased total phenolic content by 21.30 % on day 1 of SSF. UsP and MWP boosted the availability of bound phenolic compounds like vanillic acid and dihydroxybenzoic acid. Both pretreatments enhanced antioxidant activity compared to untreated fermented WB, with peak activity on day 5 of fermentation at 1411 ± 5.156 μM Trolox/100 g DW for UsP WB and 291.6 ± 1.092 μM Trolox/100 g DW for MWP WB. This integrated approach improved the extraction efficiency of fermentable monosaccharides, particularly glucose and xylose, offering a sustainable bioprocessing strategy for WB valorization and supporting the circular bioeconomy.

Determining the impact of pre-pressing pretreatments applied to sugarcane on the aroma compounds and quality characteristics of sugarcane juice.

The study examined the effects of three pretreatments, blanching (5, 10, and 30min), ultrasound (15, 20, and 30min), and steam blanching (10, 20, and 30min) on sugarcane, assessing their impact on sugarcane juice quality parameters and aroma compounds. The control had the highest soluble solid content, while the ultrasound-15min (US-15min)-treated sample had the lowest, affecting pH, total acidity, and color values significantly. Color analysis showed lower L* values and less greenish tones in treated samples. The implemented pretreatments effectively reduce the browning index, with the US-20min treatment showing the most significant reduction compared to the control sample. All pretreatments deactivated polyphenol oxidase. Carbon isotope analysis yielded significant results. Principal component analysis and hierarchical clustering linked 1,1-diphenyl-2-picrylhydrazyl (DPPH) with 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 5-hydroxymethyl furfural (HMF) with total phenolic content. The study also highlights significant variations in aroma compound profiles among pretreated sugarcane juice samples, with blanching for 10 min showing notable increases in specific compounds like 2-heptanone and nonanol. Hierarchical clustering showed similarities between blanching-30min and US-30min, contrasting with the control. Blanching-10min had a positive impact on sugarcane juice quality. In conclusion, the study emphasized how pretreatments affect physicochemical properties and aroma compounds in sugarcane juice. PRACTICAL APPLICATION: The research findings suggest that blanching and ultrasound pretreatments can be used by the food industry to improve sugarcane juice quality by reducing browning, enhancing color, and altering aroma profiles. These pretreatments could extend the shelf life and appeal of sugarcane juice, making it more attractive to consumers while maintaining its nutritional properties.

Impact of Pretreatment With Acid and Ultrasound on the Production and Characteristics of Goat Skin Gelatin

Goat skin is a potential raw material source for gelatin production using acid-ultrasound pretreatment. The objective of this study was to investigate the use of ultrasound in combination with acid pretreatment for the preparation of goat skin gelatin. Gelatin was extracted from goat skin using different pretreatments: acetic acid (T1), acetic acid followed by ultrasound (20 kHz and 750 W) (T2), and without pretreatment (T0). The results showed that the combination of acetic acid and ultrasound pretreatment significantly impacted the quality of the resulting gelatin. The study results showed an increase in yield (9.24 to 25.48%), hydroxyproline content (102.07 to 231.31 mg/g), gel strength (4.76 to 197.62 g), viscosity (6.80 to 48.00 cP), melting point (32.47 to 35.85 oC), EAI (18.24 to 23.58 m2/g), and ESI (24.90 to 62.63 min). However, there was a decrease in pH, the value of color L*, and turbidity. The SDS-PAGE patterns showed differences in molecular weight distribution due to variations in pretreatment. All gelatin samples exhibited α1 and α2 chains as the predominant components. Interestingly, the ultrasound effect highlighted the β-chain more boldly compared to other pretreatments. FTIR spectroscopy analysis shows changes in molecular interactions due to acetic acid pretreatment followed by ultrasound, which results in shifts in the Amide A, Amide B, Amide I, Amide II, and Amide III groups. Ultrasonic treatment caused more dense and disturbed structures in the sample. Therefore, the combination of acetic acid and ultrasound pretreatment yielded the superior properties of goat skin gelatin.

Effects of combined ultrasound and calcium ion pretreatments on polyphenols during mung bean germination: Exploring underlying mechanisms

Mung beans were pretreated with a combination of ultrasonic and calcium ion to enhance the polyphenol content and antioxidant capacity during germination. Changes in polyphenol content and antioxidant capacity during germination, along with underlying mechanisms, were investigated. Both single ultrasound and combined ultrasound-Ca2+ pretreatments significantly increased the polyphenol content and enhanced the antioxidant capacity (p < 0.05) of mung beans depending on germination period. Among 74 polyphenolic metabolites identified in germinated mung beans, 50 were differential. Notably, 23 of these metabolites showed a significant positive correlation with antioxidant activity. Ultrasound pretreatment promoted flavonoid biosynthesis, whereas ultrasound-Ca2+ pretreatment favored the tyrosine synthesis pathway. Polyphenol composition and accumulation changes were mainly influenced by metabolic pathways like flavonoid, isoflavonoid, anthocyanin, and flavone/flavonol biosynthesis. The results suggest that ultrasound alone or combined with calcium ion pretreatments effectively enhance mung bean polyphenol content and antioxidant capacity during germination.

Drying kinetics of camellia oleifera seeds under hot air drying with ultrasonic pretreatment

Camellia oleifera seeds with high moisture content are prone to decay, leading to oil rancidity and seriously affecting subsequent processing and tea oil quality. Thus, an efficient drying method is needed. Hot air drying with ultrasonic pretreatment is a potential drying method for camellia oleifera seeds. In this paper, the effects of key parameters such as ultrasound power, ultrasound pretreatment time, and hot air drying temperature on the moisture ratio of camellia oleifera seeds, as well as the changes in microstructure of both seed shell and seed kernel, and the main quality parameters such as peroxide value and acid value of tea oil were explored. Results showed that the shorter the ultrasound pretreatment time, the greater the ultrasound power, the higher the temperature, the faster the drying rate, and the shorter the drying time. The drying time and specific energy consumption was reduced by up to 26.7 % and 16.8 % with the ultrasonic pretreatment, respectively. The optimal ultrasonic pretreatment time is 2 min, and the ultrasonic power is 300 W. A Genetic Algorithm Optimized Backpropagation Artificial Neural Network (GA-BP-ANN) drying model was proposed to predict the changes in moisture ratio during the drying process of camellia oleifera seeds to provide guidance for the development of intelligent drying system. The experimental results showed that the proposed drying model had a good predictive performance, with an RMSE of 0.0076969 and an R2 of 99.909 %, which can accurately estimate the effect of ultrasonic pretreatment on hot air drying. The research results of this study are expected to reduce post-harvest losses of camellia oleifera fruits and provide theoretical support for the development of drying systems of camellia oleifera seeds and similar agricultural products.