Search

Moderately processed surimi products exhibit better nutrient retention and enhanced gels, and the great potential of microwaves application and changes in the way of chopping meat has been reported by previous research. In this study, a systematic analysis of the novel surimi product was made to explore the heat and mass transfer characteristics. A porous media model combining electromagnetic heat and hygroscopic expansion was developed to evaluate this process, and its accuracy has been verified experimentally. It was found that the dielectric characterization of multiphase mixture system has great influence on the results, the complex refractive index mixture equation was used due to its lowest root-mean-square error value. In addition, the effect of moderate processing on microwave heating was examined in terms of porosity changes. However, nonuniform temperature distributions were found in the higher porous samples, especially when the porosity is greater than 0.81. Moreover, the developed model was coupled with the evaluation for gel properties and the results showed the significant effect of moderate crushing on the gel quality during the microwave heating process.

Fei Wu,1– 3,* Jie Chen,4,* Kang Yao,1 Daming Fan,5 Minglei Wang,2 Yongjun Liu,1 Shouhu Xin,1 Zeqiang Sun,1 Shun Li,1 Yang Sun,6 Qingyong Liu1 1Department of Urology, the First Affiliated Hospital of Shandong First Medical University, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250014, People’s Republic of China; 2Shandong Provincial Key Laboratory of Radiation Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250117, People’s Republic of China; 3Department of Urology, Shandong Provincial Hospital, Shandong First Medical University, Jinan, 250021, People’s Republic of China; 4Department of Urology, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250013, People’s Republic of China; 5Department of Pathology, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250013, People’s Republic of China; 6Department of Dermatology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250012, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yang Sun; Qingyong Liu, Email sunyang@qiluhospital.com; liuqingyong@sdhospital.com.cnIntroduction: A primary impediment to the efficacy of immune checkpoint inhibitors is the lack of biomarkers for therapeutic responses and prognosis. Although patients with clear cell renal cell carcinoma (ccRCC) could be precisely selected for targeted therapy based on somatic mutations, it remains controversial to choose the suitable patients with a high response rate to immune checkpoint inhibitors (ICIs). The immune-dependent roles of tumor suppressor PTEN in the formation of tumor immune microenvironment remain elusive.Methods: We comprehensively analyzed the genomic and transcriptomic data from multiple ccRCC datasets, including bulk-RNA sequencing and single-cell RNA sequencing data. In vitro, immunoblotting, qRT-PCR, and RNA sequencing were conducted in ccRCC cell lines upon PTEN depletion. Gene ontology and gene set enrichment analysis were performed to screen the critical pathway and molecules in response to PTEN deletion. Immunohistochemistry staining and further bioinformatic analysis were used to validate our data.Results: Based on multi-omics analysis of public datasets of renal cancer, the frequently mutated or deleted PTEN was found to be correlated with a suppressive tumor immune microenvironment in ccRCC. Furthermore, we depleted PTEN via CRISPR-Cas9 in Caki-1 cells, which led to the upregulation of multiple neutrophil chemokines, particularly CXCL1, CXCL2, CXCL5, CXCL6, and CXCL8. The roles of neutrophil chemokines and neutrophil markers were further validated and investigated for the association with prognosis in vitro, clinical samples, and the publicly available databases. The expression of CXCL1, CXCL8, and neutrophil markers, S100A9 and BCL2A1, were significantly associated with a poor immunotherapy-related prognosis in public dataset of renal cancer patients receiving ICIs treatment.Conclusion: These results add a new layer to understanding the association between PTEN status and the role of neutrophil infiltration in ccRCC. Moreover, our findings propose low expression of PTEN as candidate factor of resistance to anti-PD-1-based immunotherapy in ccRCC.Keywords: PTEN, kidney cancer, CXCL1, renal cancer, prognosis

To provide an insight into the oxidation behavior of cysteines in myofibrillar proteins (MPs) during microwave heating (MW), a quantitative redox proteomic analysis based on the isobaric iodoacetyl tandem mass tag technology was applied in this study. MPs from silver carp muscles were subjected to MW and water bath heating (WB) with the same time-temperature profiles to eliminate the thermal differences caused by an uneven energy input. Altogether, 422 proteins were found to be differentially expressed after thermal treatments as compared to that with no heat treatment. However, MW triggered a larger number of proteins and cysteine sites for oxidation. Myosin heavy chain, myosin-binding protein C, nebulin, α-actinin-3-like, and titin were found to be highly susceptible to oxidation under microwave irradiation. Notably, MW caused such modifications at cysteine site 9 in the head of myosin, revealing the enhancement mechanism of MP gelation by excess cysteine cross-linking during microwave processing. Furthermore, Gene Ontology and functional enrichment analyses suggested that the two thermal treatments resulted in some differences in ion binding, muscle cell development, and protein-containing complex assembly. Overall, this study is the first to report the redox proteomic changes caused by MW and WB treatments, thus providing a further understanding of the microwave-induced oxidative modifications of MPs.

Home cooking has been considered as an indoor pollution problem since cooking oil fumes contain various toxic chemicals such as aldehydes. Fortifying edible oils with docosahexaenoic acid (DHA) has been applied to enhance the nutritional value of oils. This study designed a frying simulation system and examined the effect of oil type, DHA fortification, heating time, and addition of natural antioxidant on the emissions of aldehydes from heated oils. Results showed that linseed oil had the highest total aldehyde emissions, followed by soybean oil, peanut oil, and palm oil. Fortifying soybean oil with DHA increased the toxic aldehydes emitted. Quercetin, a flavonoid, significantly reduced aldehydes emitted from DHA-fortified soybean oil (by up to 39.80%) to levels similar to those of normal soybean oil. Further analysis showed that DHA-fortified soybean oil with quercetin had a significantly higher DHA and unsaturated fatty acids (UFAs) content than the control oil at each heating time point. The result indicated that quercetin inhibited emissions of aldehydes, at least in part, by protecting UFAs from oxidation. Collectively, quercetin could be used as a natural additive in DHA-fortified and normal cooking oils to reduce aldehyde emissions, indoor air pollution, and preserve functional DHA and other UFAs.

Background Maillard reaction in foods gives rise to toxic byproducts such as heterocyclic amines (HCAs), acrylamide (AA) and advanced glycation end products (AGEs). Inhibition of their formation during thermal processing is the most practical way to minimize their dietary exposure and thus the associated health risks. Various effective strategies have been proposed, especially with the use of exogenous additives such as polyphenols and emerging hydrocolloids. Hydrocolloids have attracted increasing attention due to their unique structural diversities that enable them to actively participate in Maillard reaction to mitigate the formation of toxic byproducts. They also have the potential to attenuate the harmful effects of these toxic byproducts. Hence, hydrocolloids represent an important class of food ingredients with dual beneficial potential, whereas a systematic review is currently lacking. Scope and approach This review summarizes influencing factors (precursors, processing methods and parameters, and exogenous additives) of thermally induced toxicants (HCAs, AA and AGEs) formation, as well as inhibitory strategies emphasizing on the effects and potential inhibitory mechanism of hydrocolloids. The ability of hydrocolloids to attenuate their harmful effects is also highlighted. Key findings and conclusions Hydrocolloids, alone or in combination with other purported inhibitors of harmful Maillard reaction products (MRPs), may be used in form of powders or aqueous solution for pretreatment of food. Moreover, their water-holding and gelling properties render them suitable for application in form of coatings that may offer additional benefits (e.g. reduction of oil uptake during frying) besides inhibiting the formation of hazardous MRPs. Although a reasonable number of studies have demonstrated the effectiveness of hydrocolloids against both the formation and the harmful effects of Maillard byproducts, more detailed and systematic analyses are needed to clearly characterize their structure-activity relationships and their mechanisms of action.

Background Recently, fatty fish have been utilized as a potential approach for the fabrication of surimi products, with the yield of fatty fish surimi being > 10 000 tons in 2019. However, the gelling properties of catfish surimi can be influenced by intermuscular lipid. Lipase could effectively enhance the gel quality of catfish surimi gels, although the chemical forces involved in gel formation and alteration in lipid and protein oxidation status are not well understood. The present study investigated the gelation-enhancing effects of lipase on catfish surimi based on changes in chemical oxidation interactions. Results The addition of 7.5 g kg-1 lipase significantly increased the hydrophobic interactions and disulfide bond contents, both of which facilitated gel formation, in surimi gels. The 2-thiobarbituric acid reactive substance and carbonyl concentrations demonstrated that lipase promoted lipid and protein oxidations. Furthermore, an appropriate dose of malondialdehyde accelerated protein oxidation, thereby resulting in the covalent cross-linking of proteins. Consequently, the gel strength increased from 55.72 to 127.71 g × cm with lipase contents of up to 7.5 g kg-1 , and strong chemical cross-linking and a compact network were observed via sodium dodecyl sulfate polyacrylamide gel electrophoresis and scanning electron microscopy. However, excessive oxidation led to the degeneration of the gel matrix. A schematic mechanism, mainly based on the chemical changes, is proposed. Conclusion The present study revealed the gelation mechanism of catfish surimi gels with lipase, and suggested that lipase treatments may be an effective approach for improving the textural properties of fatty fish surimi gels. © 2021 Society of Chemical Industry.

In this research, we studied the antioxidative properties and chemical changes of quercetin in fish oil during accelerated storage at 60 °C for 5 days. Gas chromatography (GC) analysis showed that quercetin inhibited aldehyde formation and unsaturated fatty acid oxidation in fish oil significantly; however, the inhibitory effects decreased gradually with prolonged heating time. Moreover, quercetin was consumed with increasing heating time. Some new phenolic derivatives were discovered in the fish oil with quercetin, with their structures fully elucidated by LC-MS/MS and comparison with newly synthesized ones (characterized by MS and NMR spectroscopy). Based on their chemical structures, we proposed that quercetin reacted with EPA and DHA to form the corresponding quercetin fatty acid esters in fish oil. In addition, the newly formed quercetin-3-O-eicosapentaenoate and quercetin-3-O-docosahexaenoate showed weaker DPPH and ABTS radical cation scavenging activity but much improved lipophilicity, higher cell membrane affinity, and hence enhanced cellular antioxidant activity compared with the parent quercetin. Overall, quercetin could be used as a safe dietary polyphenol to inhibit lipid oxidation. The newly formed quercetin-polyunsaturated fatty acid esters may render improved bioactivity to humans, which needs further investigation.

Background Starch is a vital component of the human diet and is widely used in food manufacturing. Its complex and subtle structure influences its physicochemical properties, thus affecting its application. Microwave heating has experienced increased popularity in the food industry for many diverse uses. Dielectric properties are crucial parameters reflecting the response of food to microwave treatment. Recent studies have often neglected the importance of dielectric properties when investigating the structural changes of starch in a microwave field. Scope and approach This review summarizes the dielectric and microwave absorption properties of starches and starch systems (with water and/or ions). The various possible structural changes of starch under a microwave field are also analyzed, from the macroscopic to the microscopic level (morphology, lamellar structure, crystalline structure and molecular structure), in an attempt to elucidate the essential features of the response of starch to microwave heating in terms of the dielectric properties. Key findings and conclusions Microwaves can directly or indirectly induce a series of changes in the morphology and internal structures of starch granules, closely related to the dielectric properties of the system and microwave input energy. The future research trend will be to regulate and manipulate the structural changes of microwave-treated starch systems from the perspective of changing their dielectric properties and to obtain microwave-treated starch-based food with desirable properties.

The aim of this work was to investigate the role of microwave on myosin aggregation during different heating process and to explore the potential relationship between conformation changes and physicochemical properties of myosin. Microwave heating lead to the increasing of turbidity of myosin, but this result was largely influenced by the temperature. Surface hydrophobicity were the dominant binding forces in the formation of myosin aggregation. However, the disulfide bonds play a much more important role in the protein aggregation forming in heat treatment at 60 and 90 °C. Circular dichroism revealed that microwave heating considerably altered the secondary structure of myosin. The gradual disappearance of negative peaks at 202 and 222 nm indicated that a significant decrease in α-helix formation. Particle size distribution and atomic force microscopy analyses demonstrated a more rapid myosin aggregation in response to the microwave treatment at 60 and 90 °C. These results helps to better understand the gel formation mechanism of surimi under microwave field and to improve myosin-based food quality by using microwave treatment.

Although gemcitabine (GEM) has been used to treat bladder cancer (BC) for a number of years, severe adverse events or drug resistance frequently develops. A series of drugs have been proved to sensitize patients to GEM and reduce the side effects. The aim of the present study was to evaluate the potential effects of berberine (BER) on GEM‑induced cytotoxicity in BC and to explore the possible underlying mechanisms. T24 and 5637 human BC cell lines were treated with GEM and/or BER before cell proliferation, apoptosis and migration were studied. Oncomine databases and Gene Expression Profiling Interactive Analysis (GEPIA) were used to retrieve RAD51 recombinase (Rad51) mRNA expression. Overexpression plasmid or specific Rad51 small interfering RNA were used to examine the role of Rad51 in drug‑treated BC cells. BC model mice were administered with GEM and/or BER before changes in tumor volume, size and Ki67 expression were assessed. BER enhanced GEM‑induced cytotoxicity, apoptosis and inhibition of migration, whilst attenuating the GEM‑induced upregulation of phosphorylated Akt and Rad51 expression. According to Oncomine and GEPIA analyses, Rad51 was found to be significantly upregulated in BC tissues compared with that in normal tissues, where there was a weak positive correlation between Rad51 and Akt1 expression. Knockdown of Rad51 enhanced GEM‑induced cytotoxicity, whilst overexpression of Rad51 reversed the suppressed cell viability induced by BER and GEM. Inactivation of the PI3K/Akt pathway by LY294002 or BER enhanced GEM‑induced cytotoxicity and downregulated Rad51 expression, whilst overexpression of constitutively active Akt restored Rad51 expression and cell viability that was previously decreased by BER and GEM. BER additively inhibited tumor growth and Ki67 expression when combined with GEM

The effects of the deacetylation degree (DD) of chitosan on heterocyclic aromatic amine formation were investigated in chemical models and beef patties. The results in model systems showed that at lower addition levels (10 mg), chitosan with 85% DD showed the strongest inhibitory effect against 2-amino-1-methyl-6-phenylimidazo[4,5

Soybean protein pastes were preheated for different times (20, 25 and 30 min) with l-cysteine to improve the printability and self-gelation properties and to explore the relationship between the degree of denaturation and the feasibility of microwave 3D printing. As the pre-denaturation degree increased, ordered secondary structures in proteins gradually decreased, and tertiary structures unfolded. Soybean protein printability, moulding quality increased, and soybean protein, which is not suitable for printing in its natural state, achieved self-gelling after 3D printing. Soybean protein pastes preheated for 25 min with l-cysteine achieved a complete hollow sphere structure compared to other formulations, while pastes preheated for 30 min formed a coarser structure, and blockage occurred during printing. The covalent bond of ε- (γ-glutamine) formed by the synergistic effect of transglutaminase (TGase) and microwaves was the main force driving the gel network structure formation. The most suitable pre-denaturation degree of soybean protein was quantitatively characterized as 57 %.

The aim of this study was to investigate the effect of microwave heating on gel properties of low-acetyl gellan and to explore the potential mechanism of gelation behavior under microwave irradiation. Microwave heating dramatically enhanced the gel strength, hardness of low-acetyl gellan. Microwave-heated gels still formed strong network structures with 30 mM Ca

Exposure to acrolein, one environmental and dietary pollutant, has been shown to cause inflammation. Here, we reported for the first time that acrolein aggravated lipopolysaccharide (LPS)-induced inflammation in Human umbilical vein endothelial cells (HUVEC) as evidenced by the further increased mRNA expression of three pro-inflammatory cytokines, including interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Acrolein also further increased the generation of reactive oxygen species (ROS) and decreased the activity of glutathione peroxidase (GSH-Px) in LPS-pretreated HUVEC. Moreover, acrolein treatment further increased the nucleotide oligomerization domain-like receptor protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) expression, caspase-1 cleavage, and downstream matures interleukin 18 (IL-18) and IL-1β level in LPS-pretreated HUVEC. Acrolein treatment also further increased the expressions of high-mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and phospho-NF-κB P65 (P-P65) in the LPS pre-treated HUVEC. Thus, acrolein aggravated LPS-induced HUVEC inflammation through induction of oxidative stress, and activation of NLRP3 inflammasome and HMGB1/MYD88/NF-κB signaling pathway. In addition, apigenin and apigenin-7, 4'-O-dioctanoate attenuated acrolein-aggravated inflammation by targeting the above signaling pathways. Our findings could help to develop potential therapeutic strategies against acrolein-enhanced inflammation.

To provide an insight into the oxidation behavior of cysteines in myofibrillar proteins (MPs) during microwave heating (MW), a quantitative redox proteomic analysis based on the isobaric iodoacetyl tandem mass tag technology was applied in this study. MPs from silver carp muscles were subjected to MW and water bath heating (WB) with the same time-temperature profiles to eliminate the thermal differences caused by an uneven energy input. Altogether, 422 proteins were found to be differentially expressed after thermal treatments as compared to that with no heat treatment. However, MW triggered a larger number of proteins and cysteine sites for oxidation. Myosin heavy chain, myosin-binding protein C, nebulin, α-actinin-3-like, and titin were found to be highly susceptible to oxidation under microwave irradiation. Notably, MW caused such modifications at cysteine site 9 in the head of myosin, revealing the enhancement mechanism of MP gelation by excess cysteine cross-linking during microwave processing. Furthermore, Gene Ontology and functional enrichment analyses suggested that the two thermal treatments resulted in some differences in ion binding, muscle cell development, and protein-containing complex assembly. Overall, this study is the first to report the redox proteomic changes caused by MW and WB treatments, thus providing a further understanding of the microwave-induced oxidative modifications of MPs.

Chilled surimi has become increasingly popular owing to its superior texture and freshness. In this study, changes in the microbiota and gel properties during chilled surimi storage, and the contributions of dominant bacteria to the physicochemical properties of chilled surimi were investigated. The results showed that Pseudomonas gessardii, Aeromonas media, and Acinetobacter johnsonii were the dominant bacteria during chilled surimi storage. P. gessardii was the key bacteria that degraded protein in the process of surimi spoilage, which led to high total volatile base nitrogen (TVB-N), trichloroacetic acid (TCA)-soluble peptides as well as poor gel properties. Both P. gessardii and A. media were high putrescine producers, whereas only A. media produced cadaverine. In this study, spoilage microorganisms in chilled surimi were investigated for the first time, and it was found that P. gessardii had the greatest influence on surimi quality, which provides a research basis for in-depth study on the mechanism of microbial spoilage and the preservation of chilled surimi.

The existence of microwave non-thermal effects in food processing is still debated. In this study, molecular dynamics (MD) simulations were performed to investigate the conformation, electrostatic profiles, and intramolecular hydrogen bonds (intra-HB) of glucose in aqueous solution under alternating electric fields of microwaves ranging from 0 to 109 V/m at 2.45 GHz. The results showed a field-induced threshold of 109 V/m. At the threshold, alternating microwaves reoriented the flexible moieties and thus enhanced the intra-HB. The conformational transition among gg, gt, and tg conformers at 109 V/m possibly resulted from the uneven electrostatic potential and the increased intra-HB. In practice, the maximum electric field of microwaves is several times weaker than the threshold, verifying the absence of microwave non-thermal effects for glucose molecules in food processing. This study provides a novel strategy to evaluate the potential non-thermal effects of microwaves in food processing and the related underlying food safety issues.

Contamination of rice by cadmium (Cd) is threatening a large population in China. In this study, we report that soaking rice grains in a hydrochloric acid (HCl) solution can remove Cd to a desirable extent. The results indicated that the degree of Cd removal was up to 45%∼85% at different soaking times and concentrations of HCl (0.06 M ∼ 0.18 M), which was found to be logarithmically correlated with the reaction time at the optimized liquid–solid ratio of 1:2. Three HCl concentration-dependent mathematical models were established, which revealed various optimal soaking conditions depending on the initial Cd contamination. Four Cd-contaminated rice grain samples with different degrees of contamination were then tested based on the mathematical models, and the final Cd content was reduced to an acceptable extent. Moreover, the physicochemical and food properties of rice flours and rice grains after Cd removal were evaluated to highlight their potential applications.

To better apply microwave technology to surimi industry, surimi gels of different thicknesses were investigated. According to the determination of electromagnetic properties of surimi paste, both the maximum penetration depth and absorption peak are less than 1 cm. The results of temperature distribution shown that the highest temperature point of the surimi shifted from the center to the periphery. The coefficient of variation (COV) was the minimum and the temperature distribution the temperature distribution was the most uniform when the surimi thickness was 2.0 cm. Surimi paste with a thickness of 2.0 cm heated by microwaves (2450 MHz) had higher gel properties (16.42 ± 0.22 MPa) and water holding capacity (73.59 ± 0.26%) compared to that heated by the traditional water bath method. Scanning electron microscopy revealed that an ordered and dense network structure formed at a thickness of 2 cm. The optimum thickness (2 cm) for microwave heating was determined based on the electromagnetic characteristics and the temperature distribution of surimi, which provided basis for the application of microwave in surimi products.

Dielectric loss (e″) represents the ability to convert electromagnetic energy into heat, which may further affect the degree of Maillard reaction (MR). Based on the differences in electromagnetic response between lysine (Lys) and glucose (Glu), this study aims to verify the e″ -mediated intervention of microwave heating (MW) on different stages of MR by using different reaction solvents. Compared to conventional heating (CV), the systems with MW showed greater e″ and absorbance at both 294 nm (A294nm) and 420 nm (A420nm). Changing the solvent from pure water to a mixture (1:1 vol ratio of water to glycerol), thereby dramatically increasing e″ (by 6.02), compared to pure water (CV), the systems treated with the mixture under MW demonstrated large increases at both A294nm and A420nm, increasing by 0.35 at 10 min and 1.35 at 60 min, respectively. These results suggest that increasing e″ contributes to the promotion of MW during different stages of the MR.

The aim of this work was to investigate the microbial diversity of jiaozi (n = 7) and type I sourdoughs (n = 8) by culture-dependent and culture-independent analysis and explore the effect of these starter cultures on the generation of volatiles in steamed breads. Both starter cultures significantly varied in terms of their pH, TTA and moisture content (P 0.05) was found. The culture-dependent and culture-independent approaches revealed that Weissella cibaria and Lactobacillus sanfranciscensis were predominant in the microbiota of jiaozi and type I sourdoughs, respectively. Saccharomyces cerevisiae and Candida humilis were the most common yeast species in all samples. A total of 36 volatile compounds were detected in all steamed breads. The products fermented with jiaozi had a relative high concentration of volatiles synthesized by amino acid metabolism. However, products fermented with type I sourdough were dominated by acids, furans, aldehydes and their corresponding alcohols. The principal component analysis distinguished the two starter cultures, based on the abundance of bacterial species as well as the total volatile composition of their respective steamed breads. We conclude that the production of volatile compounds strongly correlated with the microbiota involved in fermentation.

To preserve the quality of frozen food products, the main goal of suitable thawing is to cause the least amount of damage with the shortest possible thawing time. A radiofrequency (RF) system has potential for use in achieving these goals for industrial thawing operations. This study investigated the characteristics of RF thawing, and sought to determine the optimal conditions for RF thawing by clarifying the temperature distributions in blocks of frozen minced fish. The dielectric properties (DPs) of frozen minced fish and the penetration depths (dp) of thawing were measured under differing methods and conditions. The temperatures measured by the probes were plotted in Surfer and verified by COMSOL simulation. A sharp increase in DPs (e′ and e″) was observed at a frequency of 27.12 MHz (from −3 °C to 0 °C), and a striking dp was found from −15 °C to −5 °C, Electromagnetic waves at this frequency could penetrate our samples easily, and the uniformity of heating was improved at both ranges of temperature. For the size of frozen minced fish blocks that are commonly used in the industry (25 × 15 × 5 cm), the most suitable electrode gap for thawing was found to be 16 cm. Unlike in the results obtained with other thawing methods, the cooked gel properties after RF thawing were unaffected, which proved that the RF system is optimal for use in industrial production.

The aim of this work was to investigate the role of microwave parameters and moisture content on the free volume (FV) changes of rice starch by positron annihilation lifetime spectroscopy analysis (PALS) and to explore the potential relationship between the changes of FV and physicochemical properties of rice starch. Microwave heating and water molecules lead to the increasing of FV of starch. However, this result is largely influenced by the plasticization of water molecule. The anti-plasticization caused by water evaporation resulting in a decrease in the size and concentration of FV during microwave heating. Significant decrease (p Tg) and gelatinization temperature significantly increase (p Tg of rice starch were strongly related to FV changes. These results provided a theoretical basis for further research on the directional regulation of FV and improvement the quality of starch-based food by using microwave treatment.