Co-immobilization of ß-agarase and α-agarase for degradation of agarose to prepare bioactive 3,6-anhydro-L-galactose.

Agarose from biomass can be used to synthesize the rare sugar 3,6-anhydro-L-galactose (L-AHG), and the new synthesis route and functional properties of L-AHG have always been the focus of research. Here we developed a novel method to co-immobilize Aga50D and BpGH117 onto streptavidin-coated magnetic nanoparticles and achieved the conversion of agarose to bioactive L-AHG in one pot. Results showed that enzymes were successfully immobilized on the carrier. The activity of co-immobilized enzymes was 2.5-fold higher than that of single immobilized enzymes. Compared with free enzymes, co-immobilized enzymes exhibited enhanced thermal stability. The co-immobilized enzymes retained 79.45 % relative activity at 40 °C for 3 h, while the free enzymes only possessed 21.40 % residual activity. After eight cycles, the co-immobilized enzymes still retained 73.47 % of the initial activity. After silica gel chromatography, the purity of L-AHG obtained by co-immobilized enzymes hydrolysis reached 83.02 %. Furthermore, bioactivity experiments demonstrated that L-AHG displayed better antioxidant and antibacterial effects than neoagarobiose. L-AHG had broad-spectrum antibacterial activity, while neoagarobiose and D-galactose did not show an obvious antibacterial effect. This study provides a feasible method for the production of L-AHG by a co-immobilized multi-enzyme system and confirms that L-AHG plays a key role in the bioactivity of neoagarobiose.

Comparative study on different immobilization sites of immobilized ß-agarase based on the biotin/streptavidin system.

ß-Agarase was biotinylated and immobilized onto streptavidin-conjugated magnetic nanoparticles to provide insights into the effect of immobilization sites on ß-agarase immobilization. Results showed that, compared with free enzyme, the stability of prepared immobilized ß-agarases through amino or carboxyl activation were both significantly improved. However, the amino-activated immobilized ß-agarase showed higher thermostability and catalytic efficiency than the carboxyl-activated immobilized ß-agarase. The relative activity of the former was 65.00 % after incubation at 50 °C for 1 h, which was 1.77-fold higher than that of the latter. Additionally, amino-activated immobilization increased the affinity of the enzyme to the substrate, and its maximum reaction rate (0.68 µmol/min) was superior to that of carboxyl-activated immobilization (0.53 µmol/min). The visualization results showed that the catalytic site of ß-agarase after carboxyl-activated immobilization was more susceptible to the immobilization process, and the orientation of the enzyme may also hinder substrate binding and product release. These results suggest that by pre-selecting appropriate activation sites and enzyme orientation, immobilized enzymes with higher catalytic activity and stability can be obtained, making them more suitable for the application of continuous production.

A Versatile Strategy of Designing Gold Nanoparticle-cDNA Nanoprobes in Developing Aptamer-Based Lateral Flow Assay for Small-Molecule Detection.

Aptamer-based lateral flow assay (Apt-LFA) has shown promising applications for small-molecule detection. However, the design of the AuNP (gold nanoparticle)-cDNA (complementary DNA) nanoprobe is still a big challenge due to the moderate affinity of the aptamer to small molecules. Herein, we report a versatile strategy to design a AuNPs@polyA-cDNA (poly A, a repeat sequence with 15 A bases) nanoprobe for small-molecule Apt-LFA. The AuNPs@polyA-cDNA nanoprobe contains a polyA anchor blocker, complementary DNA segment to DNA on the control line (cDNAc), partial complementary DNA segment with aptamer (cDNAa), and auxiliary hybridization DNA segment (auxDNA). Using adenosine 5'-triphosphate (ATP) as a model target, we optimized the length of auxDNA and cDNAa and achieved a sensitive detection of ATP. In addition, kanamycin was used as a model target to verify the universality of the concept. Therefore, this strategy can be easily extended to other small molecules; therefore, high application potential in Apt-LFAs can be envisaged.

Natural antimicrobial oligosaccharides in the food industry.

An increase in the number of antibiotic resistance genes burdens the environment and affects human health. Additionally, people have developed a cautious attitude toward chemical preservatives. This attitude has promoted the search for new natural antimicrobial substances. Oligosaccharides from various sources have been studied for their antimicrobial and prebiotic effects. Antimicrobial oligosaccharides have several advantages such as being produced from renewable resources and showing antimicrobial properties similar to those of chemical preservatives. Their excellent broad-spectrum antibacterial properties are primarily because of various synergistic effects, including destruction of pathogen cell wall. Additionally, the adhesion of harmful microorganisms and the role of harmful factors may be reduced by oligosaccharides. Some natural oligosaccharides were also shown to stimulate the growth probiotic organisms. Therefore, antimicrobial oligosaccharides have the potential to meet food processing industry requirements in the future. The latest progress in research on the antimicrobial activity of different oligosaccharides is demonstrated in this review. The possible mechanism of action of these antimicrobial oligosaccharides is summarized with respect to their direct and indirect effects. Finally, the extended applications of oligosaccharides from the food source industry to food processing are discussed.

Enzymatic preparation and potential applications of agar oligosaccharides: a review.

Oligosaccharides derived from agar, that is, agarooligosaccharides and neoagarooligosaccharides, have demonstrated various kinds of bioactivities which have been utilized in a variety of fields. Enzymatic hydrolysis is a feasible approach that principally allows for obtaining specific agar oligosaccharides in a sustainable way at an industrial scale. This review summarizes recent technologies employed to improve the properties of agarase. Additionally, the relationship between the degree of polymerization, bioactivities, and potential applications of agar-derived oligosaccharides for pharmaceutical, food, cosmetic, and agricultural industries are discussed. Engineered agarase exhibited general improvement of enzymatic performance, which is mostly achieved by truncation. Rational and semi-rational design assisted by computational methods present the latest strategy for agarase improvement with greatest potential to satisfy future industrial needs. Agarase immobilized on magnetic Fe3O4 nanoparticles via covalent bond formation showed characteristics well suited for industry. Additionally, albeit with the relationship between the degree of polymerization and versatile bioactivities like anti-oxidants, anti-inflammatory, anti-microbial agents, prebiotics and in skin care of agar-derived oligosaccharides are discussed here, further researches are still needed to unravel the complicated relationship between bioactivity and structure of the different oligosaccharides.

Non-Conventional Induction Heat Treatment: Effect of Design and Electrical Parameters on Apple Juice Safety and Quality.

The proposed non-conventional induction heating, which combines an MSCP and VDC structure, was proved to have excellent thermal effect. Different from other electric field sterilization, this electrotechnology operates with no electrodes, and it is a continuous-flow process with short-duration (about 20 s). In current study, the parameters related to temperature rise were investigated, including applied voltage, frequency, the diameter of the secondary coil and heating tube, as well as their length, etc. It was demonstrated that a smaller diameter of the heating tube, parallel connection sample coils, and higher frequency were beneficial for the inactivation of microorganisms. At 500 Hz, the optimal condition is 800 V, d1 = 2 mm, and L1 = 10 cm. Notably, the system could inactivate all microorganisms and maintained the physicochemical properties of apple juice at 40 kHz. It suggests that this structural design has the potential for industrial applications and the proposed induction heating can realize the rapid sterilization of liquid food without applying electrodes.

Co-Cultures of Lactobacillus acidophilus and Bacillus subtilis Enhance Mucosal Barrier by Modulating Gut Microbiota-Derived Short-Chain Fatty Acids.

Weaning stress induces intestinal barrier dysfunction and immune dysregulation in mammals. Various interventions based on the modulation of intestinal microbiota have been proposed. Our study aims to explore the effects of co-cultures from Lactobacillus acidophilus and Bacillus subtilis (FAM®) on intestinal mucosal barrier from the perspective of metabolic function of gut microbiota. A total of 180 piglets were allocated to three groups, i.e., a control group (C, basal diet), a FAM group (F, basal diet supplemented with 0.1% FAM), and an antibiotic group (A, basal diet supplemented with antibiotic mixtures). Here, we showed FAM supplementation significantly increased body weight and reduced diarrhea incidence, accompanied by attenuated mucosal damage, increased levels of tight junction proteins, serum diamine oxidase (DAO) and antimicrobial peptides. In addition, 16S rRNA sequencing and metabolomic analysis revealed an increase in relative abundance of Clostridiales, Ruminococcaceae, Firmicutes and Muribaculaceae and a significant increase in the total short-chain fatty acids (SCFAs) and butyric acid in FAM-treated piglets. FAM also increased CD4+ T cells and SIgA+ cells in intestinal mucosa and SIgA production in colon contents. Furthermore, FAM upregulated the expression of IL-22, short-chain fatty acid receptors GPR43 and GPR41, aryl hydrocarbon receptor (AhR), and hypoxia-inducible factor 1α (HIF-1α). FAM shows great application prospect in gut health and provides a reference for infant weaning.

Non-thiolated nucleic acid functionalized gold nanoparticle-based aptamer lateral flow assay for rapid detection of kanamycin.

A novel Apt-LFA has been established for kanamycin based on non-thiolated nucleic acid-modified colloidal gold nanoprobe (AuNPs@polyA-DNA). The improvement in nucleic acid hybridization speed and efficiency was verified by modifying AuNPs with polyA-DNA strands instead of thiolated oligonucleotides (SH-DNA) strands. Moreover, the AuNPs@polyA-DNA was explored to apply in an Apt-LFA. The experimental factors including the concentration of the aptamer, the concentration of SA-DNAT conjugate, the incubation time, and temperature were carefully investigated. In addition, the kanamycin aptamer was modified by extending several bases at its end to modulate the hybridization complementary strand, which was found to significantly improve the performance of Apt-LFA. Under optimal experimental conditions, the Apt-LFA can detect kanamycin in honey with a LOD of 250 ng mL-1 by the naked eyes. A linear range of 50-1250 ng mL-1 was obtained with a LOD of 15 ng mL-1 in honey by a portable reader. The Apt-LFA was successfully applied to the detection of kanamycin in honey with recoveries of 95.1-105.2%.

Design and optimizing gold nanoparticle-cDNA nanoprobes for aptamer-based lateral flow assay: Application to rapid detection of acetamiprid.

The aptamer-based lateral flow assay strips (Apt-LFAs) have shown promising application prospects in the detection of small molecules. The general principle of Apt-LFAs used for the detection of small molecules is based on the target-induced dissociation (TID) competitive binding among the aptamer, target and gold nanoparticle (AuNP)-complementary DNA (cDNA) nanoprobes. One of the most important components in this device is AuNP-cDNA nanoprobe, which has strong effect on the sensitivity and specificity of Apt-LFAs. In this report, we designed an AuNPs@polyA-cDNA nanoprobe, which consists of a poly adenine (polyA) anchor blocker, a partial complementary DNA fragment to aptamer strand (cDNAa) and complementary DNA fragment to control DNA strand (cDNAc), for rapid detection of acetamiprid. cDNAa of AuNPs@polyA-cDNA nanoprobe was carefully investigated in terms of the hybridization site and length with the aptamer. A specific cDNAa sequence containing key binding bases of acetamiprid aptamer was obtained and verified by molecular docking analysis. After systematic optimization, the Apt-LFA was able to detect a minimum concentration of 0.33 ng mL-1 acetamiprid. The Apt-LFA was successfully applied to detect spiked acetamiprid in tomato and rape samples with the recoveries ranged from 94 to 106%. Based on the strong versatility and verified molecular interaction mechanism, the design strategy could be extended to develop various Apt-LFAs for other small molecules.

Inactivation of Escherichia coli O157:H7 in apple juice via induced electric field (IEF) and its bactericidal mechanism.

Non-conventional heating technology based on electric fields can be utilized to process liquid foods. In this study, the induced electric field (IEF) was investigated to clarify its inactivation mechanism on E.coli. Staining results show that inactivation of E.coli by IEF can be attributed to the reversible destruction of the cell membrane, followed by the denaturation of intracellular enzymes, and finally the irreversible rupture of the cell membrane. The increased levels of extracellular proteins and nucleic acids were also observed. IEF treatment at 400 Hz and 800 V (or 53 V/cm) results in a reduction of 4.5 log CFU·mL-1 in the number of E.coli. Storage life analysis shows that IEF treatment can improve the stability of apple juice and the content of bioactive components. Thus, IEF is a potential technique for liquid food processing.

Ethnicity-stratified analysis of the association between XRCC3 Thr241Met polymorphism and leukemia: an updated meta-analysis.

BACKGROUND: Presently, whether X-ray repair cross complementing group 3 (XRCC3) Thr241Met polymorphism is correlated to leukemia risk remains controversial. Because of this reason, the objective of current study is to explore whether XRCC3 Thr241Met polymorphism confers risk to leukemia. METHODS: Two independent authors systematically and comprehensively searched Pubmed, Embase, the Cochrane library, Google academic, China National Knowledge Infrastructure (CNKI). Search time is from database foundation to March 2021. RESULTS: Overall, significant associations between leukemia risk and XRCC3 Thr241Met polymorphism were found in Caucasian population by allele contrast (T vs. C: OR 1.20, 95% CI 1.02-1.40), homozygote comparison (TT vs. CC: OR 1.35, 95% CI 1.05-1.73), and recessive genetic model (TT vs. TC/CC: OR 1.31, 95% CI 1.04-1.64). CONCLUSIONS: The present meta-analysis suggests that the XRCC3 Thr241Met polymorphism may be a risk factor for leukemia in Caucasian population.

Maternal galactooligosaccharides supplementation programmed immune defense, microbial colonization and intestinal development in piglets.

The benefits of galactooligosaccharides (GOS) in neonates have been confirmed. However, the effects of nutritional programming by maternal GOS intervention on microbial colonization and intestinal development in the offspring remain unclear. In the present study, late gestational sows were fed with GOS (10 g d-1 added into the diet) or not until parturition, and the performances, immune status, microbiota composition and intestinal barriers in their piglets on day 21 were compared. GOS supplementation in pregnant sows improved their litter characteristics and the growth performance of their piglets during the neonatal stage (day 21), and elevated the plasma IgA levels in both sows and their piglets (P < 0.05). GOS intervention enriched fecal Alloprevotella and Ruminoclostridium_1 in gestational sows and vertically increased fecal Alloprevotella and Ruminococcaceae in their piglets (P < 0.05). Moreover, maternal GOS intervention increased fecal acetate (P < 0.05) and improved the intestinal barriers of their piglets by upregulating intestinal tight junctions (Occludin, Claudin-1, ZO-1), the goblet cell number and Mucin-2 (P < 0.05), which correlated positively with the colonized microbiota (P < 0.05). In summary, GOS supplementation for sows during late gestation nutritionally programmed maternal specific microbes and IgA of their offspring. This neonatal programming showed positive potential in promoting the intestinal barriers, immune defense, and growth performance of the piglets. Our findings provide evidence for maternal nutritional programming in neonates and insights for future application of GOS in maternal-neonatal nutrition.

Efficient Laser-Induced Construction of Oxygen-Vacancy Abundant Nano-ZnCo2 O4 /Porous Reduced Graphene Oxide Hybrids toward Exceptional Capacitive Lithium Storage.

Recently, binary ZnCo2 O4 has drawn enormous attention for lithium-ion batteries (LIBs) as attractive anode owing to its large theoretical capacity and good environmental benignity. However, the modest electrical conductivity and serious volumetric effect/particle agglomeration over cycling hinder its extensive applications. To address the concerns, herein, a rapid laser-irradiation methodology is firstly devised toward efficient synthesis of oxygen-vacancy abundant nano-ZnCo2 O4 /porous reduced graphene oxide (rGO) hybrids as anodes for LIBs. The synergistic contributions from nano-dimensional ZnCo2 O4 with rich oxygen vacancies and flexible rGO guarantee abundant active sites, fast electron/ion transport, and robust structural stability, and inhibit the agglomeration of nanoscale ZnCo2 O4 , favoring for superb electrochemical lithium-storage performance. More encouragingly, the optimal L-ZCO@rGO-30 anode exhibits a large reversible capacity of ≈1053 mAh g-1 at 0.05 A g-1 , excellent cycling stability (≈746 mAh g-1 at 1.0 A g-1 after 250 cycles), and preeminent rate capability (≈686 mAh g-1 at 3.2 A g-1 ). Further kinetic analysis corroborates that the capacitive-controlled process dominates the involved electrochemical reactions of hybrid anodes. More significantly, this rational design holds the promise of being extended for smart fabrication of other oxygen-vacancy abundant metal oxide/porous rGO hybrids toward advanced LIBs and beyond.

Hierarchical Ti3C2@TiO2 MXene hybrids with tunable interlayer distance for highly durable lithium-ion batteries.

To realize high-rate and long-term performance of rechargeable batteries, the most effective approach is to develop an advanced hybrid material with a stable structure and more reaction active sites. Recently, 2D MXenes have become an up-and-coming electrode owing to their high conductivity and large redox-active surface area. In this work, we firstly prepared Ti3C2 MXenes through the selective etching of silicon from Ti3SiC2 (MAX) using HF and an oxidant for highly durable lithium-ion batteries (LIBs). The interlayer distance of Ti3C2 MXenes can be controlled with the oxidizability of the oxidant and etching temperature. In addition, Ti3C2@TiO2 MXene hybrids with further expanded interlayer spacing were purposefully fabricated by a simple hydrothermal method. The hierarchical N-doped Ti3C2@TiO2 MXene hybrids show that the in situ synthesized nanoscale TiO2 particles are loaded homogeneously on the layered N-doped Ti3C2 surface. The interlayer distance of N-doped Ti3C2@TiO2 MXene can reach 12.77 Å when using HNO3 as the oxidant at room temperature. As an anode material, the N-doped Ti3C2@TiO2(HNO3-RT) hybrid displays a high reversible capacity of 302 mA h g-1 at 200 mA g-1 after 500 cycles and 154 mA h g-1 at 2000 mA g-1 after 1500 cycles, which indicates its long cycle lifetime and excellent stability in LIBs. This highly durable LIB anode performance is ascribed to synergetic contributions from the high capacitive contribution, high electrical conductivity, high-capacity of in situ formed nanoscale TiO2 and interlayer-expanded architecture of the N-doped Ti3C2@TiO2(HNO3-RT). This study provides a theoretical basis for the application of MXenes as high capacity anodes for advanced LIBs.

Effects of induced electric field (IEF) on the reduction of Saccharomyces cerevisiae and quality of fresh apple juice.

The non-conventional technologies about continuous sterilization of liquid food were focused on recently, which is benefits for industrialization. In this study, the machine with an induced electric field was used to sterilize S. cerevisiae in apple juice and the juice quality also was researched. The optimal condition is 800 V, 400 Hz, 5 rpm and 2 mm. Furthermore, the sterilization of the IEF was attributed to non-thermal and thermal effects. The IEF treatment group has a reduction of about 4.6 logs (CFU/mL) in S. cerevisiae at 400 Hz, 800 V, and 2 mm, while the non-thermal group is nearly 2 logs (CFU/mL). The improvement of conductivity and the reduction of pH value imply that IEF might destroy the cell structure. Meanwhile, polyphenol compounds and amino acids in the IEF group were protected well than other groups. Generally, IEF is a potential technology for industrial sterilization of liquid beverages.

Colorimetric determination of Pb2+ ions based on surface leaching of Au@Pt nanoparticles as peroxidase mimic.

We report the first use of metallic nanozyme as colorimetric probe for Pb2+ determination. The method is based on the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanied by a decreased catalytic activity of the metallic nanozyme. To construct this colorimetric determination, the Pt deposition onto the AuNPs was carefully investigated and other experimental factors including kind of substrate and buffer were optimized. With increasing Pb2+ concentration, the catalytic activity of the Au@PtNPs decreased gradually. As a result, the blue color at 650 nm from the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 faded gradually. A determination limit of 3.0 nM Pb2+ with a linear range from 20 to 800 nM was obtained. The assay demonstrated negligible response to common metal ions even at elevated concentrations. This colorimetric method was applied to the determination of Pb2+ ions spiked in lake water samples, and good recoveries (96.8-105.2%) were obtained. The above results indicate the potential application of metallic nanozymes in developing robust colorimetric assays. Graphical abstract Schematic representation of the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanying the decreased catalytic activity of the metallic nanozyme.

Maternal Diet-Induced Obesity Compromises Oxidative Stress Status and Angiogenesis in the Porcine Placenta by Upregulating Nox2 Expression.

Maternal obesity is associated with placental oxidative stress. However, the mechanism underlying this association remains poorly understood. In the present study, a gilt obesity model was developed by exposure to different energy diets and used to investigate the role of NADPH oxidase 2 (Nox2) in the placenta. Specifically, 99 gilts (Guangdong Small-ear Spotted pig) at day 60 of gestation were randomly assigned to one of the following three treatments: low-energy group (L, DE = 11.50 MJ/kg), medium-energy group (M, DE = 12.41 MJ/kg), and high-energy group (H, DE = 13.42 MJ/kg), with 11 replicate pens per treatment and 3 gilts per pen. At the start of the study, maternal body weight and backfat thickness were not significantly different in the three treatments. After the study, data indicated that the H group had higher body weight and backfat thickness gain for gilts during gestation and lower piglet birth weight compared with the other two groups. Additionally, the H group showed glucolipid metabolic disorders and increased triglyceride and nonesterified fatty acid contents in the placenta of gilts. Compared with the L group, the H group exhibited lower mitochondrial biogenesis and increased oxidative damage in the placenta. Importantly, increased mRNA expression and protein abundance of Nox2 were observed for the first time in H group placentae. Furthermore, compared with the L group, the H group showed a decrease in the density of placental vessels and the protein levels of vascular endothelial cadherin (VE-cadherin), vascular endothelial growth factor A (VEGF-A), and phosphorylation of vascular endothelial growth factor receptor 2 (p-VEGFR2) as well as the immunostaining intensity of platelet endothelial cell adhesion molecule-1 (CD31). Our findings suggest that maternal high-energy diet-induced obesity increases placental oxidative stress and decreases placental angiogenesis possibly through the upregulation of Nox2.

Effective production of lactosucrose using ß-fructofuranosidase and glucose oxidase co-immobilized by sol-gel encapsulation.

The production of lactosucrose is hampered by the costly use of ß-fructofuranosidase, which shows poor stability and a low efficiency in transfructosylation activity. Immobilization could improve enzyme stability and realize the cyclic utilization at a reduced cost. In order to eliminate the by-product inhibition and improve the transfructosylation efficiency, ß-fructofuranosidase and glucose oxidase were co-immobilized by sol-gel encapsulation and the subsequent production efficiency of lactosucrose was investigated. The as-prepared immobilized bi-enzymes retained 85.39% of their initial activity at an enzyme concentration of 1.47 mg/g·sol during immobilization and showed great operational stability (maintaining 78.5% of their initial activity) after 15 consecutive reuses. The yield of lactosucrose synthesized by immobilized bi-enzymes reached 160.8 g/L under the optimized conditions, which was relatively higher than previous reported results. Moreover, the yield of lactosucrose synthesized by immobilized bi-enzymes was significantly improved as compared to that synthesized by immobilized ß-fructofuranosidase. HPLC and NMR spectrum results confirmed the presence of lactosucrose during immobilized bi-enzymes catalysis. Furthermore, a relatively high purity of lactosucrose was obtained (87.4% determined by HPLC) after separation with Diaion UBK535 calcium ester resin, and the optimal conditions for separation of lactosucrose were investigated. These results indicated that the co-immobilization of ß-fructofuranosidase-glucose oxidase was helpful to improve the production of lactosucrose with low costs, which can be used in continuous lactosucrose production in food industry in advantages of high stability and reusability. And the as-prepared lactosucrose with high purity can be applied to many kinds of food as functional additives.

Influence of uniform magnetic field on physicochemical properties of freeze-thawed avocado puree.

External fields are reported to have the potential to improve the quality of food after freeze-thawing. This study investigated the effect of an oscillating magnetic field with high uniformity and multi-directions at 4 mT and 50 Hz on the freezing of avocado puree. Samples of avocado puree were placed in the central zone of three pairs of orthometric Helmholtz coils where a highly homogeneous degree (99% homogeneity) magnetic field could be guaranteed. For comparison, avocado puree was frozen without the magnetic field. According to the freezing curve, under the magnetic field, the freezing point of avocado puree was decreased from -1.2 to -6 °C, which indicated that the temperature zone for maximum ice crystal formation was reduced. The uniform magnetic field had a positive effect on the avocado puree. The pH value of the samples after the magnetic field-assisted freezing was higher than that of the control. With the increase in the magnetic field direction, ΔE gradually decreased. In addition, the antioxidant activity of the puree significantly decreased, and the diphenylpicrylhydrazyl (DPPH) radical scavenging activity decreased from 69.18% to 56.22%, whereas the ferric reducing antioxidant power (FRAP) value decreased from 18.5% to 14.75%. However, the three-direction magnetic field-assisted freezing could better maintain the antioxidant activities of avocado puree. Moreover, the interaction of ferrous gluconate and multi-directional magnetic field could exert an improvement on the quality of freeze-thawed avocado puree, owing to the small molecular current.

Determination of fat content in UHT milk by electroanalytical method.

An electroanalytical method was proposed to determine fat content in ultrahigh-temperature (UHT) processed milk by magnetoelectric induction. In the technique, involves the induction of a controllable voltage (potential difference, Ubc) in UHT milk, with differential magnetic fluxes as the stimulus. Results indicated that Ubc increased with an increase in the ratio difference between primary coil 1 and primary coil 2. Variation of fat content in the UHT milk induced a change in Ubc. A reduction in fat content led to an increase in λ-value (ratio of Uab to excitation voltage) under specific conditions. For calibration and verification, a high linear correlation coefficient (R2 = 0.9428) and a low root-mean-square error of cross-validation (0.342 g/100 g) were observed between milk fat and λ-value at 20 V and 700 Hz under an open circuit at a coil ratio of 14:56. Measurement sensitivity was improved with the increase of the sample coils.