High oxidative stability of a complex fish liver oil nano-capsules in response to long-term storage, and to hyperthermal and sunlight exposure.

BACKGROUND: In this study, a biocompatible nano-carrying platform using chitosan (ChI) and chondroitin sulfate (ChS) was developed for the encapsulation of cobia liver oil (CBLO) to prevent its oxidation and improve its absorption. An ionic gelation method was applied to encapsulate CBLO with different weight ratios (from 1.0 to 1.5) to obtain ChS-ChI nano-capsules (ChS-ChI@CBLO NCs). RESULTS: Morphological observations of the nano-capsules revealed a spherical shape and diameter around 267-381 nm. The maximum loading capacity (LC) and encapsulation efficiency (EE) for ChS-ChI@CBLO NCs estimated by thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis were 25.7% and 56.2%, respectively. The structural stability of ChS-ChI@CBLO NCs was confirmed through differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis; moreover DSC also further confirmed the oxidative stability of ChS-ChI@CBLO NCs. Fourier-transform infrared (FTIR) spectra confirmed the excellent stability of ChS-ChI@CBLO NCs against high temperature and sunlight exposure. Biocompatibility analysis also verified the non-toxicity of ChS-ChI@CBLO NCs, further indicating safety and potential application in complex-nutritional supplements. CONCLUSION: Nano-degree of ChS-ChI@CBLO NCs has a loading capacity and encapsulation efficiency of around 16.5 ~ 25.7% and 33.4 ~ 56.2%, respectively, for encapsulation of CBLO. Characterization results also indicate that ChS-ChI@CBLO NCs display high oxidative stability against long-term, hyperthermal, and sunlight exposure. Bioassay results confirm that the ChS-ChI@CBLO NCs are safe and non-toxic. This study demonstrates that nano-capsules are also beneficial in preventing sensitive compounds from metamorphosis, and are non-toxic. These materials are suitable for use in the food and pharmaceutical industries. © 2023 Society of Chemical Industry.

Synthesis and Anticancer Evaluation of 4-Anilinoquinolinylchalcone Derivatives.

A series of 4-anilinoquinolinylchalcone derivatives were synthesized and evaluated for antiproliferative activities against the growth of human cancer cell lines (Huh-7 and MDA-MB-231) and normal lung cells (MRC-5). The results exhibited low cytotoxicity against human lung cells (MRC-5). Among them, (E)-3-{4-{[4-(benzyloxy)phenyl]amino}quinolin-2-yl}-1-(4-methoxyphenyl) prop-2-en-1-one (4a) was found to have the highest cytotoxicity in breast cancer cells and low cytotoxicity in normal cells. Compound 4a causes ATP depletion and apoptosis of breast cancer MDA-MB-231 cells and triggers reactive oxygen species (ROS)-dependent caspase 3/7 activation. In conclusion, it is worth studying 4-anilinoquinolinylchalcone derivatives further as new potential anticancer agents for the treatment of human cancers.

Effect of Oversulfation on the Composition, Structure, and In Vitro Anti-Lung Cancer Activity of Fucoidans Extracted from Sargassum aquifolium.

Intensive efforts have been undertaken in the fields of prevention, diagnosis, and therapy of lung cancer. Fucoidans exhibit a wide range of biological activities, which are dependent on the degree of sulfation, sulfation pattern, glycosidic branches, and molecular weight of fucoidan. The determination of oversulfation of fucoidan and its effect on anti-lung cancer activity and related signaling cascades is challenging. In this investigation, we used a previously developed fucoidan (SCA), which served as a native fucoidan, to generate two oversulfated fucoidan derivatives (SCA-S1 and SCA-S2). SCA, SCA-S1, and SCA-S2 showed differences in compositions and had the characteristic structural features of fucoidan by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses. The anticancer properties of SCA, SCA-S1, and SCA-S2 against human lung carcinoma A-549 cells were analyzed in terms of cytotoxicity, cell cycle, Bcl-2 expression, mitochondrial membrane potential (MMP), expression of caspase-3, cytochrome c release, Annexin V/propidium iodide (PI) staining, DNA fragmentation, and the underlying signaling cascades. Our findings indicate that the oversulfation of fucoidan promotes apoptosis of lung cancer cells and the mechanism may involve the Akt/mTOR/S6 pathway. Further in vivo research is needed to establish the precise mechanism whereby oversulfated fucoidan mitigates the progression of lung cancer.

Physicochemical and Antioxidant Properties of Gelatin and Gelatin Hydrolysates Obtained from Extrusion-Pretreated Fish (Oreochromis sp.) Scales.

Fish gelatin and its hydrolysates exhibit a variety of biological characteristics, which include antihypertensive and antioxidant properties. In this study, fish gelatins were extracted from extrusion-pretreated tilapia scales, and then subjected to analyses to determine the physicochemical properties and antioxidant activity of the extracted gelatins. Our findings indicate that TSG2 (preconditioned with 1.26% citric acid) possessed the greatest extraction yield, as well as higher antioxidant activities compared with the other extracted gelatins. Hence, TSG2 was subjected to further hydrolyzation using different proteases and ultrafiltration conditions, which yielded four gelatin hydrolysates: TSGH1, TSGH2, TSGH3, and TSGH4. The results showed that TSGH4 (Pepsin + Pancreatin and ultrafiltration < 3000 Da) had a higher yield and greater antioxidant activity in comparison with the other gelatin hydrolysates. As such, TSGH4 was subjected to further fractionation using a Superdex peptide column and two-stage reverse-phase column HPLC chromatography, yielding a subfraction TSGH4-6-2-b, which possessed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity compared with the other fractions. Further LC-ESI/MS/MS analysis of TSGH4-6-2-b suggested two novel peptides (GYDEY and EPGKSGEQGAPGEAGAP), which could have potential as naturally-occurring peptides with antioxidant properties. These promising results suggest that these antioxidant peptides could have applications in food products, nutraceuticals, and cosmetics.

Degradation of Sargassum crassifolium Fucoidan by Ascorbic Acid and Hydrogen Peroxide, and Compositional, Structural, and In Vitro Anti-Lung Cancer Analyses of the Degradation Products.

Fucoidans possess multiple biological functions including anti-cancer activity. Moreover, low-molecular-weight fucoidans are reported to possess more bioactivities than native fucoidans. In the present study, a native fucoidan (SC) was extracted from Sargassum crassifolium pretreated by single-screw extrusion, and three degraded fucoidans, namely, SCA (degradation of SC by ascorbic acid), SCH (degradation of SC by hydrogen peroxide), and SCAH (degradation of SC by ascorbic acid + hydrogen peroxide), were produced. The extrusion pretreatment can increase the extraction yield of fucoidan by approximately 4.2-fold as compared to the non-extruded sample. Among SC, SCA, SCH, and SCAH, the chemical compositions varied but structural features were similar. SC, SCA, SCH, and SCAH showed apoptotic effects on human lung carcinoma A-549 cells, as illustrated by loss of mitochondrial membrane potential (MMP), decreased B-cell leukemia-2 (Bcl-2) expression, increased cytochrome c release, increased active caspase-9 and -3, and increased late apoptosis of A-549 cells. In general, SCA was found to exhibit high cytotoxicity to A-549 cells and a strong ability to suppress Bcl-2 expression. SCA also showed high efficacy to induce cytochrome c release, activate caspase-9 and -3, and promote late apoptosis of A-549 cells. Therefore, our data suggest that SCA could have an adjuvant therapeutic potential in the treatment of lung cancer. Additionally, we explored that the Akt/mammalian target of rapamycin (mTOR) signaling pathway is involved in SC-, SCA-, SCH-, and SCAH-induced apoptosis of A-549 cells.

Characterization and Antioxidant and Angiotensin I-Converting Enzyme (ACE)-Inhibitory Activities of Gelatin Hydrolysates Prepared from Extrusion-Pretreated Milkfish (Chanos chanos) Scale.

Fish gelatin hydrolysates have been shown to possess various biological activities due to their unique Gly-Pro-Y and Gly-X-Hyp sequences. In the current study, fish gelatin was extracted from non-extruded milkfish scale (FSG1) or extrusion-pretreated milkfish scale (FSG2); extracted gelatins were hydrolyzed with different combinations of Flavourzyme and Alcalase to give four different hydrolysates, namely: FSGH1 (FSG1 hydrolyzed with Flavourzyme), FSGH2 (FSG1 hydrolyzed with Alcalase + Flavourzyme), FSGH3 (FSG2 hydrolyzed with Flavourzyme), and FSGH4 (FSG2 hydrolyzed with Alcalase + Flavourzyme). The extrusion-pretreatment process enhanced the extraction yield of gelatin from fish scale. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) analyses showed the extracts FSG1 and FSG2 possessed characteristics of gelatin. Moreover, the physicochemical characteristics of FSGH1⁻FSGH4 were examined by analyses of their degree of hydrolysis, amino acid composition, UV spectrum, FTIR spectrum, molecular weight, and RP-HPLC profile. Additional biological functional analyses showed that all of the studied gelatin hydrolysates FSGH1⁻FSGH4 possessed antioxidant activity dose-dependently as revealed by DPPH scavenging, ABTS scavenging, and reducing power analyses. In addition, FSGH2 and FSGH4 showed higher angiotensin-I-converting enzyme (ACE)-inhibitory activity as compared to FSGH1 and FSGH3. Taken together, FSGH2 and FSGH4 showed high antioxidant activity and potent anti-ACE activity. Due to the potential antioxidant and antihypertensive properties of FSGH2 and FSGH4, further research is needed to explore their possible use as natural supplementary raw materials in food and nutraceutical products.

Determination of the Bacterial Community of Mustard Pickle Products and Their Microbial and Chemical Qualities.

We assessed the microbial and chemical qualities and microbiomes of 14 mustard pickle products coded sequentially from A to N and sold in traditional Taiwanese markets. The results showed that the aerobic plate count and lactic acid bacteria count of commercially available mustard pickle products were 2.18-4.01 and <1.0-3.77 log CFU/g, respectively. Moreover, no coliform bacteria, Escherichia coli, Staphylococcus aureus, Salmonella spp., or Listeria monocytogenes were detected in any of the samples. Analysis of the chemical quality showed that the sulfite content of all samples exceeded 30 ppm, which is the food additive limit in Taiwan. Furthermore, the mean contents of eight biogenic amines in the mustard pickle product samples were below 48.0 mg/kg. The results of high-throughput sequencing showed that the dominant bacterial genera in sample A were Proteus spp. (25%), Vibrio (25%), and Psychrobacter (10%), in sample C they were Weissella (62%) and Lactobacillus (15%), in sample E it was Lactobacillus (97%), and in sample J it was Companilactobacillus (57%). Mustard pickle product samples from different sources contained different microbiomes. The dominant bacterial family was Lactobacillaceae in all samples except for sample A. In contrast, the microbiome of sample A mainly consisted of Morganellaceae and Vibrionaceae, which may have resulted from environmental contamination during storage and sales. The result of this work suggests it may be necessary to monitor sulfite levels and potential sources of bacterial contamination in mustard pickle products, and to take appropriate measures to rule out any public health risks.

Effect of High-Pressure Processing on the Qualities of Carrot Juice during Cold Storage.

This study examines the impact of blanching (heating at 85 °C for 60 s), high-pressure processing (HPP) (600 MPa, 3 min, 20 °C), and a combination of both blanching and HPP on the microbiological and chemical qualities, colour, and antioxidant properties of carrot juice stored at 4 °C for 15 days. In terms of microbiological quality, the total plate count (TPC), coliform bacteria, and Salmonella spp. rose rapidly in the control group (untreated) as the storage time increased. However, for the blanching group, these values climbed more gradually, surpassing the microbiological limits for juice beverages (TPC < 4 log CFU/mL, Coliform < 10 MPN/mL, and Salmonella spp. negative) on the 9 days of storage. In contrast, TPC, coliforms, and Salmonella spp. were undetectable in the HPP and blanching/HPP samples throughout the storage period. Additionally, as storage time lengthened, the pH, total soluble solids, and Hunter colour values (L, a, b) diminished in the control and blanching groups, whilst titratable acidity and browning degree intensified. However, the HPP and blanching/HPP noticeably delayed these decreases or increases. Moreover, although the total phenolic content and DPPH radical scavenging ability in the HPP samples remained relatively stable during storage and were lower compared to other groups, the ß-carotene content was higher at the end of the storage period. In summary, HPP can effectively deactivate microorganisms in carrot juice, irrespective of whether blanching is applied, and can impede reductions in pH, increases in acidity, and colour changes, ultimately extending the juice's shelf life.

Physicochemical Quality Retention during Cold Storage of Prepackaged Barramundi Meat Processed with a New Microwave-Assisted Induction Heating Technology.

Microwave-assisted induction heating (MAIH) is a composite microwave and induction heating to supply rapid and uniform heating of food. A recent study showed that the optimum MAIH heating condition for barramundi meat was 90 °C/110 s or 70 °C/130 s. This study examines whether the microwave-assisted induction heating (MAIH) technology (at 70 °C for 130 s or 90 °C for 110 s) can more effectively slow down the quality loss of barramundi meat during cold storage than the traditional boiling method (at 90 °C for 150 s). The results show that no microbial growth was observed in the three groups of heated barramundi meat samples during the 60 days of cold storage. However, the MAIH technology slowed down the increase in the total volatile basic nitrogen (TVBN) content more significantly than the boiling method. As the cold storage time increased, though, the L* (lightness), a* (redness), and W (whiteness) values decreased, while the b* (yellowness) and color difference (ΔE) values increased in the three treatment groups. However, the MAIH technology slowed down the decrease in the L*, a*, and W values more significantly, and produced a ΔE value smaller than the boiling method. Moreover, the MAIH technology ensured higher hardness and chewiness of the barramundi meat than the boiling method. Overall, the MAIH technology slowed down the quality loss of the barramundi meat and maintained better color and texture during cold storage.

Replacing the Addition of Sulfite in Mustard Pickle Products by High-Hydrostatic-Pressure Processing to Delay Quality Deterioration during Storage.

This study aimed to assess the use of the high-hydrostatic-pressure (HHP) method (200-600 MPa, 5 min) for bleaching mustard pickle products as an alternative to the conventional method of sulfite addition. The aerobic plate count (APC) and lactic acid bacteria count (LAB) of the samples decreased with the increase in pressure, and the yeast count decreased to no detectable levels. Next, compared with the control group (no high-pressure treatment) the L* (lightness), W (whiteness), ΔE (color difference), and texture (hardness and chewiness) of the HHP-processed samples, which increased significantly with increasing pressure, while the a* (redness) and b* (yellowness) values decreased slightly. This indicates that HHP processing gave the mustard pickle a harder texture and a brighter white color and appearance. Furthermore, when the mustard pickle was treated with HHP 400 and 600 MPa for 5 min and stored at 25 °C for 60 days, it was found that the APC and LAB counts in the HHP-processed group recovered rapidly and did not differ from those in the control group (the non-HHP treated group) but significantly delayed the growth of yeast, the increase in pH value, and total volatile basic nitrogen (TVBN). The high-throughput sequencing (HTS) analysis revealed that the predominant bacterial genera in the non-HHP-treated mustard pickle were Lactiplantibacillus (74%), Lactilactobacillus (12%), and Levilactobacillus (6%); after 60 days of storage, Companilactobacillus (80%) became dominant. However, after 60 days of storage, Lactiplantibacillus (92%) became dominant in the samples processed at 400 MPa, while Levilactobacillus (52%), Pediococcus (17%), and Lactiplantibacillus (17%) became dominant in the samples processed at 600 MPa. This indicated that the HHP treatment changed the lactic acid bacterial flora of the mustard pickle during the storage period. Overall, it is recommended to treat the mustard pickle with HHP above 400 MPa for 5 min to improve its texture and color and delay the deterioration of quality during storage. Therefore, HHP technology has the potential to be developed as a treatment technique to replace the addition of sulfite.

Inactivation Kinetics of Foodborne Pathogens in Carrot Juice by High-Pressure Processing.

In this study, Salmonella Typhimurium, Escherichia coli, and Listeria monocytogenes were separately inoculated in sterilized carrot juice and subjected to various types of high-pressure processing (HPP) at 200-600 MPa for 0.1-15 min to observe the effects of HPP on the inactivation kinetics of foodborne pathogens in carrot juice. The first-order model fits the destruction kinetics of high pressure on foodborne pathogens during the pressure hold period. An increase in pressure from 200 to 600 MPa decreased the decimal reduction time (D values) of S. Typhimurium, E. coli, and L. monocytogenes. Under pressure ≥ 400 MPa, the D values of E. coli were significantly higher than those of S. Typhimurium and L. monocytogenes, indicating that E. coli had greater resistance to high pressures than the others. The Zp values (the pressure range that causes the D values to change by 90%) of E. coli, S. Typhimurium, and L. monocytogenes were 195, 175, and 170 MPa, respectively. These results indicated that L. monocytogenes and E. coli were the most and least sensitive, respectively, to pressure changes. Additionally, the three bacteria were separately inoculated into thermal-sterilized carrot juice and subjected to 200-600 MPa HPP for 3 min. The treated carrot juices were stored at 4 °C for 27 d. Following S. Typhimurium and E. coli inoculation, the bacterial counts of the control and 200 MPa treatments remained the same during the storage duration. However, they decreased for the 300 and 400 MPa treatment groups with increasing storage duration. During the storage period, no bacterial growth was observed in the 500 and 600 MPa treatments. However, the bacterial number for the control and pressure treatment groups increased with prolonged storage duration following inoculation with L. monocytogenes. Therefore, following HPP, residual L. monocytogenes continued growing stably at low temperatures. Overall, HPP could inhibit and delay the growth of S. Typhimurium and E. coli in carrot juice during cold storage, but it was ineffective at inhibiting the growth of L. monocytogenes. There was a risk of foodborne illness despite the low-temperature storage of juice. The innovation of this preliminary study is to find the impact of high pressure on the inactivate kinetics of three food pathogens in carrot juice and its practical application in simulated contaminated juice.

Determining the Optimal Vacuum Frying Conditions for Silver Herring (Spratelloides gracilis) Using the Response Surface Methodology.

Vacuum frying (VF) is a selective technique for producing high-quality fried food that is mostly used on vegetables, fruits, and potato chips. It is rarely applied to the production of aquatic (especially fish) products. The purpose of this study is to explore whether VF technology can be applied to the preparation of dried silver herring products and to obtain the optimal VF conditions. The response surface methodology (RSM) was used to examine the factors affecting the quality of silver herring (Spratelloides gracilis) products after VF, namely temperature (75, 90, and 105 °C), duration (25, 35, and 45 min), and concentration (0, 15, and 30%) of maltose solution used to immerse the samples during pre-processing. The results indicated that VF temperatures had significant impacts on water activity (Aw), moisture content, yield, oil content, lightness (L* value), and colour difference (ÄE). The higher the VF temperature, the lower the Aw, moisture content, yield, and oil content of the product, but the higher the L* value and ΔE. Next, a longer VF duration resulted in higher oil content of the product. Maltose concentration was significantly and positively correlated with the yield and fracturability of the product. RSM analysis indicated that the optimal combination of processing conditions was a VF temperature of 105 °C, VF duration of 25 min, and maltose concentration of 27%. Under these VF conditions, the silver herring products had a moisture content of 3.91%, Aw of 0.198, oil content of 21.69%, L* value of 28.19, ΔE of 27.31, and fracturability of 359 g/s. In summary, vacuum frying technology is suitable for the preparation of dried silver herring products, and this study can provide the optimal processing conditions for seafood processors to obtain better quality.

Extrusion puffing pretreated cereals for rapid production of high-maltose syrup.

In this study, cereals with high starch content, including brown rice, corn, and buckwheat were pretreated by extrusion. The physicochemical properties of extruded-puffed cereals obtained from different extrusion conditions were analyzed herein. The puffed extrudates exhibited lower bulk density, higher water solubility and gelatinization as compared to untreated cereals. The FTIR-ATR results confirmed a decrease in the crystalline structure of extruded-puffed cereals. A higher Vmax/Km value was observed in the enzymatic saccharification of puffed extrudates that significantly improved hydrolysis rate and yield. Finally, the high-maltose syrup was produced via the enzymatic hydrolysis of extruded-puffed cereals at high substrate concentrations (20 %). After hydrolysis for 180 min at an enzyme substrate ratio (E/S ratio) of 0.2, the syrup with dextrose equivalent (DE) value of 63, 62, and 61 were obtained from extruded-puffed brown rice, corn, and buckwheat, respectively. Our results showed the potential of using extruded-puffed cereals for producing high-maltose syrup.

Inhibitory Effects of High-Hydrostatic-Pressure Processing on Growth and Histamine Formation of Histamine-Forming Bacteria in Yellowfin Tuna Meat during Storage.

In the research, we evaluated the effects of high-pressure processing (HPP) on the growth and histamine formation of histamine-forming bacteria (HFB) in yellowfin tuna meat during storage. Tuna meat samples inoculated with the individual HFB species Morganella morganii and Photobacterium phosphoreum were subjected to HPP treatment at 250, 350, 450, and 550 MPa for 5 min, and the changes in bacterial count, total volatile basic nitrogen (TVBN) content, pH, and histamine content during storage at 4 and 15 °C were analyzed. The results indicate that the bacterial counts of the HFB species decreased significantly with increasing pressure, and HFB became undetectable in the samples treated at 450 and 550 MPa. At a storage temperature of 15 °C, the bacterial counts of both HFB species in the control group and samples subjected to HPP treatment at 250 and 350 MPa increased significantly with storage time. The bacterial counts of M. morganii in the samples stored at 4 °C decreased, whereas those of P. phosphoreum increased gradually owing to its psychrophilic nature. HPP treatment (>250 MPa) inhibited the increases in pH and TVBN content of the samples stored at 15 °C and delayed histamine formation in the samples during storage; these effects were more significant as the pressure during HPP treatment was increased.

Extraction, Biochemical Characterization, and Health Effects of Native and Degraded Fucoidans from Sargassum crispifolium.

In the current investigation, a native crude fucoidan (Ex) was extracted from Sargassum crispifolium, pretreated by single-screw extrusion, and two degraded fucoidans, i.e., ExAh (degradation of Ex by ascorbic acid) and ExHp (degradation of Ex by hydrogen peroxide), were obtained. The extrusion pretreatment increased the extraction yield of fucoidan by approximately 1.73-fold as compared to the non-extruded sample. Among Ex, ExAh, and ExHp, their molecular weight and chemical compositions varied, but the structural features were similar. ExHp possessed the greatest antioxidant activities among the extracted fucoidans. According to the outcome, ExAh exhibited the maximum immune promoting effects via enhanced NO, TNF-α, IL-1ß, IL-6, and IL-10 secretion. Thus, both ExHp and ExAh may potentially be used as an effective antioxidant and as immunostimulant agents, which could be of great value in the development of food and nutraceutical products.

Differential Proteomic Analysis of Listeria monocytogenes during High-Pressure Processing.

High-pressure processing (HPP) is a prevailing non-thermal food preservation technology. The inactivation mechanisms of Listeria monocytogenes under HPP at 200 and 400 MPa for 3 min were investigated by label-free quantitative proteomic analysis and functional enrichment analysis in the Kyoto Encyclopedia of Genes and Genomes. HPP treatment at 400 MPa exhibited significant effects on proteins involved in translation, carbon, carbohydrate, lipid and energy metabolism, and peptidoglycan biosynthesis. HPP increased most ribosomal subunits and initiation factors, suggesting it might shift ribosomal biogenesis to translation initiation. However, protein synthesis was impaired by the shortage of proteins responsible for elongation, termination and recycling. HPP stimulated several ATP-dependent Clp proteases, and the global transcriptional regulator Spx, associating with activation of the stress-activated sigma factor Sigma B (σB) and the transcriptional activator positive regulatory factor A (PrfA) regulons. The quantitative proteomics approaches provide fundamental information on L. monocytogenes under different HPP pressures, and provide theoretical support for HPP against Listeriosis illness and for promotion of safer ready-to-eat foods.

Quality Improvement in Mackerel Fillets Caused by Brine Salting Combined with High-Pressure Processing.

The purpose of the study is to investigate the effects of brine salting and high-pressure processing (HPP) on the microbial inactivation and quality parameters of mackerel fillets. Mackerel fillets were immersed in 3% and 9% sodium chloride brine for 90 min at refrigerator temperature, and then treated at 300, 400, 500, and 600 MPa pressure for 5 min. The microbial counts and physicochemical qualities of the fish were examined. In comparison with fish fillets treated with brine or high pressure alone, those treated with the combination of brine salting and HPP showed significantly reduced aerobic plate count (APC) and psychrotrophic bacteria count (PBC). The hardness and chewiness of salt-brined fillets were obviously lower than those of the unsalted fillets under the same pressure condition. Thus, brine salting imparted mackerel fillets a softer texture, which compensated for the HPP-induced increased hardness and chewiness of the fillets. The L* (lightness) and ΔE (colour difference) values of the fillets increased with increasing pressure, with or without brine salting. Conversely, a* (redness) values decreased with increasing pressure. The samples treated with 3% brine in combination with 300 or 400 MPa pressure had a* values similar to those of the samples processed under similar HPP conditions alone but showed lower ΔE values than the other groups. Therefore, as a very high pressure would adversely affect the texture and colour of the fish fillets, this study suggests that immersion in an appropriate brine concentration (3%) and treatment with HPP at 400 MPa for 5 min improved or maintained the colour and texture relatively well and produced a synergistic bactericidal effect.

Preliminary Evaluation of a Novel Microwave-Assisted Induction Heating (MAIH) System on White Shrimp Cooking.

The microwave-assisted induction heating (MAIH) system provides comprehensive heating by combining microwave heating (with 1300 W of power and 2450 MHz of frequency) in the top part and induction heating (with 1800 W of power) in the bottom part. In this study, fresh white shrimps were placed in a sealed crystallized polyethylene terephthalate (CPET) container and heated in the MAIH system at two temperatures (130 and 90 °C) from 60 to 120 s. Afterwards, the shrimp samples were rapidly cooled, and the changes in the shrimp quality, including the appearance, cook loss, aerobic plate count (APC), color values, and texture, during the heating process were analyzed. The results demonstrate that longer heating times decrease the APC levels, but increase the cook loss, color values (lightness, redness, and whiteness), and texture (hardness, cohesiveness and chewiness) of the white shrimp samples. In particular, the white shrimp is fully cooked and gains a completely red appearance, along with no APC detected after heating in the MAIH system at 130 °C for at least 80 s or at 90 °C for at least 100 s. In summary, to achieve a good appearance, no APC detected, and low cook loss, the following heating conditions are recommended for cooking white shrimp in the MAIH system: heating at 130 °C for 80 s or at 90 °C for 100 s. This novel MAIH technology allows food to be heated and sterilized after being packed, thereby eliminating the post-pollution issue. To the best of the authors' knowledge, this is the first study to evaluate the use of MAIH in the application of food processing.

Effect of a Novel Microwave-Assisted Induction Heating (MAIH) Technology on the Quality of Prepackaged Asian Hard Clam (Meretrix lusoria).

The microwave-assisted induction heating (MAIH) method-an emerging thermal technique-was studied to heat the prepackaged raw hard clam (Meretrix lusoria). The cooking effects on microbial and physiochemical qualities of clam were investigated. After the heating of the clam meat samples, the aerobic plate count (APC), psychrotrophic bacteria count (PBC), and total volatile basic nitrogen (TVBN) levels decreased with increasing heating time, but the shucking ratio, area shrinkage, and texture (hardness, cohesiveness, and chewiness) increased. In addition, the L* (lightness) and W (whiteness) of the clam meat samples increased significantly at the beginning of the heating period, whereas they decreased significantly with extended heating time. However, a* (redness) had the opposite trend. This study found that when clams were heated for more than 120 s at 130 °C or 150 s at 90 °C, they displayed obvious shrinking and a yellow-brown appearance, indicating that they are overcooked. After heating by MAIH for at least 110 s at 130 °C or 130 s at 90 °C, the samples were cooked well and gains a completely shucking, along with no microbial count detected. Therefore, the results indicated that the optimum heating conditions for prepackaged hard clams subjected to an MAIH machine were 130 °C for 110 s or 90 °C for 130 s.

Extraction of chitosan from squid pen waste by high hydrostatic pressure: Effects on physicochemical properties and antioxidant activities of chitosan.

Squid pen sample was treated by high hydrostatic pressure (HHP) prior to the extraction of chitosan. The physicochemical and antioxidant activities of the chitosan obtained with HHP (HHP-CS) were compared with chitosan of untreated squid pen sample (UT-CS). The chitosan extraction yield was optimized using response surface methodology, and the optimum condition was achieved at pressure of 500 MPa, extraction time of 10 min, and 1% (w/w) acetate concentration. The maximum yield of chitosan sample from the chitin of squid pens treated by HHP reached 81.9%. Among the process variables, the combined effects of pressure and acetate concentration significantly enhanced the extraction of chitosan from squid pens. The HHP-CS was found to be significantly effective in enhancing the fat binding capacity, water binding capacity, and water solubility index. SEM image analysis suggested that the HHP-CS had a rough surface with high porosity, while UT-CS exhibited a smooth surface. In vitro antioxidant assay suggested that HHP-CS had significantly higher DPPH radical scavenging activity, greater reducing power, and a stronger ferrous ion chelating effect than did UT-CS. Therefore, HHP can be an excellent alternative method for improving the physicochemical properties and antioxidant activities of chitosan from squid pens.