Volatile Base Research Articles

A ratiometric indicator pad utilizing Alz/BRI-PVA for visual assessment of fish freshness

In this study, a novel intelligent water-absorbent cellulose pad with a specified area was developed for the visual and non-destructive monitoring of fish freshness. The pad’s substrate was composed of wood pulp cellulose (WPC), and the specified area contained a ratiometric mixture of brilliant blue (BRI) and alizarin (Alz)., fixed with Polyvinyl alcohol (PVA). During the freshness monitoring process, the Alz/BRI-PVA WPC pad exhibited a color transition from green to brown, followed by a shift to purple-red, corresponding to the increasing levels of total volatile base nitrogen (TVB-N) and total viable count (TVC). After testing, a BRI/Alz ratio of 1:8 was selected as the optimal ratio. Compared to the volatile gas-based sensing tags, the pad developed in this study demonstrated a high sensitivity of 53.4% by interacting with the sample exudate to produce signal changes. This study demonstrates the feasibility of using the developed dual-functional pad for water absorption and freshness indications.

Efficacy Evaluation of Chlorine Dioxide and Hypochlorous Acid as Sanitisers on Quality and Shelf Life of Atlantic Salmon (Salmo salar) Fillets.

Microbial contamination during seafood processing can often lead to a reduction in shelf life and the possibility of food-borne illnesses. Sanitisation with chlorine-based products during seafood processing is therefore sometimes undertaken. This study compared the effects of two sanitisers, chlorine dioxide (ClO2) and hypochlorous acid (HOCl) at their suggested concentration (5 ppm and 10 ppm; 50 ppm and 100 ppm respectively), on physical, chemical, and microbial qualities of Atlantic salmon (Salmo salar) fillets throughout 7 days of simulated retail display refrigeration. Parameters used for assessment included quality index (QI), drip loss, colour, texture, histology, total volatile base nitrogen (TVB-N), lipid oxidation (malonaldehyde, MDA), pH, and total viable count changes. Results indicated that whilst drip loss increased over the storage time, day 4 and 7 drip loss in both sanitisers decreased significantly compared with the control. There was a linear relationship (R > 0.70) between QI and storage time in all treatments, particularly in regard to skin brightness, flesh odour, and gaping parameters, but treatment differences were not present. Texture parameters including gumminess, chewiness, and hardness increased over time in the control whilst both sanitiser treatments seemed to provide protective effects against texture hardening during storage. The observed softening effects from the sanitiser treatments were aligned with microstructural and cytological changes in the histology results, as evidenced by a reduced fibre-fibre adhesion, myodigeneration, and an increase in interfibrillar space over storage time. Colour, especially chroma (C*), was shown to decrease over time in control, whereas insignificant protective effects were observed in both sanitiser treatments at day 7. Irrespective of treatment and storage time, MDA levels exceeded the acceptable limit on all days, whilst TVB-N levels were below the critical limit. Although pH was influenced by treatment and storage time, the pH was within the normal range. Microbiological results showed that with sanitiser addition, TVC was below the permissible level (106 CFU/g) until day 4 but ClO2 ice (5 ppm), ClO2 (10 ppm), and HOCl (100 ppm) treated fillets all exceeded the limit on day 7. The mixed results on the effect of sanitiser addition on fillet quality and shelf life suggested that further investigation on pathogen reduction, sanitiser introductory method, as well as testing the same treatments in low-fat fish models would be recommended.

Development and Application of the Quality Index Method for Ice-Stored King Weakfish (Macrodon ancylodon).

The freshness of raw fish has become one of the industry's and consumers' main concerns regarding quality, safety, and shelf-life estimation. To determine the freshness of the king weakfish (Macrodom ancylodom), the quality index method (QIM) was employed for sensory analyses, along with the assessment of proximate composition, pH, total volatile bases (TVB-N), thiobarbituric acid reactive substances (TBARS), biogenic amines, fatty acids, texture, and microbiological parameters. The results show that the QIM obtained over the storage period exhibited a linear increase, ranging from 2 to 21 demerit points, with a high correlation (R2 = 0.9868) among the data. The microbiological results indicated an increase in the counts of psychrotrophic and mesophilic bacteria throughout the storage period. TVB-N values ranged from 11 to 28 mg/100 g, and TBARS values ranged from 0.235 to 0.298 mg MDA/kg when stored in ice. The presence of putrescine, cadaverine, spermidine, and toxic volatile compounds was a potential indicator of fish freshness. Based on the correlation between the methods considered indicators of freshness and quality, it can be concluded that the king weakfish maintains its commercial stability for up to 11 days when stored in ice.

Innovations in seafood freshness quality: Non-destructive detection of freshness in Litopenaeus vannamei using the YOLO-shrimp model

The relationship between freshness changes and visual images of Litopenaeus vannamei was established based on Sensory Evaluation, Total Volatile Base Nitrogen (TVB-N), Total Viable Count (TVC), and Gray Value during storage at 4 °C. A non-destructive detection system using the advanced YOLO(You Only Look Once)-Shrimp model was developed to evaluate shrimp freshness. The results revealed a gradual increase in freshness indices over time, with the gray value showing strong positive correlations with TVB-N and TVC (0.88 and 0.81). The advanced YOLO-Shrimp model demonstrated notable performance enhancements over the YOLOv8 model, as evidenced by a precision increase of 5.07 %, a recall improvement of 1.58 %, a 3.25 % rise in the F1 score, and a 2.84 % elevation in mAP50. This innovative approach offers substantial potential for enhancing food safety and quality control in the seafood industry.

Effects of Chemically and Green Synthesized Zinc Oxide Nanoparticles on Shelf Life and Sensory Quality of Minced Fish (Pangasius hypophthalmus).

The purpose of this study was to investigate the effect of chemically and green synthesized zinc oxide nanoparticles (ZnO-NPs) on the shelf life and sensory quality of fish meat. In this study, ZnO-NPs were synthesized by employing the colloidal chemistry (CZnO-NPs) and green synthesis (GZnO-NPs) methods, and they were also characterized to assess their morphology. The synthesized ZnO-NPs, ZnO, and zinc acetate (ZnA) were used for the preservation and fortification of fish (Pangasius hypophthalmus) meat at 20 mg/kg of Zn. In a six-day storage study at 4 °C, the fish samples were evaluated for their sensory attributes (color and odor), physicochemical quality (pH and total volatile base nitrogen), oxidative changes (thiobarbituric acid-reactive substances and peroxide value), and microbial loads at 0, 3, and 6 days of storage. The fortification of raw fish with the synthesized CZnO-NPs produced better sensory attributes (color and odor) and maintained a pH non-conducive to microbial growth throughout the entire storage period compared with the control, ZnO, and ZnA-fortified samples. The GZnO-NPs largely did not provide any added advantage over CZnO-NPs but sometimes responded better than the control, ZnO, and ZnA samples. Oxidative status and total volatile base nitrogen were lower for CZnO-NPs in refrigerated fish compared with the other treatments. The ZnO-NP-fortified fish had the lowest counts of total viable bacteria, coliforms, Staphylococcus spp., and Vibrio spp. Hence, the fortification of fish with synthesized CZnO-NPs is promising as a food additive to reduce microbial spoilage and lipid peroxidation of fish in storage.

The Application of Organic and Inorganic Nanoparticles Incorporated in Edible Coatings and Their Effect on the Physicochemical and Microbiological Properties of Seafood

Recent bibliographic research highlights the innovative application of organic and inorganic nanoparticles in edible coatings for seafood preservation. Given the high susceptibility of seafood to spoilage, incorporating nanoparticles into coatings presents a promising solution. These nanoparticles possess significant antioxidant and antimicrobial properties, which contribute to maintaining the quality and extending the shelf life of seafood products. This study reviews various materials and synthesis techniques for nanoparticles, assessing their characteristics and suitability for food applications. It emphasizes the role of nanotechnology in enhancing the mechanical properties of biopolymer-based coatings, which are biodegradable and non-toxic, thus promoting environmental sustainability. The findings indicate that nanoparticle-infused coatings effectively improve the physicochemical properties of seafood, such as pH stabilization and the reduction in total nitrogenous volatile bases, while also inhibiting microbial growth. This multifaceted approach not only addresses food waste and safety concerns but also supports the fishing industry by enhancing product quality. Overall, this research underscores the potential of nanoparticle coatings as a viable strategy for seafood preservation, paving the way for future innovations in sustainable food packaging solutions.

Encapsulation of lemongrass essential oil by bilayer liposomes based on pectin, gum Arabic, and carrageenan: Characterization and application in chicken meat preservation.

The volatile characteristics of lemongrass essential oil (LO) have seriously hindered its further application, and encapsulation it with multilayer modified liposomes may be an effective strategy to improve this dilemma. This study selected chitosan (CH) and three anionic polymers, pectin (P) / gum arabic (GA) / carrageenan (C), as the first and second coating polymers to modify nano liposomes (NL) by layer-by-layer electrostatic deposition, obtaining three bilayer liposomes, P-CH-NL, GA-CH-NL, and C-CH-NL as high-quality stabilized carriers of LO. The bilayer liposomes showed a dense membrane structure ranging from 110 to 150nm uniformly, with good antioxidant properties. All bilayer liposomes had good stability during 28-day storage at 4°C, while C-CH-NL performed relatively better inferred by smaller changes of size, PDI and Zeta potential. The total volatile base nitrogen (TVB-N) values of fresh chicken meat and a total number of bacterial colonies (TBC) experiments showed that GA-CH-NL and C-CH-NL could better retard the increase of volatile salt base nitrogen. All bilayer liposomes could delay the time for the total bacterial count to exceed 6 log CFU/g (from 7days to 10 / 12days). Therefore, the bilayer liposomes P-CH-NL, GA-CH-NL, and C-CH-NL may be promising natural preservatives for food products.

Anthocyanin modified by chondroitin sulphate and tannic acid improved the quality-indicating properties of gelatin-based intelligent film

A highly pH-responsive gelatin film incorporating purple cabbage anthocyanin (PCA) and chondroitin sulphate (CS)/tannic acid (TA) was developed. Co-pigmentation of PCA via CS/TA improved its photothermal stability and visibility of color change in gelatin film. The morphological and structural properties of CS-PCA and TA-PCA films revealed that a more stable network was formed as new hydrogen bonds were generated by the co-pigmentation. Meanwhile, the co-pigmentation improved film's mechanical and hydrophobic properties, expressed as higher tensile strength (16.65 and 17.97 Mpa) and lower water vapor permeability (1.45 and 1.41) in CS-PCA and TA-PCA films, compared to PCA film. CS-PCA and TA-PCA films showed distinct color transitions for chilled fish fillets during storage. Total color difference (ΔE) of CS-PCA and TA-PCA films correlated well with the deterioration indexes of total volatile base nitrogen (TVB-N). All the results provided a novel pH-sensitive intelligent packaging strategy by co-pigmenting CS/TA with PCA for freshness monitoring.

Yield and physical-chemical quality of mechanically separated tilapia meat in different weight classes

Due to heterogeneous growth and reproductive precocity, many tilapia do not reach the ideal size for commercialization and are discarded. Despite this, they are characterized as a high quality raw material and have the potential to be used in human food by obtaining mechanically separated meat (MSM). This research aimed to evaluate the yield and quality of MSM from tilapia in different weight classes, outside the commercial size. Animals were obtained from a commercial farm and transported to the laboratory in insulated boxes. They were then washed, weighed, graded, and eviscerated for the production of MSM. The weight classes studied were: A (≥ 50 g < 80 g), B (≥ 80 g and < 110 g), C (≥ 110 g and < 140 g) and D (≥ 140 g and < 170 g). Carcass yield and DMI, physicochemical, calcium, water activity, water retention capacity and fatty acid profile analyses were performed. After 90 days of storage (-18oC), total volatile bases, lipid oxidation and pH of MSM were determined. The highest carcass yield was obtained in weight class D. This variation can be attributed to the difference in size and weight of the fish in both classes. There was no significant difference in MSM performance between weight classes. Proteins were not affected by weight differences, and lipid content increased with fish size, with an inverse relationship with moisture and ash. The water activity values of tilapia MSM did not show significant differences. In the analysis of water retention capacity, the classes showed high retention with a significant difference, in which class B (45.2%) obtained the highest average WHC, while C (30.8%) presented the lowest result. Regarding the results obtained for calcium, it was observed that class A (≥ 50 < 80g) obtained the highest result (1.22%), significantly different from the others. In this study, no significant differences in TBARS and BVT values were observed between different weight classes. Differences in pH were observed among the weight classes, but all were within the regulatory limits. The main fatty acids found in MSM were palmitic acid (C16:0) (31.63 to 37.29%), oleic acid (25.33 to 30.14%), stearic acid (C18:0) (7. 10 to 10.31%), linoleic acid (C18:2n-6) (8.19 to 14.46%), palmitoleic acid (C16:1) (31.63 to 37.29%), and margaric acid (C17:0) (1.14 to 2.27%). MSM from tilapia with low commercial weight showed satisfactory yield in all weight classes and physicochemical quality in compliance with accepted standards after 90 days of storage.

Preparation and properties of PCL coaxial electrospinning films with shell loaded with CEO and core coated LEO nanoemulsions

During storage and transportation, the reduction of microbial contamination and management of the exudation of fluids from the fish can effectively mitigate spoilage and degradation of fish fillets. In this work, the coaxial electrospinning films loaded with natural plant preservatives, namely laurel essential oil (LEO) and clove essential oil (CEO), were prepared by the coaxial electrospinning method synergistic with nanoemulsion techniques, and the hydrophilic preservation pads were prepared. The morphology of the film fiber is clear, without beads or damage, with fiber diameters falling within the 230–260 nm range. It has a distinct core–shell structure, exceptional thermal stability, and strong antibacterial and antioxidant properties. The core–shell structure of the fiber subtly regulates the release of preservatives and significantly improves the utilization efficiency. At the same time, the synergistic use of two essential oils can reduce the amount while amplifying their effectiveness. The pads significantly slowed down the increase of key indicators of spoilage, such as total viable count (TVC), pH, thiobarbituric acid reactive substances (TBA), and total volatile base nitrogen (TVB-N), during the storage of the fish fillets. Furthermore, the pads effectively slowed down the decline in water-holding capacity, the deterioration of textural qualities, and the negative changes in the microstructure of the fish muscle. Ultimately, the pads notably delayed the spoilage of fish fillets, extending their shelf life from 5 d to 9 d. The efficient utilization of biological preservatives in this film can provide technical support for the development of food preservation materials.

Designing the pH-sensitive indicator based on starch nanoparticle with bromocresol green for monitoring meat spoilage

ABSTRACT The starch nanoparticle, combined with bromocresol green (BCG), served as a pH-sensitive indicator to monitor meat quality throughout an 8-day refrigerated storage period. The meat samples were sealed in package which the pH-sensitive indicator attached to the interior part of packaging lid. The changes in meat quality were evaluated by total volatile base nitrogen (TVBN), pH, total viable count (TVC), sensory analysis, and color in interval of 0, 3, 5, 7, and 8-days storage at 4°C. Initial TVBN values were recorded at 19.6 mg/100 g, increased to 26.6 mg/100 g by the end of storage period. The pH value was significantly increased after 8 days storage at 4°C. The observed color variation in the indicator from yellow to blue was attributed to the concurrent increases in TVBN, TVC, and pH. The indicator color changes had significant correlation with analyzed chemical quality of stored meat. Therefore, the designed BCG pH-sensitive indicator could be effective in monitoring the meat spoilage during storage.

Role of the intestines on the muscle quality of Pacific white shrimp (Litopenaeus vannamei) during chilled storage: Physicochemical and label-free–based peptidomics analyses

The effect of shrimp deveining on the quality of Pacific white shrimp muscle was investigated by analyzing the protein degradation during chilled storage via physicochemical and label-free peptidomics analyses. In this study, shrimp with intact intestines were in the control group (CS), while deveined shrimp (DS) were in the treatment group. The total viability count (TVC), total volatile base nitrogen (TVB-N) content, and trichloroacetic acid (TCA)-soluble peptide content in all of the shrimp groups gradually increased with prolonged chilled storage. However, in the later stages of chilled storage, the DS samples exhibited significantly lower TVB-N, total bacterial, and TCA-soluble peptide contents than the CS samples, indicating that deveining treatment effectively prolonged shrimp quality. The peptidomics analysis revealed varying degrees of protein hydrolysis in the DS and CS samples during chilled storage. A total of 396 differentially abundant peptides (DAPs) were identified in the DS compared with the CS, comprising 98 upregulated and 298 downregulated segments. This suggests that the removal of the intestine effectively inhibits protein hydrolysis. Gene ontology (GO) analysis suggested that the DAPs were mainly involved in catalytic activity, binding, and metabolic processes. The cluster of orthologous groups of protein (COG) analysis showed that the cytoskeleton dynamics of the muscle proteins underwent considerable alterations influenced by the shrimp's intestines during chilled storage.

Study on VOCs of Fishmeal during Storage Based on HS-SPME-GC-MS.

Fishmeal is widely used in the feed industry as the main protein material. The freshness grade directly affects the quality of the fishmeal. During the storage of fishmeal, the odor would change accordingly as the freshness grades decreased. To study the characteristic volatile organic compounds (VOCs) of fishmeal, stored at 25 °C and 80%RH with different freshness grades, headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze. The single-factor test was chosen for 50/30 μm divinylbenzene/carboxe/polydimethylsiloxane (DVB/CAR/PDMS) fiber. The equilibration time of 24 min, the extraction time of 60 min, the extraction temperature of 87 °C, and the addition of a saturated saline volume of 4 mL were determined by Box-Behnken design. There were 15 common VOCs detected during storage, the relative contents of acids increased significantly, ketones, aldehydes, esters, and nitrogen-containing compounds increased, and aromatic compounds and alcohols decreased. Combined with freshness indexes, volatile base nitrogen (VBN) and acid value (AV), hexadecanoic acid, tetradecanoic acid, methyl (Z)-N-hydroxybenzenecarboximidate, (Z)-hexadec-9-enoic acid, 6-ethoxy-2,2,4-trimethyl-3,4-dihydro-1H-quinoline, octadecanal, and [(Z)-octadec-9-enyl] acetate were determined as the characteristic VOCs based on the PLS-DA model. This study may provide data support for the development of fishmeal freshness-detecting instruments.

Effect of lemon juice on the chemical and microbiological quality of rainbow trout (Oncorhynchus mykiss) under refrigerated storage

<p>In recent years, there has been an increasing interest in using food additives from natural sources to improve taste, texture and extend the shelf-life of foodstuffs. The aim of this study was to examine the quality changes in trout treated with lemon juice for 21 days. Fish were divided into T0, T1, T2 and T3 and treated with 0, 1%, 2% and 3% lemon juice respectively. The lowest pH was found in T3 followed by T2, T1 and T0. A significant difference in total volatile base nitrogen (TVBN), peroxide value (PV) and free fatty acid (FFA) was observed between the control and treatments, with the lowest increase in T3 followed by T2. Total plate count (TPC) crossed the limit in T2 and T3 on the 21st day, whereas in control and T1, the permissible limit crossed on the 12th and 18th days respectively. The sensory panel rejected the control on the 12th day and T1 and T3 on the 18th day; however, T2 remained acceptable till the 21st day, thus showing the promising effect of lemon juice on the quality of trout fillet and thereby increasing the shelf-life of the product by nine days.<strong></strong></p>

The Effect of High Intensity Ultrasound on the Quality and Shelf Life of Tilapia (Oreochromis niloticus) Muscle

It has been documented that the shelf life of fishery products is extremely reduced due to microbial development and its endogenous biochemistry. For this reason, food technologists around the world are researching how to reduce the main processes that lead to spoilage. Recently, high-intensity ultrasound (HIU) has had different applications in the food industry because the cavitation effect can inhibit or reduce microbial development as well as cause conformational changes in muscle enzymes. Therefore, in this study, HIU was applied for 30, 60, and 90 min to the tilapia (Oreochromis niloticus) fillet, and subsequently, it was stored on ice for 20 days. During this period, samples were taken every 5 days (day 0, 5, 10, 15, and 20), and moisture content, pH, total volatile base (TVB-N), non-protein nitrogen (NPN), texture, electrophoresis, color, and microbiological analyses (mesophiles and psychrophiles) were determined. No significant changes (p ≥ 0.05) were observed in the moisture content, pH, and the L* parameter, while a significant decrease (p < 0.05) in TVB-N (from 29.67 to 15.09), NPN (from 0.39 to 0.27%), and texture (from 4.88 to 2.69 N) were found. On the other hand, an increase (p < 0.05) in a* (from 2.02 to 4.27) and b* (from 10.66 to 12.45) parameters, as well as total mesophile count (from 2.48 to 6.52 log CFU/g) were detected due to the application of ultrasound. The results suggest that the application of this treatment represents a viable alternative to increase the shelf life and quality of tilapia fillets stored on ice.

An antibacterial film using κ-carrageenan loaded with benzyl isothiocyanate nanoemulsion: Characterization and application in beef preservation

Benzyl isothiocyanate (BITC) is a naturally active bacteriostatic substance and κ-carrageenan (KC) is a good film-forming substrate. In the present study, a nanoemulsion incorporating BITC was fabricated with a particle size of 224.1 nm and an encapsulation efficiency of 69.2 %. Subsequently, the acquired BITC nanoemulsion (BITC-NE) was incorporated into the KC-based film, and the light transmittance of the prepared composite films was lower than that of the pure KC film. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that BITC-NE was compatible with the KC matrix. BITC-NE incorporation enhanced the tensile strength of the KC-based films by 33.7 %, decreased the elongation at break by 33.8 %, decreased the water vapor permeability by 60.1 %, increased the maximum thermal degradation temperature by 48.8 %, and decreased the oxygen permeability by 42 % (p < 0.05). Furthermore, the composite films showed enhanced antimicrobial activity against Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas fluorescens. The developed KC-based composite films were applied to wrap raw beef, which significantly delayed the increase in total viable count, total volatile base nitrogen content, and thiobarbituric acid reactive substances, and prolonged the shelf-life of the raw beef by up to 10 days. These results indicated that the composite films prepared by incorporating BITC nanoemulsions into KC matrices have great antimicrobial application potential.

Effects of slightly acidic electrolyzed water and ginger (Zingiber officinale Roscoe) juice on the quality and myofibrillar protein structure of silver carp (Hypophthalmichthys molitrix) fillets during cold storage

This study aimed to investigate the effects of slightly acidic electrolyzed water (SAEW) pretreatment combined with ginger (Zingiber officinale Roscoe) juice (GJ) on the quality, sensory characteristics, and myofibrillar protein structure of silver carp (Hypophthalmichthys molitrix). The results revealed that the SAEW-GJ delayed microbial spoilage by reducing the total viable counts and Pseudomonas spp. Moreover, the freshness of silver carp fillets was maintained by maintaining lower total volatile base nitrogen (TVB-N), ATP-related compounds, and free amino acids (FAAs). SAEW-GJ delayed myofibrillar protein oxidations by inhibiting the generation of carbonyl groups and maintaining a higher Ca2+-ATPase activity and sulfhydryl content. We also observed that SAEW-GJ treatment maintained myofibrillar organized secondary structure by keeping higher α-helix content and stabilized tertiary structure during cold storage. These results suggested that the SAEW-GJ could be used to enhance the quality of silver carp and prolong the shelf life by at least 6 days during cold storage.

The Impact of Chlorella vulgaris Fortification on the Nutritional Composition and Quality Characteristics of Beef Burgers.

Chlorella vulgaris (C.V) is known for its high protein and nutrient contents and has been touted as a potential functional ingredient in food products. For this study, beef burgers were formulated with varying levels of Chlorella vulgaris fortification (0%, 0.5%, 1%, and 1.5% by weight). The nutritional composition, including proximate analysis and mineral content, was determined for each treatment group. The quality characteristics evaluated included thiobarbituric acid (TBA), total volatile base nitrogen (TVBN), pH, and total acidity. The study included extracting the active substances from Chlorella vulgaris using three solvents, 50% ethanol, 95% ethanol, and water, to evaluate the effect on the antimicrobial and antioxidant activity. The results showed that the water extract had the highest total phenolic content (183.5 mg gallic acid equivalent per gram) and the highest flavonoid content (54 mg quercetin per gram). The aqueous extract had the highest content of total antioxidants, followed by the 95% ethanol and 50% ethanol extracts. Meanwhile, the 50% ethanol extract showed the best antimicrobial activity, while the aqueous extract had less of an effect on Gram-positive bacteria and no effect on E. coli. For the burger treatments, at the end of the storage period, it was observed that the microbial load of the treatments decreased compared to the control, and there was a high stability in the total volatile base nitrogen (TVBN) values for the treatments compared to the control, reaching a value of 22.4 at month 5, which is well above the acceptable limit, indicating spoilage. The pH values were higher for all of the treatments, with a lower total acidity for all of the treatments compared to the control. In conclusion, utilizing Chlorella vulgaris algae as a natural preservative to extend the freshness of burgers is a sustainable and innovative approach to food preservation. By harnessing the power of this green superfood, we not only enhance the shelf life of our food products but also contribute to a healthier and more environmentally friendly food industry.

Effects of chitosan-gentianic acid derivatives on the quality and shelf life of seabass (Lateolabrax maculatus) during refrigerated storage

Chitosan is a natural polymer material with antibacterial, biodegradable and biocompatibility. At present, the research is mainly to enhance the antibacterial and antioxidant activity of chitosan by grafting with phenolic acids to further expand its application in food. In this study, the effect of chitosan-g-gentisic acid graft copolymer (CS-g-GA) on the shelf life of refrigerated seabass (Lateolabrax maculatus) was investigated. The results of microbial analysis demonstrated that GA and CS-g-GA treatment could effectively inhibit the growth of microorganisms. In addition, physicochemical analysis showed that GA and CS-g-GA treatment could reduce the increase of pH value, thiobarbituric acid reactive substances (TBARS), total volatile base nitrogen (TVB-N) and K-value, delay water loss, maintain texture and color, and postpone the decrease of sensory score. Compared with the control sample, CS-g-GA could keep the quality of Lateolabrax japonicus and extend its shelf-life for another 9 days. In summary, CS-g-GA has good application and development prospects for the preservation of seabass.

Effects of different power multi-frequency ultrasound-assisted thawing on the quality characteristics and protein stability of large yellow croaker (Larimichthys crocea)

This study investigated the impact of multi-frequency ultrasound-assisted (20/28/40 kHz) thawing (MUAT) at different power levels (195, 220, 245, and 270 W, respectively) on the flesh quality and protein stability of large yellow croakers. Compared with flowing water thawing (FWT) and the other MUAT sample, flesh quality results indicated that the MUAT-220 W significantly reduced (p < 0.05) thawing loss, total volatile base nitrogen (TVB-N), total free amino acids (FAAs) and thiobarbituric acid reactive substances (TBARS). Low-field nuclear magnetic resonance (LF-NMR) spectroscopy indicated that MUAT-220 W samples had higher immobilized water content and lower free water content. In addition, the MUAT-220 W sample contained higher sulfhydryl and lower carbonyl contents compared to the FWT sample. Secondary and tertiary structural results of myofibrillar proteins (MPs) showed that MUAT-220 W significantly reduced thawing damage to MPs. Therefore, MUAT-220 W improved the quality and protein stability of the large yellow croaker during the defrosting process.