Spoilage Indicators Research Articles

Chilled Pacu (Piaractus mesopotamicus) fillets: Modeling Pseudomonas spp. and psychrotrophic bacteria growth and monitoring spoilage indicators by 1H NMR and GC–MS during storage

This study aimed to assess the growth of Pseudomonas spp. and psychrotrophic bacteria in chilled Pacu (Piaractus mesopotamicus), a native South American fish, stored under chilling conditions (0 to 10 °C) through the use of predictive models under isothermal and non-isothermal conditions. Growth kinetic parameters, maximum growth rate (μmax, 1/h), lag time (tLag, h), and (Nmax, Log10 CFU/g) were estimated using the Baranyi and Roberts microbial growth model. Both kinetic parameters, growth rate and lag time, were significantly influenced by temperature (P < 0.05). The square root secondary model was used to describe the bacteria growth as a function of temperature. Secondary models, √μ = 0.016 (T + 10.13) and √μ =0.017 (T + 9.91) presented a linear correlation with R2 values >0.97 and were further validated under non-isothermal conditions. The model's performance was considered acceptable to predict the growth of Pseudomonas spp. and psychrotrophic bacteria in refrigerated Pacu fillets with bias and accuracy factors between 1.24 and 1.49 (fail-safe) and 1.45–1.49, respectively. Fish biomarkers and spoilage indicators were assessed during storage at 0, 4, and 10 °C. Volatile organic compounds, VOCs (1-hexanol, nonanal, octenol, and indicators 2-ethyl-1-hexanol) showed different behavior with storage time (P > 0.05). 1H NMR analysis confirmed increased enzymatic and microbial activity in Pacu fillets stored at 10 °C compared to 0 °C. The developed and validated models obtained in this study can be used as a tool for decision-making on the shelf-life and quality of refrigerated Pacu fillets stored under dynamic conditions from 0 to 10 °C.

Exploiting the microbiota of organic and inorganic acid-treated raw poultry products to improve shelf-life.

Targeted amplicon sequencing of the 16S rRNA delineates the complex microbial interactions that occur during food spoilage, providing a tool to intensively screen microbiota response to antimicrobial processing aids and interventions. The current research determines the microbiota and spoilage indicator (total aerobes and lactic acid bacteria; LAB) response to inorganic and organic antimicrobial intervention use on the shelf-life of fresh, never-frozen, skin-on, bone-in chicken wings. Wings (n=200) were sourced from local processor and either not treated (NT) or treated with 15-s dips of tap water (TW), organic (peracetic acid; PAA), inorganic acids (sodium bisulfate; SBS), and their combination (SBS + PAA). Wings were stored (4°C) and rinsed in neutralizing Buffered Peptone Water (BPW) for 1 min on d 0, 7, 14, and 21 post-treatment. Spoilage indicators, aerobic mesophiles and LAB, were quantified from rinsates. Genomic DNA of d 14 and 21 rinsates were extracted, and V4 of 16S rRNA gene was sequenced. Sequences were analyzed using QIIME2.2019.7. APC and LAB counts were reported as Log10 CFU/g of chicken and analyzed in R Studio as a General Linear Model using ANOVA. Pairwise differences were determined using Tukey's HSD (P£0.05). Spoilage was indicated for all products by day 21 according to APC counts (>7 Log10 CFU/g); however, wings treated with SBS and SBS + PAA demonstrated a 7-day extended shelf-life compared to those treated with NT, TW, or PAA. The interaction of treatment and time impacted the microbial diversity and composition (p < 0.05), with those treated with SBS having a lower richness and evenness compared to those treated with the controls (NT and TW; p < 0.05, Q < 0.05). On d 14, those treated with SBS and SBS + PAA had lower relative abundance of typical spoilage population while having a greater relative abundance of Bacillus spp. (~70 and 50% of population; ANCOM p < 0.05). By d 21, the Bacillus spp. populations decreased below 10% of the population among those treated with SBS and SBS + PAA. Therefore, there are differential effects on the microbial community depending on the chemical intervention used with organic and inorganic acids, impacting the microbial ecology differently.

Biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/curcumin composite film as a smart indicator of food spoilage

Due to the global issue of food wastage, smart packaging technologies have been garnering growing attention in the food industry. These technologies provide comprehensive information throughout the food distribution process, including maintaining freshness, regulating temperature and humidity of food products. In this study, we developed an intelligent indicator film composed of microbial aliphatic polyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHB), and curcumin, a natural pH-sensitive dye with antioxidant and antibacterial properties. The PHBC displayed various beneficial properties including UV protection and curcumin release, as well as antioxidant and antibacterial activities. In addition, the PHBC exhibited excellent colorimetric sensitivity to volatile nitrogen compounds generated during the spoilage of protein-rich foods like meat and seafood. The PHBC intelligent indicator film could detect the food freshness through colorimetric changes caused by volatile alkaline nitrogen compounds generated during food storage, confirming that it can be applied as an intelligent indicator for detecting food spoilage.

Sustained-release film prepared by incorporation of cinnamon essential oil: Physicochemical properties and application in the preservation of mushroom (Agaricus bisporus)

The chitosan/zein/cinnamon essential oil (CEO) sustained-release active film was developed. The rheological properties of film-forming solutions (FFS) and the physicochemical properties of films were investigated. The effects of active film on mushroom quality were evaluated. When CEO and Tween 80 were mixed in a ratio of 1:3, the particle size of the essential oil emulsion was the smallest and the distribution was more uniform. Rheological analysis showed that FFS was non-Newtonian fluids. With the increase of CEO, FFS became more viscous and the intermolecular entanglement was enhanced. CEO improved the UV-blocking activity and hydrophobicity of the composite film. The tensile strength increased from 16.54 to 21.22 MPa. Moreover, the active film inhibited the growth of Pseudomonas tolaasii. And the antioxidant property of film was improved with the addition of CEO. The SEM images, FTIR, and XRD spectra displayed that CEO had good compatibility with film matrix. TGA demonstrated the thermal stability of film was enhanced. In addition, the release of CEO in four simulants followed Fick's law of molecular diffusion. Compared with the control group and C/Z group, the L* value of mushrooms treated with C/Z-CEO0.6% films could be kept above 80 during storage, and the spoilage index of mushrooms was lower (31.2%). Mushroom treated with C/Z-CEO0.6% films showed the lowest weight loss and the highest firmness. All in all, the chitosan/zein-based active films containing CEO, as a new food packaging ma restrainterial, will play a good role in retaining the quality of food.

Anti-bacterial films developed by incorporating shikonin extracted from radix lithospermi and nano-ZnO into chitosan/polyvinyl alcohol for visual monitoring of shrimp freshness

In recent years, the utilization of smart colorimetric packaging films for monitoring food freshness has garnered significant concentration. However, their limited tensile strength, hydrophobicity, antioxidant, and antibacterial properties have been substantial barriers to widespread adoption. In this study, we harnessed the potential of biodegradable materials, specifically chitosan/polyvinyl alcohol, alongside shikonin extracted from Radix Lithospermi and ZnO nanoparticles, to create a novel colorimetric sensing film. This film boasts an impressive tensile strength of 82.36 ± 2.13 MPa, enhanced hydrophobic characteristics (exemplified by a final contact angle of 99.81°), and outstanding antioxidant and antibacterial properties. It is designed for real-time monitoring of shrimp freshness. Additionally, we verified the effectiveness of this sensing film in detecting shrimp freshness across varying temperature conditions, namely 25 °C and 4 °C was validated through the measurement of total volatile basic nitrogen (TVB-N). Visual inspection unequivocally revealed a transition in color from dark red to purple-light blue and finally to dark bluish providing a clear indication of shrimp spoilage, which demonstrated a strong correlation with the TVB-N content in shrimp measured through standard laboratory procedures. The colorimetric sensing film developed in this study holds great promise for creating smart labels with exceptional antioxidant and antibacterial properties, tailored for visual freshness monitoring of shrimp.

Carrageenan-based active and intelligent packaging films integrated with anthocyanin and TiO2-doped carbon dots derived from sweet potato peels

Carrageenan-based sustainable active and pH-dependent color-changing composite films were fabricated by blending anthocyanin extracted from sweet potato peel (SPA) with TiO2-doped carbon dots (Ti-CDs) prepared using the biowaste of SPA extraction. The SPA and Ti-CDs were compatible with the carrageenan matrix and were uniformly dispersed in the used polymer to form a homogeneous film with increased mechanical properties. The composite film added with SPA and 3 wt% Ti-CD showed 100 % UV protection, superb antioxidant (100 % DPPH and ABTS scavenging assay), and potent antibacterial activity (complete eradication of foodborne L.monocytogenes and E. coli strains after 3 h incubation). Additionally, the composite films showed distinguishable colorimetric responses to pH 7–12 buffers and volatile ammonia. The intelligent sensing ability of the composite film was assessed through shrimp freshness monitoring, and the film's hue shifted from pink (fresh shrimp) to yellow/brown (inedible shrimp) during storage. Shrimp packaging studies have shown that composite films retard the rate of food quality change during storage and are a good indicator of shrimp spoilage. Therefore, the designed film is expected to have high applicability as a chip, and quick on-site sensor that detects seafood quality in real-time, and a highly effective multifunctional film for better product quality preservation.

Monitoring the prevalence of Pseudomonas fluorescens as a spoilage indicator in cow raw milk, teat surfaces, and milk tanks.

Milk and its products are very sensitive to spoilage if they are kept under unsuitable conditions which may provide favorable circumstances for the growth of specific spoilage organisms, Pseudomonas fluorescens accounted as the most dominant indicator for milk spoilage. This study highlights monitoring the prevalence of P. fluorescens as a spoilage indicator organism in cow raw milk and its contact surfaces represented by teat surfaces and milk tanks in Nineveh province. A total of 150 samples from cows' raw milk, teat surfaces, and milk tank swabs were collected from different locations in Nineveh province from October 2023 till February 2024. The Pseudomonas fluorescens were detected by using conventional cultivation methods supported by molecular detection of the target pathogen using the polymerase chain reaction technique. Out of 150 samples, 48 (32%) were positive for the prevalence of P. fluorescens by traditional methods, and 39 (26%) were positive using PCR assay according to the 16SPflu gene yielded a band at 850 bp. The P. fluorescens was recovered at 19 (38%) from raw milk. Teat surfaces revealed a higher isolation rate 11 (22%) compared to milk tanks 9 (18%). The mean counts of Pseudomonas in cows raw milk revealed 4.38, 6.29, and 7.37 log CFU/ml for the 0, 3, and 6 days of storage at chilling temperature. Results of DNA sequencing of the 16SrRNA gene revealed 12 strains recorded in the GenBank nucleotide sequence database. Our results shed light on the risk of P. fluorescens prevalence as a spoilage indicator in raw milk and surrounding surfaces which is inevitable to apply hygienic procedures during milk collecting, processing, and preservation to increase the shelf life of the products and ensure milk safety and consumer health.

Applications of chemically modified screen-printed electrodes in food analysis and quality monitoring: a review.

Food analysis and food quality monitoring are vital aspects of the food industry, ensuring the safety and authenticity of various food products, from packaged goods to fast food. In this comprehensive review, we explore the applications of chemically modified Screen-Printed Electrodes (SPEs) in these critical domains. SPEs have become extremely useful devices for ensuring food safety and quality assessment because of their adaptability, affordability, and convenience of use. The Introduction opens the evaluation, that covers a wide spectrum of foods, encompassing packaged, junk food, and food quality concerns. This sets the stage for a detailed exploration of chemically modified SPEs, including their nature, types, utilization, and the advantages they offer in the context of food analysis. Subsequently, the review delves into the multitude applications of SPEs in food analysis, ranging from the detection of microorganisms such as bacteria and fungi, which are significant indicators of food spoilage and safety, to the identification of pesticide residues, food colorants, chemicals, toxins, and antibiotics. Furthermore, chemically modified SPEs have proven to be invaluable in the quantification of metal ions and vitamins in various food matrices, shedding light on nutritional content and quality.

Functional approach to D-fortification of sunflower oil as a factor of nutritional compensation of vitamin deficiency and immunoprophylaxis

In modern conditions of the spread of new strains of microorganisms, along with sanitary and hygienic issues of prevention, measures aimed at immunoprotection play an important role. Insufficient micronutrient supply of vitamin D contributes to a high susceptibility of a person to an infectious agent. Insufficient supply of vitamin D contributes to a high human susceptibility to an infectious agent. Adequate compensation for chronic deficiency of fat-soluble vitamin D in food belongs to a promising field of nutritionology. In the structure of oilseed production of Russian farmers, about 60% is occupied by sunflower oil, which practically lacks vitamin D. The development of fortified sunflower oil that compensates for this need solves a two-pronged task: as a preventive measure and as a biologically valuable food product. According to the research results, it has been established that the fortification of unrefined sunflower oil with the addition of 0.04... 0.20 ml of vitamin D3 oil solution with an activity of 50,000 M.E. provides coverage of 10-50% of the daily requirement for vitamin D3. In the samples of unpacked unrefined sunflower oil, the indicators of oxidative spoilage during storage up to 60 days corresponded to the normalized requirements for premium vegetable oil with lower indicators with an increase in the amount of vitamin D3 oil solution added.

Changes in the Microbiota from Fresh to Spoiled Meat, Determined by Culture and 16S rRNA Analysis

Growth of meat microbiota usually results in spoilage of meat that can be perceived by consumers due to sensory changes. However, a high bacterial load does not necessarily result in sensory deviation of meat; nevertheless, this meat is considered unfit for human consumption. Therefore, the aims of this study were to investigate changes in the microbiota from fresh to spoiled meat and whether the proportions of certain bacteria can probably be used to indicate the hygiene status of meat. For this purpose, 12 fresh pork samples were divided into two groups, and simultaneously aerobically stored at 4°C and 22°C. At each time-temperature point (fresh meat, days 6, 13, and 20 at 4°C, and days 1, 2, 3, and 6 at 22°C), 12 meat subsamples were investigated. Sequences obtained from next-generation sequencing (NGS) were further analyzed down to species level. Plate counting of six bacterial groups and NGS results showed that Pseudomonas spp. and lactic acid bacteria (LAB) were found in a high proportion in all stored meat samples and can therefore be considered as important “spoilage indicator bacteria”. On the contrary, sequences belonging to Staphylococcus epidermidis were found in a relatively high proportion in almost all fresh meat samples but were less common in stored meat. In this context, they can be considered as “hygiene indicator bacteria” of meat. Based on these findings, the proportion of the “hygiene indicator bacteria” in relation to the “spoilage indicator bacteria” was calculated to determine a “hygiene index” of meat. This index has a moderate to strong correlation to bacterial loads obtained from culture (p < 0.05), specifically to Pseudomonas spp., LAB and total viable counts (TVCs). Knowledge of the proportions of hygiene and spoilage indicator bacteria obtained by NGS could help to determine the hygiene status even of (heat-) processed composite meat products for the first time, thus enhancing food quality assurance and consumer protection.

Cadaverine as a Potential Spoilage Indicator in Skin-Packed Beef and Modified-Atmosphere-Packed Beef.

This study investigated cadaverine as a spoilage indicator in commercial beef products stored under conditions favourable for the growth of lactic acid bacteria. Samples included vacuum-skin-packed entrecotes (EB) aged up to 42 days and modified-atmosphere-packed (70% O2 + 30% CO2) minced beef (MB) stored at 5 °C. Two MB product lines were analysed: one stored aerobically two days post-slaughter before mincing and another stored for 14 days in vacuum packaging prior to mincing. Sensory assessment/evaluation and microbial analysis were performed throughout the shelf life of the products and compared to cadaverine levels measured using LC-MS/MS. Cadaverine concentrations in EB reached approximately 40,000 µg/kg on the "best before" date, while remaining below 50 µg/kg in both MB products on the corresponding date. While cadaverine concentrations in EB displayed a consistent increase, suggesting its potential as a spoilage indicator post-ageing, the low concentrations in MB, did not correlate with sensory assessments, revealing its limitations as a universal spoilage marker. In conclusion, it is necessary to conduct product-specific studies to evaluate the applicability of cadaverine as a spoilage indicator for beef products.

Impact of frozen storage on quality and cold storage stability of smoked deep-skinned fillets from well-fed Atlantic mackerel

To ensure year-round availability and stability of Atlantic mackerel caught in Icelandic waters during summer after intensive feeding, freezing is essential. Due to the high lipid content and sensitive lipid composition of the fish caught at this time, the fish industry requires detailed research to understand the mechanisms underlying the degradation processes occurring during storage and processing, in order to develop high-value hot-smoked products. Therefore, the impact of frozen storage at − 25 ± 1.8 °C (for 6, 9, and 20 months) prior to hot-smoking, was investigated on the physicochemical, microbial, and sensory quality of deep-skinned, smoked fillets from well-fed Atlantic mackerel caught in late August. The stability of hot-smoked fillets stored at 1 ± 0.6 °C was then monitored for 28 days. Total aerobic viable counts (TVC) remained below acceptable thresholds due to the combined effects of brining, freezing, and hot-smoking, while Listeria monocytogenes was not detected in the hot-smoked products. Slow formation of oxidation products was observed during the chilled storage, especially in the fish frozen for 9 months. Minor lipid deterioration was also detected during sensory analysis, but all spoilage indices remained within acceptable thresholds for shelf-life. Frozen storage for up to 20 months thus effectively maintained the sensory acceptability and suitability of deep-skinned mackerel fillets, making them an excellent choice for the fish-smoking industry.

Exploring the Antimicrobial Potential and Stability of Black Soldier Fly (Hermentia illucens) Larvae Fat for Enhanced Food Shelf-Life.

The larvae of the Black Soldier Fly (BSF, Hermetia illucens) have been introduced as one of the tools to create a circular economy model, which will be used in areas such as waste management and the treatment of industrial by-products to produce high-added-value food grade ingredients. The main aim of this research was to investigate the fat composition and antimicrobial activity against food pathogens and spoilers of Black Soldier Fly larvae. The research revealed that the Black Soldier Fly larvae fats are predominantly lauric fatty (40.93%), which are followed by palmitic, oleic, myristic, linolenic and palmitoleic fatty acids, accounting for 19.11, 17.34, 6.49, 8.79 and 3.89% of the fatty acid content, respectively. The investigation of the fats showed stability through a one-year monitoring period with no indication of chemical or microbiological spoilage. Different fat fractions were tested for antimicrobial activity, which showed efficiency against Candida albicans (the inhibition zone varied from 10.5 to 12.5 mm), Bacillus subtilis (from 12.5 to 16.5 mm), Staphylococcus aureus (12.5 mm) and Escherichia coli (10.0 mm). The inhibitory effect on Candida albicans was confirmed by shelf-life studies using larvae fat-based oleogel in a model food matrix. GraphPad Prism (ver. 8.0.1) was used for the statistical data processing. This research revealed the potential of Black Soldier Fly larvae fat as a very stable ingredient with promising antibacterial properties that can extend the product shelf-life in food matrixes even when used in relatively small amounts.

Influence of polyaniline and cellulose nanocrystals on starch biopolymer film for intelligent food packaging

The development of bioplastics is important to reduce the environmental impact of petroleum-based plastic, while intelligent food packaging is essential in reducing food wastage through the accurate indication of food spoilage. In this research, a biopolymer film that is able to detect food spoilage has been fabricated. Starch is the main matrix of the polymer film, while polyaniline (PANI) acts as the sensor component. The biopolymer film is reinforced with cellulose nanocrystal (CNC) extracted from oil palm empty fruit bunches (OPEFB) to enhance the sensor performance. CNC was successfully extracted from OPEFB with a yield and crystallinity index as high as 41% and 83%, respectively. Various characterization methods were employed to characterize the samples, including FT-IR and UV–vis, while TEM was used to scrutinize the morphology of the CNC. The thermal stability of the bio-nanocomposite films was studied through TGA and DSC. The XRD analysis indicates that CNC improves the crystallinity of the film from 18% to 41%. The performance of the bio-nanocomposite films as an ammonia sensor was studied through an ammonia sensitivity test, where the optimum starch/PANI/CNC 6% film has a limit of detection (LOD) and limit of quantification (LOQ) of 52 ppm and 156 ppm, respectively (R2 = 0.9909, RSD = 3.98%). Also, it shows selectivity to ammonia gas only. Therefore, the starch/PANI/CNC biopolymer film has great potential for its application as intelligent food packaging.

Identification of natural dyes with halochromic properties and their potential use as food spoilage indicators

Purpose The purpose of this research is to identify and investigate some natural dyes with halochromic properties for potential use as food spoilage indicators to reduce waste and curve the negative effects of food borne diseases. Design/methodology/approach Exactly 10 potential dye-yielding plants were selected based on their colour (mostly purple, red, maroon and pink). Solvent extraction was used to extract the dyes and pH differential method was used to determine the concentrations of anthocyanin in the extracted dyes. Different concentrations of hydrochloric acid and sodium hydroxide (0.1 M, 1 M and 2 M) in drops and in excess as acidic and basic solution, respectively, were used to test the halochromicity of the extracted dyes. Methyl red (a synthetic dye) was used as a reference standard/control. The pH of the dyes was recorded before and after addition of both NaOH and HCl solutions. Findings Five out of the 10 dyes extracted (labelled as dye A–E for Ti plant (green Cordyline fruticosa), coleus (Coleus blumei), paper flower (Bougainvillea glabra), painted nettle (Palisandra coleus) and purple heart (Setcresea purpurea), respectively, were found to be halochromic (even at low doses) by changing its colour when exposed to both acidic and basic solutions. While other dyes labelled F–J for red acalypha (Acalypha wilkesiana), golden shower (Cassia fistula), golden dew drop (Duranta repens), wild sage (Lantana camara var Aculeata) and pink oleander (Apocynaceae Nerium oleander), respectively, were either completely insensitive to the solutions in drops, slightly sensitive at high doses or the colour change is insignificant. Although some dyes were found to be more sensitive than others but in most cases, the colour changes in halochromic dyes were more stable in acidic conditions than in basic making it more sensitive to the basic than the acidic solution with the exception of dye A and E (to some extent) which was sensitive to both acidic and basic solution. The anthocyanin contents of dye A–J were found to be between the range of 2.28–10.35 mg/l with dye E having the lowest and dye J with the highest anthocyanin concentration, respectively. The initial pH of all the dyes falls within the range of 4.8–7.3 with most found within the acidic range. Originality/value Halochromic dye research studies are still at the infancy stage in developing world despite the vast available and abundant potential natural halochromic dye-yielding plants. The study explored this area of research and gives an opportunity for the development of smart packaging for pH-sensitive foods using natural dyes as an alternative to conventional synthetic dyes to reduce cost and also curve the negative effect of synthetic dyes as well as food borne diseases.

Обоснование рациональных режимов термического выделения липидов из жиросодержащих рыбных отходов

Many fish waste remaining during the cutting of fish (heads, entrails, bones) contain an increased amount of fat, which has a high biological value. Obtaining edible fat from them is not always possible due to safety requirements, and the production of feed fishmeal with standard quality indicators is difficult. The increased fat content of raw materials and the technology parameters contribute to the rapid rancidity of fat in flour and the formation of toxic substances. This raw material can be used to obtain fish oil with subsequent recommendations for use, taking into account the indicators of oxidative and hydrolytic spoilage and in accordance with the requirements of the standards. When the content of undesirable products is exceeded, it can be used for technical purposes or in industrial biotechnology, as a substrate for microbial synthesis of biodegradable biopolymers such as polyhydroxyalkanoates. In this paper, a thermal method for separating fat from the heads of mackerel and hot-smoked sprats, as waste products from fish canning enterprises in the Kaliningrad region, was studied. A high fat content in raw materials (respectively 24.9 and 20.3%) and its characteristics were established. The rational parameters of the hydromodulus (1:0.5 and 1:1.0) were determined during thermolysis of crushed sprat and mackerel raw materials, respectively, at a stirrer rotation speed in the thermoreactor of 15 rpm. Rational ranges of temperature and duration of thermal release of fat were determined in experiments using mathematical planning. The optimization parameters were the yield of fat, its acid and peroxide numbers. The maximum yield of fat from fish heads is achieved at a temperature of 73-94°C for 2 hours 15 minutes - 2 hours 45 minutes. However, at the same time, fat has increased values of acid and peroxide numbers. Obtaining high-quality fat with food indicators is recommended at a temperature of 68 - 83 ° C for 43 min. – 1 h 22 minutes.

Evaluation of total volatile bases and trimethylamine in hake (Merluccius capensis) fish preserved at low temperature in Vanderbijlpark, South Africa

Fish is one of the most highly perishable food product and its quality aspects are of significance to retailers and consumers. The purpose of this study was to investigate the change in quality of hake (Merluccius capensis) fish preserved at -14°C over a period of seven weeks in other to evaluate fish spoilage indicators. The fish quality parameters assessed were pH, trimethylamine nitrogen (TMA-N) and total volatile bases nitrogen (TVB-N). The data revealed that there was an increase in pH from 7.4 to 7.7 during the storage period. The concentration of TVB-N in the hake samples increased from 7.21 to 23.35 (± 0.036) mg-N/100g while that of TMA-N increased from (range: mean ± std) 3.18 - 3.34: 3.25 ± 0.068 to 13.90 – 15.01: 14.29± 0.493 mg-N/100 g within the seven weeks of preservation, with percent increase of 69.13% (TVB-N) and 77.26% (TMA-N) of the initial amount. The overall data exhibited a steady and consistent increase in the amount of TVB-N, TMA-N and pH in the flesh of hake fish preserved at the temperature and duration of the study. This steady increase in these chemical parameters is a significant potent warning to consumers to resist lengthy storage of fresh fish and its products before consumption. One-way analysis of variance was adopted to assess the validity of the parallel increase of TVB-N, TMA-N, pH with storage duration at low temperature and the analysis revealed no significant differences between increase in the three chemical parameters and storage time. In other words increase in TVB-N, TMA-N, pH content is directly proportional to the increase in storage time. This study have provided useful data to benefit South African retailers on storage and maintenance of TVB-N and TMA-N limits of acceptance in the consumption quality of hake to be sold to consumers and also for consumers on storage duration of hake in their refrigerators before consumption.

Antibacterial efficacy of phenyllactic acid against Pseudomonas lundensis and Brochothrix thermosphacta and its synergistic application on modified atmosphere/air-packaged fresh pork loins

Microbial contamination is a crucial problem that is difficult to solve for the meat industry. Therefore, this study explored the antibacterial efficacy of phenyllactic acid (PLA) against Pseudomonas lundensis (PL) and Brochothrix thermosphacta (BT) solely and in combination (PL + BT). It also provided insights into its synergistic preservation effect during inoculation in chilled (4 °C) fresh pork loins under air (AP) and modified atmosphere packaging (MAP). The minimum inhibitory concentration (MIC) of PLA was 10 mg/mL. Growth kinetics, scanning electron microscopy (SEM), zeta potential, and cell viability investigations showed that PLA treatment exhibited reduced bacterial growth, aided morphological alterations, and leakage in cell membrane integrity in vitro. Nonetheless, PLA and MAP (70 %N2/30 %CO2) showed an excellent synergistic antibacterial ability against spoilage indicators(total glucose, pH, TVB-N, and TBARS), bacterial counts than AP, without impairing organoleptic acceptability. These results demonstrate the broad antibacterial efficacy of PLA as a biopreservative for the meat industry.

Spread of multidrug-resistant Pseudomonas aeruginosa in animal-derived foods in Beijing, China

Pseudomonas aeruginosa is the most common bacterium occurred in nosocomial infections and is also an important indicator of food spoilage. The worldwide spread of multidrug resistant (MDR) P. aeruginosa is threatening public health. However, the prevalence and spread of MDR P. aeruginosa through the food chain is little referred under the One Health perspective. Here, we collected a total of 259 animal-derived foods (168 chicken and 91 pork) from 16 supermarkets and farmer's markets in six regions of Beijing, China. The prevalence of P. aeruginosa in chicken and pork was 42.1 %. The phenotypic antimicrobial susceptibility testing showed that 69.7 % of isolates were MDR, and isolates from Chaoyang district exhibited a higher resistance rate compared to that from Xicheng district (p < 0.05). P. aeruginosa isolates exhibited high levels of resistance against β-lactams (91.7 %), cephalosporins (29.4 %), and carbapenems (22.9 %). Interestingly, none of strains showed resistance to amikacin. Whole-genome sequencing showed that all isolates carried various kinds of antimicrobial resistance genes (ARGs) and virulence genes (VGs), especially for blaOXA genes and phz genes. Multilocus sequence typing (MLST) analysis indicated that ST111 (12.8 %) was the most predominant ST. Notably, the emergence of ST697 clones in food-borne P. aeruginosa was firstly reported. In addition, the toxin pyocyanin was detected in 79.8 % of P. aeruginosa strains. These findings help to decipher the prevalence and the strong toxigenic ability of MDR P. aeruginosa from animal-derived foods and highlight the effective supervision of animal-derived food hygiene should be strengthened to prevent the spread of ARGs in a One Health strategy.

Justifi cation of the choice of raw materials for confectionery safety management

It is shown that a certain set of indicators of oxidative spoilage corresponds to a certain shelf life of confectionery products. The ratio of the induction time, peroxide value, and other indicators allows predicting the safety of confectionery. Diff erent fats have diff erent eff ects on the preservation of vitamins. It has been found that the loss of vitamin B1 in cookies made using sunfl ower oil was 34%. However, in cookies made with palm oil, the loss was only 13%. The infl uence of the quality of peanuts and cashews on the preservation of candy shells has been studied. After storage at a temperature of 18°C, the highest values of the peroxide value were found for the fat fraction of sweets made using peanuts. After 2 months, the induction time of the fat fraction of candy shells decreased by 1.7 times. With an increase in the storage temperature of sweets by 10ºС, the rate of oxidative processes increased by 2 times. This approach can be used to predict the shelf life using the accelerated aging method.