The use of rosemary extract in combination with nisin to extend the shelf life of pompano (Trachinotus ovatus) fillet during chilled storage

The effects of rosemary extract (RE) combined with nisin (N) on the quality of pompano (Trachinotus ovatus) were assessed throughout 15 days of storage at 4 ± 1 °C. Physicochemical (peroxide value, thiobarbituric acid, total volatile basic nitrogen, trimethylamine, pH, K value, texture, and color), sensory, and bacteriological characteristics of fish fillet were all periodically analyzed. RE + N treatment effectively improved physicochemical quality parameters and the sensory, and reduced microbial growth as compared with either treatment of RE or N alone or the control, which resulted in a significant extension in the shelf life of pompano fillet. Therefore, rosemary extract combined with nisin treatment may be a promising method of maintaining the storage quality and extending shelf life of pompano fillet during chilled storage.     

A simple method to evaluate the shelf life of refrigerated rabbit meat

The shelf life of rabbit meat during refrigerated storage was investigated under industrial conditions. Rabbit carcasses were bulk packed (BP), packed under air (PUA) and under modified atmosphere (MAP) (30% O₂:40% CO₂:30% N₂). The main groups studied were mesophilic aerobes, psychrotrophic aerobes, Pseudomonas spp., lactic acid bacteria, yeast and moulds and Enterobacteriaceae. The microorganisms that showed faster growth were psychrotrophic aerobes (growth rate of 0.36 ± 0.09 day⁻¹) for BP, Pseudomonas (0.26 ± 0.03 day⁻¹) for PUA, and lactic acid bacteria (0.22 ± 0.01 day⁻¹) for MAP, and the lag phases were 4, 4 and 8 days, respectively. The main effect of MAP was the increase in lag phase from 4 to 8 days, for lactic acid bacteria, psychrotrophic and mesophilic aerobes. The respective growth rates were similar to those observed with PUA. In addition, MAP inhibited Pseudomonas growth during 18 days. Considering 6 log CFU g⁻¹ as maximum tolerable microbial load, the calculated values of shelf life in BP, PUA and MAP were 6, 7 and 12 days, respectively, when considering the fastest growing microorganisms.     

Combined effects of slightly acidic electrolyzed water and fumaric acid on the reduction of foodborne pathogens and shelf life extension of fresh pork

This study evaluated the efficacy of the individual treatments (slightly acidic electrolyzed water [SAcEW] or fumaric acid [FA]) and their combination to reduce Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium in fresh pork as well as to study the shelf life and sensory quality (color, odor, and texture) of pork during storage at 4 and 10 °C. The inoculated pork samples (10 g) were dipped for 3 min in each treatment (tap water [TW], SAcEW, strong acidic electrolyzed water [StAEW], 0.5% FA, or SAcEW + 0.5% FA) with or without mild heat (40 °C). Decontamination of fresh pork with SAcEW +0.5% FA at 40 °C for 3 min showed greater bactericidal effect compared to other treatments, which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, S. aureus, and S. Typhimurium by 2.59, 2.69, 2.38, and 2.99 log CFU/g, respectively. This combined treatment significantly (P < 0.05) yielded in a longer lag time of naturally occurring bacteria (TBC) on pork stored at 4 °C. This combined treatment also prolonged the shelf life of pork up to 6 days and 4–5 days when stored at 4 °C and 10 °C, respectively, compared to those of the untreated pork. The results suggest that the combined treatment of SAcEW + 0.5% FA has potential as a novel method to enhance the microbial safety and quality of fresh pork.     

The presence,genetic diversity and behaviour of Listeria monocytogenes in blue-veined cheese rinds during the shelf life

Blue-veined cheeses may allow Listeria monocytogenes survival and multiplication due to the biochemical characteristics of the cheese and the growth characteristics of the pathogen. Because of the availability of a considerable number of samples, we wanted this study to take a large view of the microbiota and of the incidence and genetic diversity of L. monocytogenes in blue-veined cheese rinds. Moreover, we wanted to determine if the pathogen present on the rinds at the end of ripening represented a risk to the consumer if the cheese should exceed the domestic storage limit imposed by Commission Regulation (EC) No 2073/2005 for food safety criteria.The rind microflora showed a high level of heterogeneity, and the incidence of L. monocytogenes (never found in the paste samples) was 55%, with an increased presence and concentration associated with a longer ripening time. Amplified Fragment Length Polymorphism (AFLP) was used to characterise L. monocytogenes isolated from blue-veined cheese rinds and highlighted the heterogeneity among the strains, demonstrating its suitability for studying the biodiversity of the pathogen in this environment. L. monocytogenes was able to grow during the shelf life of the cheese and was influenced by the refrigeration temperatures and the physicochemical characteristics of the cheese.     

Understanding and attitude regarding the shelf life labels and dates on pre-packed food products by Belgian consumers

Based on an on-line survey using questionnaires, information on Belgian consumers (n = 907) regarding their understanding and attitude towards shelf life labels and dates was collected. 80.1% of the respondents were familiar with the terminology of the label use by and best before while 69.6% indicated to know the difference between the meaning of the two labels. Judging edibility of food products at home occurs mainly by a combination of checking visually and smelling (82.5%), followed by looking at the shelf life date (67.5%) or tasting (50.4%). About half of the consumers is aware of and appreciates the difference between the two labels during this judgment. Most of the consumers interpret shelf life labels and dates with some flexibility, with variation depending upon the type of food product under consideration. Overall, the share of consumers willing to eat expired refrigerated products was lower than for expired products stored at ambient temperature: 19.1% for refrigerated raw products (e.g. meat and fish); 34.7% for refrigerated ready-to-eat products (e.g. deli-meat, cheese products, smoked fish); 61.0% for canned products (e.g. conserves) and drinks (e.g. beer) and lastly 69.3% for other products generally stored at ambient temperature (e.g. bread, unopened UHT milk, chocolate, cereals). Differences linked to age and gender are discussed. The suboptimal understanding and application of the EU date label framework by consumers may lead on the one hand to increased food disease burden by consuming certain expired use by products allowing growth of pathogens. On the other hand discarding food at the shelf life data in case of a best before date contributes to food waste by consumers. A better understanding of the shelf life labels use by (referring to food safety) and best before dates (referring to food quality) by consumers should be promoted.     

Determination of the shelf life of cluster of the red king crab (Paralithodes camtschaticus) during chilled storage

Red king crab (Paralithodes camtschaticus) presents a commercial and economical important species that is mainly consumed in high-end markets in Japan and USA. The product is either sold live, cooked and refrigerated or frozen. The meat in the legs and in the shoulder is utilized. In this study, shelf life of cooked king crab clusters (shoulder plus three legs) during chilled storage was studied. We utilized sensory, chemical and microbiological methods to describe spoilage during storage of the clusters, and to estimate its shelf life. The results revealed that a cluster is a heterogeneous product, where the shelf life of the leg and shoulder meat is 8 and 5 days, respectively, during chilled storage. As it is impractical to operate with two different shelf lives for the same product, the overall recommended shelf life is 5 days for cooked and chilled clusters. Corresponding maximum level of TVC and Pseudomonas spp. in leg meat stored for 5 days was log 4.6 and 3.7 CFU/g, respectively. A correlation between odour of the shoulder joint and flavour of the leg meat was revealed. By using, exponential regression, the flavour of the leg meat could be predicted based on the odour of the shoulder joint.     

Continuous quality and shelf life monitoring of retail-packed fresh cod loins in comparison with conventional methods

This study investigated the applicability of a new photochromic time-temperature indicator (TTI) to monitor the quality and shelf life of fresh cod loins in retail packs at different storage conditions; also compared this automatic monitoring method with other methods of quality control, such as sensory, chemical and microbiological analyses; and with a shelf life prediction model. TTI placed on the bottom of the packs effectively reflected the temperature condition of the product. TTI with the initial square value of 61 was suitable for continuous monitoring of the quality and shelf life of the product repacked on day 6 after processing. The estimated product shelf lives based on TTI and on the square-root model for relative rate of spoilage of fresh seafood were well correlated.     

Influence of sunflower oil based nanoemulsion (AUSN-4) on the shelf life and quality of Indo-Pacific king mackerel (Scomberomorus guttatus) steaks stored at 20 °C

The influence of nanoemulsion (AUSN-4) on the microbiological, proximal, chemical, and sensory qualities of Indo-Pacific king mackerel (Scomberomorus guttatus) steaks stored at 20 °C was studied for a time period of 72 h. AUSN-4 treatment showed initial reduction (P > 0.05) in the heterotrophic, H₂S and lactic acid bacterial populations in 12 h, followed by a gradual increase in their respective populations. Irrespective of treatments, reduction in total carbohydrate, protein, and fat contents were observed in all samples with an increase in storage time (h), with AUSN-4 treated steaks having the lowest reduction. AUSN-4 treatment significantly (P < 0.05) decreased the values of chemical indicators of spoilage throughout the storage period. Organoleptic evaluation revealed that AUSN-4 treated steaks showed an extension of shelf life of 48 h, when compared with control and antibiotic treated samples, respectively. Based on the results obtained in our present study we conclude that sunflower oil based nanoemulsion preservative technique is able to extend the shelf life and maintain the quality of S. guttatus steaks during storage.     

Shelf life of packaged loins of dried salt-cured cod (Gadus morhua L.) stored at elevated temperatures

Dried salt-cured cod is a commercially important product that is mainly exported to markets in Latin America and Southern Europe. The product is usually split, and cut and packaged once it reaches the market. However, many markets do not have adequate refrigeration facilities. When stored at elevated temperatures, a red or pink discolouration can develop due to the growth of extreme halophiles, at which point the product is considered defective and cannot be sold. We have investigated the shelf life of packaged loins of dried salt-cured cod stored at 25, 30, and 35 °C and at 60 and 80% relative humidity (RH). Shelf life varied by temperature, RH, water content, and level of extreme halophiles. Product stored at 60% RH had a longer shelf life than product stored at 80% RH, and storage at 25 °C revealed a longer shelf life than storage at 30 or 35 °C. At both 60 and 80% RH, drying beyond 48% had a limited shelf life effect. As dried salt-cured fish is largely sold and consumed seasonally, its shelf life has more implications during the low season, as prolonged non-refrigerated storage may cause more product to become defective.     

Extension of the shelf life of chilled hake (Merluccius merluccius) by a novel icing medium containing natural organic acids

Three combinations of two natural organic acids, citric acid (CA) and lactic acid (LA), in the form of novel flake icing systems were evaluated for the preservation of European hake (Merluccius merluccius), one of the most commercialised gadoid fish species in Europe. The flake icing systems were prepared with fresh water and 0.075%/0.050% (C-75 batch), 0.125%/0.050% (C-125 batch) and 0.175%/0.050% (C-175 batch) CA/LA, respectively. Aerobic mesophiles, psychrotrophs, proteolytic bacteria, anaerobes, Enterobacteriaceae, trimethylamine, lipid hydrolysis, primary, secondary and tertiary lipid oxidation events, and pH levels were evaluated in hake muscle in all batches during 13 d of chilled storage and the results were compared with sensory analyses. Significantly (p < 0.05) lower microbial counts were found in the C-175 batch for all five microbial groups investigated when compared with the control batch, with differences between batches of greater than 2 log CFU/g in the case of aerobes and anaerobes. The presence of organic acids in the icing systems also inhibited (p < 0.05) the increase in trimethylamine-nitrogen (TMA-N) content, with greater inhibition as the CA concentration in the ice increased. An inhibitory effect (p < 0.05) on fluorescent compound formation due to the presence of organic acids in the icing systems, which is indicative of tertiary lipid oxidation, was also observed at advanced storage times. These results correlated well with sensory analysis, which revealed that the shelf lives of the C-125 and C-175 batches were extended. The melting of the ice crystals containing the natural organic acid solutions, especially in the C-175 batch, exerted an antimicrobial washing effect that may explain the better protection of hake quality when stored in the proposed flake icing system.     

Screening of antifungal potentials of Lactobacillus helveticus KLDS 1.8701 against spoilage microorganism and their effects on physicochemical properties and shelf life of fermented soybean milk during preservation

This study investigated the screening of antifungal potential of Lactobacillus helveticus. L. helveticus KLDS 1.8701 showed strongest antifungal activity against Penicillium sp. of all provided strains, and antifungal activity was from organic acids and KLDS 1.8701 itself. Results of the impact of KLDS1.8701 on spoilage microorganisms in fermented soybean milk during the preservation period showed that it could inhibit Penicillium sp. and other spoilage microorganisms from the environment and the shelf-life of products were extended. The addition of KLDS 1.8701 has no significant effect on biochemical, rheological and sensory properties of fermented soybean milk. It also enhances total viable counts of Lactobacillus stains (L. helveticus + Lactobacillus bulgaricus)and didn't affect Streptococcus thermophiles. Thus, the use of L. helveticus KLDS 1.8701 as a bio-protective culture in other fermented products was suggested.     

Effects of green tea extract on reducing Vibrio parahaemolyticus and increasing shelf life of oyster meats

This study investigated effects of tea extract on growth of pathogenic Vibrio parahaemolyticus and potential utilization in post-harvest treatment to extend shelf life of Pacific oysters (Crassostrea gigas). Longjing Tea, which exhibited strong bactericidal activity against V. parahaemolyticus, was selected to use in this study. Tea extract containing equal or higher than 4.6 g/l total phenolic contents (TPC) as gallic acid equivalents (GAE) determined by Folin-Ciocalteau method could reduce a mixture of five clinical V. parahaemolyticus strains in tryptic soy broth plus 1.5% NaCl from 4.5 log CFU/ml to non-detectable level (<1 log CFU/ml) within 8 h. A treatment of shucked oysters with tea extract containing 9.1 g/l TPC as GAE for 2 h at 23 ± 1 °C with oyster/tea extract ratio of approximate 0.9 g/ml resulted in greater (p < 0.05) V. parahaemolyticus reductions (0.8 log MPN/g) compared to controls (0.2 log MPN/g). The following shelf life study indicated that green tea treatment at oyster/tea extract ratio of approximate 0.7 g/ml could enhance reducing V. parahaemolyticus while retarding the growth of total bacteria in oysters during 5 ± 1 °C storage. Therefore, green tea might be utilized as a natural antimicrobial agent to inactivate V. parahaemolyticus in oysters and extend the shelf life during refrigeration storage.     

影响氟蛋白泡沫灭火剂储存寿命的因素及延缓变质的措施

从氟蛋白泡沫液组成出发,讨论了影响其储存寿命的因素和延长储存寿命应采取的措施,加入高效防腐剂和缓蚀剂是较为有效的方法。     

Effects of Salmonella bacteriophage,nisin and potassium sorbate and their combination on safety and shelf life of fresh chilled pork

Salmonella is an important foodborne pathogen and a serious threat to human health worldwide. This study was to reduce Salmonella and the spoilage bacteria on fresh chilled pork using bacteriophage, nisin, and potassium sorbate (PS) along with their combinations. Microbial, chemical, and sensory qualities of the fresh chilled pork (artificially contaminated with Salmonella 3 log CFU/g) treated with bacteriophage (9 log PFU/g), nisin (5000 IU/g), PS (2 mg/g) and their combinations were evaluated. The result showed that all the samples treated with phage could significantly (P < 0.05) reduce Salmonella population on fresh chilled pork. The combination treatment of nisin, PS and phage (N-PS-P) could significantly lower total viable counts (TVC), TVB-N and TBARS of the chilled pork during the storage period. The TVC of sample treated by N-PS-P was reduced by 2.3 log CFU/g at 7th day. It was also found through the electronic nose detection that the N-PS-P treatment was able to significantly reduce odour and maintain good sensory of the chilled pork. Hence, the N-PS-P treatment extended the shelf life of fresh chilled pork up to 14 days. No adverse effect of the phage on the chilled pork was observed. In conclusion, this study suggests that the phage and its combination with nisin and PS have great potential to be used as a good preservative for fresh chilled pork.     

Exploring high hydrostatic pressure for enhancing the preservation of white and dark muscle fish fillets stored at different packaging systems under refrigeration

High hydrostatic pressure (HHP) is an old preservation method. However, there is still a gap in the literature about their promising conditions for improving the shelf life and quality of different fish groups (dark and white muscle) at different packaging systems (air and vacuum) stored under refrigeration. Since it is crucial to boost optimization research and enable HHP industrial commercialization, this study aimed to identify promising high hydrostatic pressure (HHP) conditions to extend the maximum fresh fish quality of dark and white muscle fillets stored under air-packing and vacuum-packing (DM-AP, DM-VP, WM-AP, and WM-VP, respectively), considering the bacteriological (total viable aerobic count), physicochemical (lipid oxidation, lightness, redness, yellowness, total color changes, and hardness or firmness), and sensory (appearance, color, odor, texture, and acceptability) characteristics during refrigerated storage. The systematic literature search was carried out in four databases (PubMed, Science Direct, Scopus, and Web of Science) to retrieve articles from 2001 to 2023 published in English. A total of 3,922 articles were retrieved, of which 49 were eligible for systematic review and 47 for meta-analysis. Overall, the best HHP conditions for DM-AP (400 MPa/5 min/5 °C) and DM-VP (400 MPa/5 min/20 °C) extended the microbial and sensory shelf life from about 6 to ≥ 9 days with a positive effect on color (ΔE ≤ 4). Concerning WM-AP, HHP at 220 MPa/10 min/25 °C and 250 MPa/5 min/3 °C did not affect lipid oxidation and extended the sensory acceptability by 2–4 days but negatively influenced hardness and color (ΔE > 5). For WM-VP, HHP at 300 MPa/3 or 10 min/10–20 °C could prolong the microbial and sensory shelf life by 7 days without affecting hardness, decreased lipid oxidation, and color changes (ΔE < 4). Therefore, HHP may enable the shelf life extension of dark and white muscle fish fillets stored under refrigeration in aerobiosis and vacuum while retaining their quality.     

Comparing the effectiveness of chitosan and nanochitosan coatings on the quality of refrigerated silver carp fillets

The coating effects of chitosan and chitosan nanoparticles on the quality of silver carp (Hypophthalmicthys molitrix) fillets during refrigerated storage at 4 °C were compared. Solutions of Chitosan (2%, w/v) and nanochitosan (2%, w/v) were used for the coating. The control and the coated fish samples were analyzed periodically for microbiological (total mesophilic and psychrotrophic count), physicochemical (pH, TVB-N, TBARS), and sensory attributes. The results indicated that both chitosan and nanochitosan coating were effective for the preservation of silver carp fillets during refrigerated storage. However, nanochitosan exhibited higher antimicrobial activity than chitosan during the storage period. Furthermore, nanochitosan showed a stronger ability to inhibit the TVB-N content than chitosan. Therefore, to extend the shelf life and delay the deterioration of fresh silver carp fillets during refrigerated storage, nanochitosan coating is more effective.     

Effects of oregano extract on oxidative,microbiological and sensory stability of sheep burgers packed in modified atmosphere

The aim of this study was to evaluate the effects of oregano natural extract added to sheep burgers packaged in a modified atmosphere for 20 days at 2 ± 1 °C, seeking antioxidant properties and healthiness appeal. Antioxidant capacity of the oregano extract was determined by Folin-Ciocalteau, DPPH and FRAP methods. Three treatments of burgers were prepared: without antioxidant (control, CO), with 50 ppm BHT and with 1000 ppm oregano extract (ORE). The proximate composition (moisture, fat, protein and ash) of the meat product was determined and its stability was assessed through physicochemical (pH value, colour, lipid and protein oxidation, free fatty acids and volatile compounds profile), microbiological [total viable counts (TVC), Pseudomonas spp., Enterobacteriaceae, lactic acid bacteria (LAB)] and sensory analysis (5-point rating scale). ORE treatment presented similar counts of TVC and LAB and, also, an equivalent capacity to slow lipid and protein oxidation after 20 days, in comparison to BHT. The total amount of volatile compounds increased during storage (P < 0.01) and all treatments showed a decrease (P < 0.001) on a* value. However, ΔE_0–20 was higher (P < 0.05) for CO treatment, indicating visual colour changes perceived by consumers. The presence of natural extract prevented the loss of sensory qualities in sheep burgers up to 15 days of storage, being that changes in off-odour were consistent with the microbial results that indicate burgers spoilage. In conclusion, oregano extract presented antioxidant effects quite similar to BHT and thus, can be considered a viable solution for the production of sheep burgers with a healthier appeal.     

钢制压力容器与管道腐蚀剩余寿命可靠性预测

在已有研究成果的基础上,借助数理统计方法,分析认为介质及环境对钢制压力容器 与压力管道的最大腐蚀深度符合Ⅰ型极大值分布,耐腐蚀寿命属于Ⅰ型极小值分布。初步建立了 腐蚀剩余寿命与腐蚀速率及变异系数、腐蚀裕量、可靠度之间的定量关系,得到了确定腐蚀剩余 寿命的计算公式。实例计算表明,该方法比现有腐蚀剩余寿命计算方法更科学、更合理。最后指 出最大腐蚀深度和腐蚀速率等参数的变异系数往往大于0.2,因此不宜用正态分布模型进行压力 容器与管道耐腐蚀剩余寿命的计算与分析。     

High pressure processing pretreatment enhanced the thermosonication inactivation of Alicyclobacillus acidoterrestris spores in orange juice

The spoilage of high acid fruit juices and nectars by Alicyclobacillus acidoterrestris is a major concern to juice manufacturers around the world since it is difficult to detect. In this study, thermosonication (ultrasound and heat, TS) and thermal inactivation of A. acidoterrestris spores in pretreated orange juice were carried out and resistance parameters were estimated. First, the effect of TS acoustic energy density (AED, 0.3–20.2 W/mL) on the inactivation at 75 °C was investigated. Then, the influence of TS temperature (70–78 °C) on the spore inactivation (AED = 20.2 W/mL) was studied. Next, we explored the effect of high pressure processing (HPP) pretreatment of juice on the 20.2 W/mL TS inactivation at the best temperature (78 °C). Lastly, the thermal inactivation of spores in juice heat shocked + 1 min sonicated vs. untreated juice was also investigated.Results of TS showed higher spore inactivation for higher AED (D_75°C-value of 49 min for 20.2 W/mL vs. 217 min for 0.33 W/mL). Lower D-values were obtained at higher temperatures (D_78°C-value of 28 min vs. D_70°C-value of 139 min at 20.2 W/mL). The TS D_78°C-value (at 20.2 W/mL) decreased further from 28 min to 14 min when the orange juice was previously submitted to 600 MPa for 15 min. Thermal treatment alone at 78 °C resulted in almost no spore inactivation, whereas the heat shock + ultrasound pretreatment of juice enhanced the thermal inactivation of spores (D_85°C-value decreased from 69 to 29 min). To conclude, HPP-assisted TS provided the best method for spore inactivation, indicating the benefit of high pressure and power ultrasound technology in addition to heat. TS required at least 8 °C lower temperatures than thermal treatments to achieve the same spore inactivation, which could enhance juice quality and energy savings.