Influence of processing on the extension of shelf-life of Nagli-fish (Sillago sihama) by gamma radiation

Studies were carried out to evaluate the microbiological profile, shelf-life and quality of Nagli fish (Sillago sihama) subjected to gamma irradiation. Non-irradiated samples were unacceptable organoleptically after 7–8 days of storage at 1–2°C while irradiated samples (2 and 3 kGy) were acceptable up to 19 days. Dressing prior to irradiation had no additional advantage to shelf-life over whole fish. Total bacterial count (TBC), total volatile basic nitrogen (TVBN), trimethylamine (TMA) and sensory evaluation data revealed no significant differences between whole and dressed fish. Salmonella sp. were not detected in 3 kGy-irradiated samples whereas 2 kGy destroyed Vibrio parahaemolyticus and Staphylococcus aureus. Listeria monocytogenes and Yersinia enterocolitica were not detected but non-pathogenic species such as L. grayi, L. murrayi, and Y. tuberculosis were present in the fish prior to irradiation. Irradiation doses of 2 and 3 kGy destroyed Yersinia sp. and Listeria sp., respectively. These organisms were not detected during storage of the treated fish.     

Active Packaging of Fresh Chicken Breast,with Allyl Isothiocyanate (AITC) in Combination with Modified Atmosphere Packaging (MAP) to Control the Growth of Pathogens

ABSTRACT: Listeria monocytogenes and Salmonella typhimurium are major bacterial pathogens associated with poultry products. Ally isothiocyanate (AITC), a natural antimicrobial compound, is reportedly effective against these pathogenic organisms. A device was designed for the controlled release of AITC with modified atmosphere packaging (MAP), and then evaluated for its ability to control the growth of L. monocytogenes and S. typhimurium on raw chicken breast during refrigerated storage. In order to obtain controlled release during the test period, a glass vial was filled with AITC and triglyceride. It was then sealed using high-density polyethylene film. The release of AITC was controlled by the concentration (mole fraction) of AITC in the triglyceride and by the AITC vapor permeability through the film. The fresh chicken samples were inoculated with one or the other of the pathogens at 10⁴ CFU/g, and the packages (with and without AITC-controlled release device) were flushed with ambient air or 30% CO₂/70% N₂ before sealing, and then stored at 4 °C for up to 21 d. The maximum reduction in MAP plus AITC (compared to MAP alone) was 0.77 log CFU/g for L. monocytogenes and 1.3 log CFU/g for S. typhimurium. The color of the chicken breast meat was affected by the concentration of AITC. Overall, a release rate of 0.6 μg/h of AITC was found to not affect the color, whereas at 1.2 μg/h of AITC the surface of the chicken was discolored.     

枯草芽孢杆菌素延长香肠货架期的研究

研究了枯草芽孢杆菌B.C119代谢产生的细菌素对香肠中细菌的抑制作用,并与山梨酸钾的抑菌效果进行对照,对香肠进行感官指标、pH、菌落总数的测定.结果表明:枯草芽孢杆菌素能有效的抑制香肠中细菌的繁殖,从而延长香肠的货架期,并且效果要优于山梨酸钾.     

用复合防腐剂延长汀州烧大块货架期的研究

用Nisin、乳酸钠、山梨酸钾、茶多酚构成的复合防腐剂,对汀州烧大块进行处理,真空包装后贮藏于25℃环境中,每隔10d检测菌落总数、pH值和进行感官评定.结果表明:复合防腐剂可有效地延长烧大块的货架期;保鲜效果最佳的配比为 Nisin0.4g/kg、乳酸钠4.5g/kg、山梨酸钾1.0g/kg、茶多酚0.3g/kg.     

Postharvest shelf-life extension of avocados using methyl cellulose-based coating

Edible coatings regulate water vapor, oxygen and carbon dioxide transfer in or out of the produce thereby influencing the ongoing respiratory activity and produce quality. The objective of this study was to evaluate the effect of a methyl cellulose-based coating on the respiration rate, color and texture of avocados stored at room temperature. Avocados were initially surface disinfected, washed and air-dried. They were then immersed in the coating solution for 1 min at 20 °C, air-dried for 10 min and stored at 20 °C in an open box. At 2-day intervals, fruits were removed and evaluated for respiration rate, color and texture. Respiration rate was evaluated by measuring the rate of CO₂ produced from a given quantity of fruits per unit time. Color and texture of avocados were measured using instrumental techniques. Coated avocados demonstrated lower respiration rates, greener color and higher firmness as compared with the uncoated control during the entire storage. The appearance of brown spots and mesocarp discoloration normally associated with fruit ripening were delayed in the coated fruits.     

Use of neutral electrolysed water (EW) for quality maintenance and shelf-life extension of minimally processed lettuce

Experiments were conducted to determine the effectiveness of different treatments based on the use of neutral electrolysed water (EW) on fresh-cut lettuce. EW was diluted to obtain different free chlorine concentrations (120, 60 and 12 ppm) and to compare with standard washing treatment of 120 ppm chlorine solution. Shelf-life quality and safety markers were studied at the beginning and at the end of the 7-day-storage at 4 °C. The use of EW decreased the respiration rate of the samples which might be related with the observed reduction in microbial spoilage. The use of EW also increased the activity of a browning-related enzyme (polyphenoloxydase) although sensory results showed all samples as acceptable at the end of the 7 day-storage. Perhaps longer storage time might increase the risk to browning development in the samples treated with EW. The highest EW concentration (120 ppm free chlorine) was the most effective treatment in reducing sample microbial load; however this treatment also affected the final produce with effects such as loss of turgor, plasmolysis and a reduction in mineral content.Results suggest an intermediate EW concentration with 60 ppm free chlorine could be an alternative to 120 ppm chlorine (from sodium hypochlorite) for sanitizing fresh-cut vegetables, reducing to half the amount of chlorine used and maintaining the antimicrobial effectiveness and without differences affecting the quality. However further studies will be necessary in order to observe the effect of the oxidising capacity of EW on other quality and safety markers as pathogens and nutritional content.Industrial relevanceChlorine solutions have been widely used to sanitise fruit and vegetables in the fresh-cut industry. However, the association of chlorine with the possible formation of carcinogenic chlorinated compounds in water has called into question the use of chlorine in food processing. The efficacy in controlling the microbial load and browning of samples treated with electrolysed water shows it as a promising decontaminant agent for fresh-cut lettuce. Due to the high oxidising potential of the EW quality requirements must be balanced to obtain the optimal treatment conditions keeping satisfying safety levels. The use of EW-60 showed similar safety and quality (browning) results as the use of chlorine or double EW concentration (EW-120). However the treatment EW-120 affected negatively the textural properties. The study suggests the use of EW-60 as an alternative to sodium hypochlorite solution with 120 ppm available chlorine, obtaining similar safety and quality results and reducing the amount of chlorine needed. Further investigations in the effect of EW on lettuce, such as those on pathogens or nutritional markers (e.g. carotenoids and vitamin C) are recommended in order to explore this alternative that might reduce the increasingly concerning use of chlorine to decontaminate this type of product.     

Bacterial microflora of carp (Cyprinus carpio) and its shelf-life extension by essential oil compounds

The microflora of common carp (Cyprinus carpio) skin, gill and intestine were analysed and the antimicrobial activities of garlic oil and nine constituents of essential oils (allyl isothiocyanate, carvacrol, cinnamaldehyde, citral, cuminnaldehyde, eugenol, isoeugenol, linalool and thymol) against the carp isolates were studied to identify compounds that might extend the shelf-life of carp fillet. A total of 90 isolated strains were identified to belong to seven genera: Acinetobacter (6), Alcaligenes (2), Bacillus (2), Flavobacterium (20), Micrococcus (2), Moraxella (6) and Pseudomonas (4), and two families Enterobacteriaceae (14) and Vibrionaceae (34). The dominant micro-organisms of carp were found to be Flavobacterium (37%) and Vibrionaceae (33%) in skin, Flavobacterium (33%) in gill and Vibrionaceae (63%) and Flavobacterium (37%) in intestine. Against these isolates, thymol, carvcarol and cinnamaldehyde had the strongest antimicrobial activities, followed by isoeugenol, eugenol, garlic oil, and then citral. The antimicrobial properties of the other constituents tested (cuminnaldehyde, linalool and allyl isothiocyanate) were low. In tests of mixed compounds, a combination of carvacrol and thymol had the highest antimicrobial activity. Moraxella, Flavobacterium and Vibrionaceae were more sensitive to the compounds, whereas Alcaligenes strains were resistant. Dipping carp fillets in a solution of 0.5% carvacrol and 0.5% thymol before storage at 5°C and 10°C reduced both the total microbial load by about 100-fold and the Volatile Bases Nitrogen (VB-N), as compared with controls. In addition, dipping treatment delayed bacterial growth and extended the shelf-life of the fillets from 4 to 12 days at low temperature (5°C). However, the treated and control fillets showed little difference during storage at 10°C. Data from sensory evaluation showed that dipped fillets in 1% (carvacrol+thymol) extended the shelf-life of carp fillets by 8 and 4 days at 5° and 10°C, respectively. Thus, carvacrol and thymol dipping can improve the microbial stability of fish fillets by removing bacteria and by inhibiting bacterial growth.     

山梨酸和涂膜联合作用延长青虾货架期的效果

将经过山梨酸处理后的青虾浸渍于不同的壳聚糖涂膜溶液后冰藏保鲜,其中壳聚糖复合膜液是将山梨酸加入壳聚糖溶液中制得。在保鲜过程中测定青虾细菌总数、TVB-N值、pH等鲜度指标并进行感官评分,探索采用山梨酸和涂膜联合作用延长青虾货架期的效果。实验结果表明:仅经过山梨酸处理的青虾保鲜效果不佳,而在山梨酸处理后再进行涂膜保鲜可以抑制虾体细菌总数的增长,维持较低的TVB-N值,改善青虾的感官质量,延长青虾货架期约3d。壳聚糖空白膜液处理的青虾感官品质优于经过复合膜液处理的青虾。      

Effect of vacuum packaging on shelf-life extension of cooked and peeled harpiosquillid mantis shrimp (Harpiosquilla raphidea) during refrigerated storage

Effects of vacuum packaging (VP) on quality changes of cooked and peeled harpiosquillid mantis shrimp (HMS) during storage at 4 °C of 15 days were investigated. VP inhibited bacterial growth as ascertained by the lower rate of increases in total viable and psychrotrophic bacteria counts as well as other pathogenic and spoilage bacteria counts. VP samples had lower total volatile base and trimethylamine contents as compared to the sample packed in air (AP). Clostridium perfringens was undetectable in both samples. During storage, VP samples possessed lower pH than AP counterpart. Exudate and TCA-soluble peptide (TSP) contents of sample increased during the storage, regardless of packaging atmospheres. Fatty acid (FA) content, especially PUFA and MUFA, was decreased after 9 and 15 days of storage for AP and VP samples, respectively. The cooked and peeled HMS contained 32 volatile organic compounds, consisting of several aldehydes and alcohols. Carnobacterium and Pseudomonas were mainly involved in spoilage in samples as confirmed by next generation sequencing.     

Preparation and use of freshwater fish,rohu (Labeo rohita) protein dispersion in shelf-life extension of the fish steaks

A process to enhance shelf-life of freshwater fish, rohu, on ice using combination treatment of coating the fish steaks with gel dispersion from the same fish and low-dose gamma irradiation is described. Washed pieces of freshwater fish, rohu were converted into gel by dilute acetic acid treatment. The gel was homogenized in water to a dispersion having 29 g/L protein, apparent viscosity of 1.0 Pa s and pH 3.5. Coating of fresh rohu steaks by dipping in the dispersion for 1 h or gamma irradiation at 1 kGy gave a shelf-life of 32 days in ice, in comparison to 20 days for the untreated steaks. Irradiation at 1 kGy of the dispersion-coated steaks enhanced their shelf-life to 42 days. Bleaching of the pink colour of the steaks by the treatment was prevented when one of either butylated hydroxy anisole or ascorbic acid was incorporated at 5 g/kg (w/v) in the dispersion.     

Influence of salting and gamma irradiation on the shelf-life extension of threadfin bream in ice

Fresh, eviscerated threadfin bream (Nemipterus japonicus) packaged in polyethylene pouches were dipped in 10% (w/w) sodium chloride for 1 h and subjected to gamma irradiation at 0, 1 or 2 kGy at ice temperature. The treated fish were stored under ice. At periodic intervals, quality of the fish was determined by sensory, chemical and microbiological parameters. The unsalted and unirradiated fish was acceptable up to 8 days in comparison to a storage life of 12 and 22 days for the unsalted fish irradiated at 1 and 2 kGy, respectively. Salting prior to irradiation at 0, 1 or 2 kGy gave a shelf life of 9, 14 and 28 days, respectively. Salting gave a firmer texture to the fish and prevented drip formation in the pouches during storage. The results suggested that while irradiation could significantly (P< 0.05) extend the refrigerated shelf life of threadfin bream, salting prior to irradiation could enhance the acceptability of the irradiated fish.     

Effect of oxygen- and carbon dioxide-enriched atmospheres on shelf-life extension of refrigerated ground pork

The oxidation of the lipids and myoglobin of ground pork meat stored in oxygen- and carbon dioxide-enriched atmospheres at 1 °C has been studied. Elevated oxygen levels (80-100%) depressed myoglobin oxidation, increasing the time to 50% metmyoglobin formation from four to about thirteen days. Twenty per cent carbon dioxide greatly reduced the rate of lipid oxidation, extending the time to reach a TBA number of 5 from five to about twelve days. Tocopherol and ascorbic acids were efficient inhibitors of lipid oxidation but citric acid was not.     

Use of nanoliposome loaded with chitosan-epigallocatechin gallate conjugate for shelf-life extension of refrigerated Asian sea bass (Lates calcarifer) slices

Treatments of chitosan-epigallocatechin gallate (CE) conjugate nanoliposome (CELP) and unencapsulated CE conjugate (UNCE) at different concentrations (0.025  and 0.05 g 100 g⁻¹) on quality and shelf-life of Asian sea bass slices (ASB-S) kept at 4 °C were studied. Total viable count of ASB-S treated with 0.05 g 100 g⁻¹ CELP (SB-CELP-0.05) was less than permissible limit (6 log CFUg⁻¹ sample) within 15 days. Moreover, SB-CELP-0.05 sample had the lowest pathogenic and spoilage bacterial count than remaining samples during the storage (P < 0.05). Lower thiobarbituric acid reactive substances and peroxide values were obtained for SB-CELP-0.05 sample than those treated with 0.05 g 100 g⁻¹ UNCE (SB-UNCE-0.05) at the end of storage (P < 0.05). The result was also advocated by higher polyunsaturated fatty acid content of SB-CELP-0.05 than SB-UNCE-0.05 (P < 0.05). Therefore, CELP efficiently extended ASB-S shelf-life with high consumer acceptability at 4 °C for minimum 12 days, whereas control had the shelf-life less than 6 days.     

Allyl isothiocyanate actions on populations of Sitophilus zeamais resistant to phosphine: Toxicity,emergence inhibition and repellency

The risks associated with the use of synthetic insecticides have caused increased interest in the research of essential oils and their main constituents for use in the pest management of stored products. Allyl isothiocyanate (AITC) is the main component of mustard essential oil and has been reported as a potential replacement pesticide for conventional insecticides that control stored product insect pests. Here, we assessed the toxicity (including emergence inhibition) and repellent actions of AITC on Brazilian populations of the maize weevil Sitophilus zeamais (Coleoptera: Curculionidae) resistant to conventional insecticides (e.g., phosphine). We also evaluated physiological (e.g., respiration) and behavioral (e.g., walking and flight) traits of AITC-exposed insects. The AITC showed consistent insecticidal activity against the populations resistant to phosphine and other synthetic insecticides, with LC₅₀ values ranging from 1.5 to 2.9 μL L⁻¹. Significant inhibition of the offspring emergence was achieved after the exposure of parental adults to sublethal levels (i.e., LC₁ and LC₅) of AITC. Reductions in respiration rates were also registered in all the populations sublethally exposed to AITC. In all five populations, a high number of insects avoided AITC-treated (1.5 μL L⁻¹) grain masses, and although individuals of a phosphine-susceptible (i.e., Abre Campo) population increased walking and reduced flight activities, individuals of another phosphine-susceptible (i.e., Tunápolis) population exhibited higher flight activity under AITC exposure. Thus, our findings suggest that AITC is a potential tool that may be integrated into the control strategies of maize weevils where resistance to phosphine and other conventional insecticides is a problem.     

Effects of bactericides and modified atmosphere packaging on shelf-life of Chinese shrimp (Fenneropenaeus chinensis)

Effects of different bactericides and modified atmosphere packaging (MAP) on aerobic plate counts (APCs), total volatile base-nitrogen (TVB-N) and organoleptic evaluation of overall acceptable score (OA score) of Chinese shrimp (Fenneropenaeus chinensis) during cold storage were investigated. Results indicated that APC in MAP(40%CO₂/30%O₂/30%N₂) shrimp treated with compound bactericide reached 10⁷ cfu/g on the 13th day of storage, while that of ozonated water or water control treatments exceed 10⁷ cfu/g on the 9th day. APC in shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide reached close to 10⁷ cfu/g at day 13, while that of air treatment exceed 10⁷ cfu/g. TVB-N value in MAP(40%CO₂/30%O₂/30%N₂) shrimp treated with compound bactericide was slightly higher than the upper threshold of 30 mg/100 g on the 17th day, while that of ozonated water treatment or water control increased to or over the threshold value on the 9th day. TVB-N value in shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide were significantly lower than that of air control on the 17th day (P ≤ 0.01), with a value of 33.6 mg/100 g and 42-47.6 mg/100 g respectively, compared to 78.4-86.8 mg/100 g in air control. The lowest OA score of MAP(40%CO₂/30%O₂/30%N₂) whole and decapitated shrimps treated with compound bactericide appeared on the 17th and 21th day, respectively, compared with the 9th day in whole shrimp and the 13th day in decapitated shrimps treated with ozonated water and water control. The lowest OA score of whole and decapitated shrimps treated with MAP (40%CO₂/30%O₂/30%N₂) or 100%CO₂ after soaking with compound bactericide appeared on the 17th and 21th day, respectively, compared with the 13th and 17th day in air control. In conclusion, when combined the parameters determined together, the shelf-life of Chinese shrimp at 2 ± 1 °C, either whole or decapitated, treated with MAP (40%CO₂/30%O₂/30%N₂) and 100%CO₂ after soaking with compound bactericide were 13 and 17 days, respectively.     

Use of gamma radiation in sheep butter manufacturing process for shelf-life extension

Gamma-irradiated sheep cream (1 kGy) was used to produce butter that was analysed during refrigerated storage up to 90 days in shelf-life extension studies including sensory, microbiological and water content assessments. The water content of the sheep butter made with irradiated fermented cream was 10% higher than that of control butter. A slower increase in bacterial load during storage was detected for the butter manufactured with irradiated fermented sheep cream compared with control butter; however, fungi increased at similar rates in both cream-irradiated and control butters during storage. The sensory evaluation suggested, in general, the acceptance of the irradiated samples by the panellists. The microbiocidal potential of gamma radiation of fermented sheep cream was highlighted, but was not reflected in extension of shelf-life of the butter produced. The traditional manufacturing process itself was found to be a major vehicle for microbial contamination of this dairy product, preventing its shelf-life extension.     

Preservation and shelf-life extension of shrimps and clams by high hydrostatic pressure

Clam ( Venus gallina ) and shrimp ( Parapenaeus longirostris ) samples were high hydrostatic pressure (HHP) treated at 200, 220 and 250 MPa at 25, 30, 40 and 50 °C for 10 and 20 min. Based on the results of microbial reduction, the best combinations of HHP treatments were determined as 250 MPa, 50 °C, 10 min for shrimps and 220 MPa, 50 °C, 10 min for clams. HHP-treated samples stored at 25 °C (room tempertur) and 4 °C (refrigeration temperature) were analysed. According to the results evaluated, shelf-life of shrimps was found to be 12 and 16 days for storage at room and refrigeration temperatures, respectively, as compared with 4 days for non-HHP-treated samples at 4 °C. Similarly shelf-life for the clam samples was found to be 12 days for storage at room temperature and 18 days for storage at refrigeration temperature as compared with 4 days for non-HHP-treated samples at 4 °C.