Effect of tea polyphenols on microbiological and biochemical quality of Collichthys fish ball

BACKGROUND: Tea polyphenols (TP), as the most active constituents of tea, are considered natural food additives. This study examined the preservative properties of TP for Collichthys fish ball in well storage. Vacuum‐packed Collichthys fish balls were treated with 0, 0.1, 0.15, 0.20, 0.25, and 0.30 g kg^?1 TP and stored at 0 °C for 17 days. RESULTS: Microbiological results were obtained using a biochemical test, API system kit, and 16S rDNA sequence analysis. Results confirmed that the dominant bacteria in Collichthys fish balls are the genera Serratia and Pseudomonas. Total viable counts dropped two orders of magnitude in Collichthys fish balls with 0.25 g kg^?1 TP compared with the control. The advantages of total volatile basic nitrogen value, 2‐thiobarbituric acid value and texture value were clearly observed, whereas pH and whiteness value exhibited no significant decrease for the group treated with 0.25 g kg^?1 TP. More than 0.25 g kg^?1 TP added could retain excellent fish ball characteristics in terms of sensory assessment after 17 days. CONCLUSION: The shelf life of Collichthys fish balls supplemented with tea polyphenols can be prolonged for an additional 6 days in good condition at 0 °C storage. Copyright © 2011 Society of Chemical Industry     

Effect of silver carp (Hypophthalmichthys molitrix) muscle hydrolysates and fish skin hydrolysates on the quality of common carp (Cyprinus carpio) during 4 °C storage

Silver carp (Hypophthalmichthys molitrix) skin and muscle were hydrolysed, respectively, and then used as part of an edible coating to preserve fish. The effects of muscle and skin hydrolysates as edible coatings for shelf life extension of common carp (Cyprinus carpio) were evaluated over 18 days at 4 °C, by comparing these two treatments, a chitosan coating with muscle hydrolysate, chitosan alone, and an untreated control. All coatings were made up with 5% glycerol. The quality of the carp was assessed by using total volatile basic nitrogen (TVB‐N), total viable counts (TVC), thiobarbituric acid (TBA) and K value. Compared with the control group, the rate of increase in TVB‐N, TVC, TBA and K value of carp coated with fish skin hydrolysates, fish muscle hydrolysates and chitosan added to fish muscle hydrolysates were lower. According to the total viable counts, the storage life of fish with fish skin hydrolysates coatings and chitosan added fish muscle hydrolysates coatings were 16 days, 2 days longer than those with the chitosan coatings and twice as long as the control group.     

Retail Shelf-Life of Pork Dipped in Organic Acid before Modified Atmosphere or Vacuum Packaging

Modified atmosphere packaging (MAP) is increasingly popular for meat, but raw, chilled pork in vacuum or anoxic environments has a purple color. The retail shelf‐life of pork chops dipped in 500 ppm ascorbic acid, 250 ppm citric acid, or no acid dip and stored at 1 °C before simulated retail display in MAP with gas exchange or air‐permeable packaging after vacuum pouch storage was determined. The 80% N₂:20% CO₂ in MAP was exchanged with 80% O₂:20% CO₂, and chops were removed from vacuum packages and overwrapped with permeable film (VP‐PVC) on the 7th day before simulated retail display at 4 °C. Shelf‐life traits were determined at 1, 7, 8, 10, 12, and 14 d postpackaging. The pH values changed with time, but returned to post‐dipped, prepackaged levels at the end of simulated retail storage. Weight loss of chops increased (P < 0.05) in VP‐PVC compared with MAP. The a* values increased (P < 0.05) and L* and b* values decreased during simulated retail display, with higher L*, a*, and b* color values for chops in MAP than VP‐PVC. Log numbers of psychrotrophic microorganisms were higher (P < 0.05) on VP‐PVC samples than for chops in MAP on days 12 and 14. Psychrotrophic counts on ascorbic acid‐treated samples were decreased compared with citric acid or no dipping on pork during simulated retail display. Pork chops in MAP with gas exchange had lighter and redder color, increased weight retention, decreased psychrotrophic counts, and increased lipid oxidation compared with conventional vacuum and overwrap packaging systems.     

Compositional Analyses and Shelf‐Life Modeling of Njangsa (Ricinodendron heudelotii) Seed Oil Using the Weibull Hazard Analysis

This study investigated the compositional characteristics and shelf‐life of Njangsa seed oil (NSO). Oil from Njangsa had a high polyunsaturated fatty acid (PUFA) content of which alpha eleostearic acid (α‐ESA), an unusual conjugated linoleic acid was the most prevalent (about 52%). Linoleic acid was also present in appreciable amounts (approximately 34%). Our investigations also indicated that the acid‐catalyzed transesterification of NSO resulted in lower yields of α‐ESA methyl esters, due to isomerization, a phenomenon which was not observed under basic conditions. The triacylglycerol (TAG) profile analysis showed the presence of at least 1 α‐ESA fatty acid chain in more than 95% of the oil's TAGs. Shelf‐life was determined by the Weibull Hazard Sensory Method, where the end of shelf‐life was defined as the time at which 50% of panelists found the flavor of NSO to be unacceptable. This was determined as 21 wk. Our findings therefore support the potential commercial viability of NSO as an important source of physiologically beneficial PUFAs.     

Sodium Lactate Affects Shelf Life And Consumer Acceptance Of Fresh Catfish (Icfalurus nebulosus, marmoratus) Fillets Under Simulated Retail Conditions

Fresh Ictulurus nebulosus, marmoratus (Speckled Bullhead catfish) fillets were tumbled under vacuum (172.32 kPa for 15 min) with either 0.1, or 2% sodium lactate solutions %(w/w) adjusted to pH 5.50, and stored at 1.11 1°C for 8 days. Shelf life of fillets treated with 2% sodium lactate was extended from 4 to 7 days. Aerobic plate counts and TBA values were lower (P < 0.05) for fillets treated with 2% sodium lactate, compared to controls. Total and fecal coliforms, psychrotrophs, pH, water activity, proximate composition and fatty acid profiles were not affected by sodium lactate. Cooking yields and sodium content were higher for fillets treated with sodium lactate compared to controls.     

Comparison of Shelf Life and Quality of Mullet Stored at Zero and Subzero Temperature

The shelf life and quality of mullet (Mugil spp.) caught off the Southeast Atlantic coast were evaluated during storage at subzero temperature (-2°C) either unpackaged or vacuum packed in iolon film. Subzero temperature was maintained by storing fish in either 2% NaCl- or 7% propylene glycol-ice. Shelf life of fish stored in -2°C ice was 10 days, compared to 7 days for the fish stored in 0°C ice. Extension of shelf life was attributed to delayed microbial growth and slow biochemical changes. Structural changes due to ice crystals at subzero temperature storage appeared to be minor compared to those which occurred during freezing at -20°C as revealed by microscopic examination. The minor structural changes along with insignificant biochemical changes resulted in products having acceptable eating quality for 10 days.     

Inhibition of microbiological activity during sole (Solea solea L.) chilled storage by applying ellagic and ascorbic acids

Fresh fish products are commonly sold at storage temperature. However, many undesirable changes can occur in the products during storage, due to microbial growth and fish spoilage, affording evident economic loss. The effects of ellagic acid (EA) and l-ascorbic acid (l-AA)/sodium ascorbate (SA), either alone or in combination, on the microbiological quality of fresh finfish Solea solea during storage at 0 °C, were investigated.The results showed that addition of EA (0.03%) alone or in combination with l-AA (1.71%)/SA (1.98%) significantly delayed the proliferation of aerobic plate counts, psychrotrophic counts and Pseudomonas bacteria extending the product shelf life up to 10 days, versus 8 days for control. During the storage, the pH increase is slowed down when the fish samples are subjected to the treatment with preservative agents. The effect of lowering the pH increase is particularly pronounced when a combination of EA and l-AA/SA is used. Therefore, EA alone or in combination with l-AA and SA can be successfully utilized to reduce the microbial growth, extending the shelf life of fish during storage at 0 °C.     

Shelf‐life extension of vacuum‐packaged sea bream (Sparus aurata) fillets by combined γ‐irradiation and refrigeration: microbiological,chemical and sensory changes

The combined effect of γ‐irradiation and refrigeration on the shelf‐life of vacuum‐packaged sea bream (Sparus aurata) fillets was studied by monitoring the microbiological, chemical and sensory changes of non‐irradiated and irradiated fish samples using low‐dose irradiation doses of 1 and 3 kGy. Fish species such as sea bream and sea bass are very popular in the Mediterranean countries due to their high quality characteristics, and their preservation is a constant challenge given their extreme perishability. Irradiation (3 kGy) dramatically reduced populations of bacteria, namely, total viable counts (3 vs 7 log cfu g^?1) for the non‐irradiated samples, Pseudomonas spp (<2 vs 7.6 log cfu g^?1), H₂S‐producing bacteria typical of Shewanella putrefaciens (<2 vs 5.9 log cfu g^?1), Enterobacteriaceae (<2 vs 6.0 log cfu g^?1) and lactic acid bacteria (<2 vs 3.5 log cfu g^?1) after 10 days of storage. The effect was more pronounced at the higher dose (3 kGy). Lactic acid bacteria, Enterobacteriaceae and H₂S‐producing bacteria typical of Shewanella putrefaciens showed higher sensitivity to γ‐radiation than did the rest of the microbial species. Of the chemical indicators of spoilage, Trimethylamine (TMA) values of non‐irradiated sea bream increased very slowly, whereas for irradiated samples significantly lower values were obtained reaching a final value of 7.9 and 6.3 mg N per 100 g muscle at 1 and 3 kGy respectively (day 42). Total volatile basic nitrogen (TVB‐N) values increased slowly attaining a value of 67.3 mg N per 100 g for non‐irradiated sea bream during refrigerated storage, whereas for irradiated fish, lower values of 52.8 and 43.1 mg N per 100 g muscle were recorded (day 42). Thiobarbituric acid (TBA) values for irradiated sea bream samples were higher than respective non‐irradiated fish and increased slowly until day 21 of storage, reaching final values of 1.1 (non‐irradiated), 2.0 (1 kGy) and 2.2 mg malonaldehyde kg^?1 muscle (3 kGy), respectively (day 42). Sensory evaluation showed a good correlation with bacterial populations. On the basis of overall acceptability scores (sensory evaluation) a shelf‐life of 28 days (3 kGy) was obtained for vacuum‐packaged sea bream, compared with a shelf‐life of 9–10 days for the non‐irradiated sample. Copyright © 2004 Society of Chemical Industry     

Inhibition of quality loss in chilled megrim (Lepidorhombus whiffiagonis) by employing citric and lactic acid icing

This study focuses on the quality retention of megrim (Lepidorhombus whiffiagonis) during chilled storage. Aqueous solutions of two different concentrations of citric (CA) and lactic (LA) acids were employed as icing media (0.125% CA–0.050% LA and 0.175% CA–0.050% LA, respectively; w/v). The effects of each solution on microbial activity, lipid damage and sensory acceptance were monitored for up to 13 days of storage. Lower (P < 0.05) bacterial growth was detected according to microbiological (aerobe and psychrotroph counts) and chemical (trimethylamine‐N and pH) assessments, which led to an enhancement of sensory appreciation. Whereas control fish were determined as unacceptable at day 13, the acid‐iced fish were still acceptable at that time. Concerning lipid damage, an inhibitory effect (P < 0.05) on fluorescent compound formation was observed in the acid‐iced fish. Present results allow to conclude that the use of a CA–LA icing system can provide a profitable strategy to obtain higher quality chilled fish.     

Microbiological aspects and shelf life of processed seafood products

BACKGROUND: Fresh fish and seafoods are very perishable products mainly owing to microbial activity of specific spoilage micro‐organisms. Application of hurdle technology leads to a variety of processed products with extended shelf life. In this study, sensory evaluation and microbiological analysis were carried out on 17 processed seafood products stored at 4 °C to determine their shelf life and the predominant spoilage micro‐organisms. RESULTS: Shelf life determined by sensory analysis varied from 66 to 180 days depending on the product. The cause of spoilage for most of the products was the development of off‐flavours/off‐odours, while two products were rejected owing to oil discolouration. Pseudomonads were in most cases below detection limit. H₂S‐producing bacteria, Brochothrix thermosphacta and Enterobacteriaceae were below detection limit throughout the experiment. The predominant spoilage micro‐organisms were lactic acid bacteria and yeasts. Hygiene indicators such as Staphylococcus spp. and total coliforms were also below detection limit in all samples. CONCLUSION: Primarily the initial pH and secondarily the NaCl content determined shelf life duration. Under the applied conditions, lactic acid bacteria and yeasts predominated. The contribution of chemical oxidation and/or autolysis to spoilage and shelf life might be important for most of the products. © 2012 Society of Chemical Industry     

In vitro antioxidant activity of papain‐treated grass carp (Ctenopharyngodon idellus) protein hydrolysate and the preventive effect on fish mince system

Antioxidant activities of papain‐treated grass carp protein hydrolysate (HP) were investigated using in vitro methods and in grass carp mince system. Lipid oxidation, colour changes and cooking loss in grass carp mince added with 0% (control), 0.5%, 1.0%, 2.0% and 4.0% HP during refrigerated storage (4 °C) for 8 days was studied. HP could chelate 50% of Fe²⁺ and scavenge 50% of hydroxyl radicals at the concentration of 0.81 and 8.12 mg mL^?1, respectively. And HP could effectively decrease peroxide values and inhibit the formation of thiobarbituric acid reactive substances in fish mince throughout storage (P < 0.05), at the application level range from 0.5% to 4.0%. In HP‐treated samples the formation of conjugate dienes (CDs) was retarded 5–30% at day 6 of storage compared to control. In addition, HP could significantly decrease cooking loss of fish mince samples, at the application level range from 1.0% to 4.0%.     

Stability of docosahexaenoic acid and eicosapentaenoic acid in breads after baking and upon storage

Wholemeal bread and white bread were prepared by substituting shortening with refined menhaden fish oil (0.5%, 1.0% and 1.5% w/w). The stability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were evaluated over 5 days of storage through gas chromatography (GC) analysis along with peroxide and anisidine value determinations. Sensory analysis was also performed by evaluating the fishy flavour, palatability and palatability differences compared to the control bread upon storage. The recoveries of EPA and DHA in breads after baking were 68.7%–72.8% with no further significant changes (P < 0.05) upon storage for both types of breads. Results from GC analyses correlated well with peroxide and anisidine value analyses, which showed relatively low values throughout the storage time. Omega‐3‐fatty acids from Menhaden fish oil can be incorporated into breads by substituting the shortening at a fish oil level of 0.5% (w/w) with acceptable palatability even after a 3‐day storage period.     

Microbiological,chemical and sensory changes of whole and filleted Mediterranean aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of filleting on the microbiological, chemical and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads, H₂S‐producing bacteria (including Shewanella putrefaciens) and Brochothrix thermosphacta were the dominant bacteria at the end of the 16 day storage period in ice for both whole ungutted and filleted sea bass. Enterobacteriaceae were also found in the spoilage microflora of whole ungutted and filleted sea bass, but their counts were always lower than those of pseudomonads, H₂S‐producing bacteria (including S putrefaciens) and B thermosphacta. Total viable counts for whole ungutted sea bass were always lower than those for filleted sea bass samples. Of the chemical indicators of spoilage, TMA (trimethylamine) values of whole ungutted sea bass increased very slowly, whereas significantly higher values were obtained for filleted samples, with respective values of 0.253 and 1.515 mg N per 100 g muscle being reached at the end of their shelf‐life (days 13 and 9 respectively). TVB‐N (total volatile basic nitrogen) values showed a slight increase for whole ungutted sea bass during storage, reaching a value of 26.77 mg N per 100 g muscle (day 13), whereas for filleted fish a corresponding value of 26.88 mg N per 100 g muscle was recorded (day 9). TBA (thiobarbituric acid) values increased slowly for whole ungutted and filleted sea bass samples throughout the entire storage period, reaching final values of 4.48 (day 13) and 13.84 (day 9) mg malonaldehyde kg^?1 respectively. Sensory assessment of raw fish using the EC freshness scale gave a grade E for up to 5 days for whole ungutted sea bass, a grade A for a further 4 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Overall acceptability scores for odour, taste and texture of cooked whole ungutted and filleted sea bass decreased with increasing time of storage. The results of this study indicate that the shelf‐life of sea bass stored in ice, as determined by overall acceptability sensory scores and microbiological data, is 8–9 days for filleted and 12–13 days for whole ungutted fish. Copyright © 2003 Society of Chemical Industry     

Application of Lactobacillus plantarum in Functional Products Based on Fermented Buckwheat

In this work, 12 plant‐based potential probiotic mashes were produced by fermenting buckwheat with lactic acid cocci of the Fresco DVS 1010 culture and the human‐derived isolate Lactobacillus plantarum HM1. The effect of single and coculture fermentation was studied at 30 and 37 ± 0.5 °C for 8 hr (5% CO₂), followed by a storage period of 21 days (6 ± 0.5 °C). Although milk is the typical growth medium for lactic acid bacteria (LAB), presumably viable counts of Fresco reached levels of 10⁸ to 10⁹ CFU/mL (specific growth rates ranging from 1.07 to 1.40 hr^?1) with higher counts in coculture fermentation (13%) that differed statistically significantly (P < 0.05). After storage, 194 to 4700 mg/kg lactic acid was found in the mashes, with significantly higher contents after cocultivation (11% to 96%). Based on the overall acceptance of the designed products, milk‐based mashes right after the fermentation were evaluated as the most satisfactory (3.3 to 3.6). Those after the storage period (21 days) exhibited an attractive sensory acceptability (2.2 to 3.2).     

Development of a process for manufacture of long‐life dairy dessert kheer and its physicochemical properties

Kheer, a traditional milk product of South‐east Asia, containing cooked rice grains in a creamy sweetened concentrated milk, has no large‐scale production owing to its poor shelf‐life. Shelf‐life was improved by developing a process based on in‐pouch thermal processing employing a rotary retort. Product development included optimisation of rice/milk solids ratio (0.18–0.52) and total milk solids levels (16–26%) to simulate the conventional product in taste, appearance and textural attributes. Various process lethality values (F_o = 12.4–14.8) were examined with regard to product quality. While the thiobarbituric acid value tended to increase (0.073–0.081), the reflectance value (35.3–43.4) declined with increasing F_o. The pH of the product (6.04–6.10) showed a slight tendency to increase with F_o. Sensorily, the product was found to be acceptable for a period of 150 days at 37°C.     

Zataria multiflora Boiss essential oil and sodium acetate: how they affect shelf life of vacuum‐packaged trout burgers

The preservative effects of Zataria multiflora Boiss essential oil (ZEO) at 0.025%, 0.05% and 0.1%, sodium acetate (SA) at 2% and their combination on the quality changes of vacuum‐packaged trout burgers during 21‐day refrigerated storage (4 ± 1°C) were investigated. Results showed that control and ZEO‐treated samples reached undesirable levels of rancidity (P < 0.05) at 15th day, whereas samples with the combined effect of SA and ZEOs, especially at higher concentrations, proved to be more stable in sensory, biochemical (PV, TBA, FFA and pH) and microbiological analyses (P < 0.05). Therefore, ZEO+SA‐treated samples showed good overall acceptability even until 21st day. Regarding the results obtained from ZEO‐treated samples, it becomes apparent that combined application of SA and ZEO extended the shelf life of fish burgers during cold storage to 21 days, 1.4‐fold longer than other treatments, which indicates the potential application of synergistic activity of these agents in vacuum‐packaged fishburgers.     

Physiological and biochemical changes of different fresh-cut mango cultivars stored at 5 °C

Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh‐cut produce were investigated. Combinations of calcium chloride (CaCl₂), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh‐cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl₂ + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh‐cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.     

Effects of Soaking with Natural Additives in Combinations with Vacuum or Modified Atmosphere Packaging on Microbial Populations and Shelf Life of Fresh Truffles (Chinese Tuber Indicum)

The objective of this study was to evaluate the relative effects and interactions of combined soaking treatment using citric acid (CTA) and apple polyphenol (APP) at mild heating temperatures for the inactivation of the external and internal microflora (mesophilic aerobic bacteria, mesophilic anaerobic bacteria, and fungi) in Chinese Tuber indicum, as well as to analyze the microbiological and sensory changes under modified atmosphere packaging (MAP)‐ and vacuum atmosphere packaging (VAC)‐packed Chinese T. indicum stored at 4 °C for up to 55 d. Chinese T. indicum was soaked with CTA and APP alone or in combination for 10, 20, and 30 min at 35, 45, and 55 °C. A disinfection method using CTA and APP (3% CTA + 3% APP for 20 min at 45 °C) was obtained. Under this set of combination, the experimental values of microbial counts of mesophilic aerobic bacteria, mesophilic anaerobic bacteria, and fungi were 2.31 ± 0.4 log CFU/g, <1.0 log CFU/g, and <1.0 log CFU/g, respectively. Through the analysis of sensory qualities and microbial populations for MAP‐ or VAC‐packed Chinese T. indicum, the shelf life of soaked truffles was prolonged to 45 or 40 d, respectively. The synergistic effect of CTA and APP may provide valuable insight into the reduction of microorganisms on fresh truffles.     

EFFECT OF HEATING AT DIFFERENT TEMPERATURES TO EXTEND THE SHELF LIFE OF VACUUM-PACKED WHITE CHEESE

The aim of this study was to determine the effects of heating applications on the shelf life of vacuum‐packed white cheese. Shelf life was evaluated for chemical, microbiological and organoleptic properties during the ripening period of 90 days. For this purpose, pickled white cheeses made with commercial starter cultures (Chr. Hansen R707 Lactococcus lactis subsp. lactis, L. lactis subsp. cremoris) were put in polyamide bags for vacuum packaging. During the ripening period, a water bath was used for heating applications at 65, 70 and 72C for 15, 10 and 5 min, respectively. In the ripening period, there were no changes in the values of dry matter in the control group. Dry matter values in control cheese were 40.02–42.09% (average value: 40.87%). Total acidity, protein (%), soluble nitrogen, ripening index (RI), tyrosine content and volatile fatty acid values all showed significant increases between the first and 90th days of the ripening period. However, in the heated cheese groups, dry matter showed no changes, but compared with the control group cheese total acidity, protein (%), soluble nitrogen, RI, tyrosine content and volatile fatty acid values increased but not as much as the control group.     

Using lactic acid bacteria for developing novel fish food products

Lactic acid bacteria‐induced fermentation of fish was tested with the purpose of developing a novel fish food product with desired meat properties. Three selected lactic acid bacteria strains, isolated from lightly preserved fish products, were inoculated into minced frozen fillet of yellowfin tuna, and changes in fish properties were observed during 52 days of storage at 8 °C. Organoleptic, bacteriological and biochemical studies (pH, histamine, TVB‐N, malonaldehyde) and shelf‐life measurements suggest that Leuconostoc mesenteroides could be considered as a possible starter culture for fish fermentation, but additional experiments should be performed. © 2000 Society of Chemical Industry