Deterioration and shelf-life extension of fish and fishery products by modified atmosphere packaging

Fish and fishery products have been recognized as a nutrition source due to their high protein content. Moreover, theycontain considerable amount of unsaturated fatty acids, especially omega-3 fatty acids, which are regarded as preventivecompounds. However, shelf-life of seafood is limited by biochemical and microbiological changes. Modified atmospherepackaging (MAP) is widely used for minimally processed fishery products including fresh meat for retarding microbial growthand enzymatic spoilage. CO2, O2, and N2 are most often used in MAP. CO2 enriched atmosphere inhibits the autolyticdegradation of fish muscle during storage. However, high levels of CO2 negatively affect product quality, especially by increasingdrip loss and altering texture. Development of satisfactory methods for shelf-life extension that ensure qualitymaintenance of products with minimum loss has drawn the attention of food technologists. The application of MAP andcombination process in seafood is a promising preservation method to extend the shelf-life of fish and fishery products

Sensory and Physical Properties of Pla-duk-ra (Dried Fermented Catfish) at Different Conditions of Drying

In southernmost Thailand, big scale production of catfish demands a development of new lines of catfish-based products to fully utilize the raw material.  Pla-duk-ra (dried fermented catfish) is one such innovation. Traditional method of sunlight drying is commonly used to dry Pla-duk-ra. However, products are highly prone to contamination since they are dried in exposed area. Direct exposure to sunlight could also affect heat labile and light-sensitive nutrients.  In this study, other methods of drying were investigated to dry Pla-duk-ra with improved hygiene practice, physical properties and sensory profile.  Two scenarios were studied in this work. The objective of the first scenario was to determine the best range of temperature to dry a good and acceptable Pla-duk-ra by comparing open sun drying (range 40˚C to 50˚C) and shade drying (under the roof; 30˚C to 40˚C) . The best range of temperature obtained was then used for the second scenario where open sun, infrared and tray drying were further studied. Moisture content, water activity, colour,  texture profile analysis were performed on the Pla-duk-ra samples. Fried Pla-duk-ra was used in sensory evaluation to investigate consumer’s acceptance and preference. Open sun drying was found to be more superior to dry Pla-duk-ra resulting in darker shade of product as compared to shade drying. The moisture content for open sun drying and shade drying of Pla-duk-ra were reported 23.65% and 28.06%, respectively. Infrared heater gave the highest water activity (0.77) with the highest score for redness. Meanwhile, Pla-duk-ra dried under the hot-air tray resulted in the highest score for brightness (L*). Overall acceptance by the consumer showed that the Pla-duk-ra dried under the hot-air tray was the most preferred followed by open sun drying and infrared heater drying. To this end, hot-air tray drying could be applied in drying Pla-duk-ra in large scale production

Induction and inhibition of film yeast from fermented bamboo shoot by seasoning plants

Three samples of fermented bamboo shoot taken from a village in Amphur Kokpho, Pattani Province, were microbiologically examined. Total viable count was between at 104-105 cfu/ml while pH range was between 3.4-4.4. Isolation and identification of film yeast on surface of fermented liquid revealed Saccharomyces cerevisiae J1, Candida krusei J2 and Candida krusei J3. When film yeast was cultivated in liquid culture with different NaCl concentrations (0, 2.5, 5 and 7.5% (w/v)), all species tolerated 2.5% NaCl addition. However, growth decreased depending on NaCl concentration. S. cerevisiae J1 grew faster than C. krusei J2 and C. krusei J3. The cultivation of film yeast in medium with different agar concentrations (0.3, 0.5, 1 and 1.5% (w/v)) within 24 h showed that 0.3% was the optimal agar concentration. Seasoning plants (garlic, ginger, galangal, lemon grass, lesser galangal, clove, kaffir lime, garcinia and shallot) were extracted with water (3% (w/v)) and tested for growth inhibition. Results showed the clove extract inhibited all yeast strains within 12 h and after that the efficiency of inhibition was decreased. At low concentration of 0.75% (w/v) clove extract could inhibit film yeast in fermented bamboo shoot

Biochemical composition and physicochemical properties of two red seaweeds (Gracilaria fisheri and G. tenuistipitata) from the Pattani Bay in Southern Thailand

The proximate composition, dietary fiber, element and amino acid contents, as well as some physicochemical propertiesof the two red seaweeds (Gracilaria fisheri and G. tenuistipitata) collected from the Pattani Bay in Southern Thailand in therainy and summer seasons of 2006 were determined in order to evaluate their potential nutritional value. The protein content ofG. tenuistipitata (21.6% DW) was significantly higher than that of G. fisheri (11.6% DW) (P<0.05). The two seaweed speciescontained lipid (1.7–3.6% DW), ash (7.9–22.9% DW), total dietary fiber (TDF) (57.5–64.0% DW), soluble dietary fiber (SDF)(15.6–18.8%DW) and insoluble dietary fiber (IDF) (38.9–45.2% DW). G. tenuistipitata collected in the rainy season hadhigher level of lipid (P<0.05) whereas the level of ash was higher in the summer. In contrast, G. fisheri had higher levels oflipid, ash and TDF (P<0.05) when collected in rainy season. There was no significant differences in SDF, ISF and TDF betweenthe two seaweeds. The result indicated that the two species contained high levels of K and Cl. The essential amino acidswith the highest content in the two species were arginine, leucine and threonine. The swelling capacity (SWC), water holdingcapacity (WHC) and oil holding capacity (OHC) ranged from 5.2 to 12.5 ml/g DW, 5.5 to 10.1 g/g DW and 1.8 to 2.3 g oil/gDW, respectively, with the SWC, WHC and OHC of G. tenuistipitata being higher than those of G. fisheri. This studysuggested that both Gracilaria species could potentially be used as raw material or ingredients to improve nutritive valueand functional properties in human diet and animal feed

Nutritional composition and physicochemical properties of two green seaweeds (Ulva pertusa and U. intestinalis) from the Pattani Bay in Southern Thailand

The chemical composition, amino acid, and element contents, as well as some physicochemical properties of Ulvapertusa and U. intestinalis, collected from the Pattani Bay in Southern Thailand in the rainy and summer seasons of 2007–2008, were investigated in order to gain more nutritional information. It was found that the two green seaweed speciescontained high level of protein (14.6–19.5% DW), lipid (2.1–8.7% DW), ash (25.9–28.6% DW), soluble fiber (25.3–39.6% DW),insoluble fiber (21.8–33.5% DW) and total dietary fiber (51.3–62.2% DW). Comparing the element contents of the two species,U. pertusa was rich in Mg, K and Ca, while U. intestinalis was rich in Mg, K, Cl, Na, and Ca. The essential amino acids of thetwo species were rich in leucine, valine, and arginine contents. The most limiting essential amino acid of both species waslysine. However, the nutritional composition of the two seaweeds varied depending on seasonal change. As for the physicochemicalproperties of both seaweeds, their swelling capacity (SWC), water holding capacity (WHC), and oil holding capacity(OHC) ranged from 4.0 to 6.4 ml/g DW, 7.8 to 15.0 g/g DW and 1.4 to 4.8 g oil/g DW, respectively. WHC and OHC of U.intestinalis was higher than those of U. pertusa (P<0.05). This study suggested that both species could be potentially usedas raw materials or ingredients to improve the nutritive value and texture of functional food and healthy products for humanbeings

Effect of lactic, acetic and citric acids on quality changes of refrigerated green mussel, Perna viridis (Linnaeus, 1758)

Effect of lactic, acetic and citric acids on the quality changes and shelf-life extension of green mussel stored at 4oC was investigated. The inhibitory effect on bacterial growth was pronounced when the concentration of lactic, acetic and citric acids increased (P<0.05). Green mussel dipped with lactic acid had the lower total volatile base, trimethylamine, ammonia and TCA-soluble peptides contents than those dipped in acetic and citric acids. However, the increases in exudates loss and cooking loss were observed in samples dipped in organic acids, causing the denaturation of muscle protein by acids used. Thiobarbituric acid reactive substances (TBARS) increased as the organic acid concentration increased (P<0.05). Lactic acid dipped samples, particularly with 0.2 M, showed the greater acceptability than did those dipped in other acids throughout the storage of 27 days. The control sample had the acceptability only for 6 days of storage

Extending the shelf-life of refrigerated green mussel (Perna viridis) under modified atmosphere packaging

The effect of modified atmosphere packaging (MAP) on the keeping quality of green mussel stored at 4C was investigated.Inhibition of the bacterial growth increased proportionally to the CO2 concentration in the packaging, and maximuminhibition was achieved with 100% CO2. Mussel stored under CO2-enriched atmosphere had lower total volatile base, trimethylamineand TCA-soluble peptide contents than those stored in air (P<0.05). However, the increase in exudate loss wasobserved for samples packaged in high-CO2 atmosphere, suggesting the denaturation of muscle proteins by carbonic acidformed. The odor and flavor acceptability of CO2-enriched packaged samples, particularly with 80 and 100% CO2, wasaccepted throughout the storage of 12 days, compared with six days for those stored in air. Therefore, MAP with 80% CO2,10% O2 and 10% N2 was chosen as the optimum condition for extending the shelf-life of green mussel. Packaging withinclusion of O2 should be considered to avoid the outbreak of strictly anaerobic toxin producing bacteria

Viability of Lactobacillus plantarum TISTR 2083 in protectant during low-temperature drying and storage

Low-temperature drying was applied as simple and low cost drying technique for the production of dried Lactobacillus plantarum TISTR 2083, which was isolated from traditional starter of Ka-nom Tuay-fu. To improve the survival of L. plantarum TISTR 2083 during drying and storage, five different protectants and two carrier materials were investigated. These include sucrose, trehalose, maltodextrin, skim milk, and L-glutamate sodium salt (L-GSS) as protectant and rice starch and rice flour as carrier material. Whereas, skim milk as protectant with rice starch resulted in higher viable cell (8.71 log CFU/g) after drying by hot air oven at 40 °C. Different concentration 5, 10, and 15% (w/v) skim milk also investigated to check the effect of skim milk concentration on cell viability. L. plantarum TISTR 2083 starter powder was in different storage conditions to check the storage stability. After 90 days of storage, starter powder stored at 4 °C with silica gel and without silica gel had more than 80% survival rate, while there was no viable cell that stored in room temperature with silica gel. The result showed the production and storage conditions of high viability L. plantarum TISTR 2083, which can be used as starter culture for further fermented product development and as probiotic

Sensory and physical properties of Pla-duk-ra (Dried Fermented Catfish) at different conditions of drying

In southernmost Thailand, big scale production of catfish demands a development of new lines of catfish-based products to fully utilize the raw material. Pla-duk-ra (dried fermented catfish) is one such innovation. Traditional method of sunlight drying is commonly used to dry Pla-duk-ra. However, products are highly prone to contamination since they are dried in exposed area. Direct exposure to sunlight could also affect heat labile and light-sensitive nutrients. In this study, other methods of drying were investigated to dry Pla-duk-ra with improved hygiene practice, physical properties and sensory profile. Two scenarios were studied in this work. The objective of the first scenario was to determine the best range of temperature to dry a good and acceptable Pla-duk-ra by comparing open sun drying (range 40˚C to 50˚C) and shade drying (under the roof; 30˚C to 40˚C) . The best range of temperature obtained was then used for the second scenario where open sun, infrared and tray drying were further studied. Moisture content, water activity, colour, texture profile analysis were performed on the Pla-duk-ra samples. Fried Pla-duk-ra was used in sensory evaluation to investigate consumer’s acceptance and preference. Open sun drying was found to be more superior to dry Pla-duk-ra resulting in darker shade of product as compared to shade drying. The moisture content for open sun drying and shade drying of Pladuk-ra were reported 23.65% and 28.06%, respectively. Infrared heater gave the highest water activity (0.77) with the highest score for redness. Meanwhile, Pla-duk-ra dried under the hot-air tray resulted in the highest score for brightness (L*). Overall acceptance by the consumer showed that the Pla-duk-ra dried under the hot-air tray was the most preferred followed by open sun drying and infrared heater drying. To this end, hot-air tray drying could be applied in drying Pla-duk-ra in large scale production