Effect of heating on physical properties and microstructure of black tiger shrimp (Penaeus monodon) and white shrimp (Penaeus vannamei) meats

Effects of heating on cooking loss, texture, colour and microstructure of black tiger shrimp (Penaeus monodon) and white shrimp (Penaeus vannamei) meats from different parts were evaluated. Cooking loss increased sharply when the samples were heated for longer time, particularly more than 1 min (P < 0.05). Among all parts, tail part of both shrimps had the highest cooking loss. The shear force of all samples increased markedly when the samples were heated for longer time, especially more than 0.5 min (P < 0.05). Black tiger shrimp and white shrimp meats had the slight differences in shear force either before or after heating. L*, a* and b*‐values increased when heating time increased up to 1 min (P < 0.05). Similar microstructures between raw meats of black tiger shrimp and white shrimp were found. Cooked meats of both species had more compact fibre arrangement with the shrinkage of sarcomere, compared with raw samples. Generally, tail portion showed the denser structure than other parts.     

Bacteriological quality of individually quick-frozen (IQF) raw and cooked ready-to-eat shrimp produced from farm raised black tiger shrimp (Penaeus monodon)

One thousand, two hundred and sixty four samples of individually quick-frozen (IQF) peeled and deveined raw and 914 samples of cooked ready to eat shrimp samples produced from farm raised black tiger (Penaeus monodon) obtained from a seafood unit working under HACCP concept were analysed for total aerobic plate count (APC), coliform count,Escherichia coli, coagulase positive Staphylococci andSalmonella. The overall bacteriological quality of the product was found to be good. Of the frozen raw shrimp, 96% of samples showed APC below 10⁵while 99% of the frozen cooked ready-to-eat samples showed APC less than 10⁴. The APC ranged from 1.0×10²to 4.2×10⁶cfu/gm in frozen raw shrimp and from 1.0×10²to 6.4×1⁴cfu/gm in the frozen cooked shrimp. Prevalences of coliforms in raw shrimp and cooked shrimp samples were 14.4% and 2.9% respectively. The coliform count in raw products ranged from 1.0×10¹to 2.5×10³cfu/gm and in the cooked products, from 1.0×10¹to 1.8×10²cfu/gm. Although all the cooked shrimp samples were free of coagulase positive staphylococci,E. coliandSalmonella, 1.0, 2.0 and 0.1% of the frozen raw shrimp samples tested positive for coagulase positive Staphylococci,E. coliandSalmonellarespectively. TheSalmonellastrain was identified asSalmonella typhimurium. The results of the present study highlight the importance of implementation of HACCP system in the seafood industry to ensure consistent quality of frozen seafood.     

Enumeration of coliforms and Escherichia coli in frozen black tiger shrimp Penaeus monodon by conventional and rapid methods

Conventional (most probable number, MPN) and rapid methods-including Chromocult coliform agar (CCA), Fluorocult(R) LMX broth (LMX), and Petrifilm Escherichia coli count plates (PEC) for enumeration of coliforms and E. coli in frozen black tiger shrimp from Thailand were compared in order to assess the possibility of using one of the rapid methods for routine analysis. Enumeration of coliforms and E. coli from 18 samples of regular frozen black tiger shrimp and 156 samples of frozen black tiger shrimp experimentally contaminated with coliforms or E. coli at concentrations of approximately 10, approximately 10(2), and approximately 10(3) CFU g(-1) revealed that at the level of approximately 10 CFU g(-1), coliform numbers ranked as LMX>CCA>MPN=PEC and E. coli as MPN=LMX=PEC=CCA. At the level of approximately 10(2) CFU g(-1), coliform numbers ranked as LMX>MPN=PEC=CCA and E. coli as MPN=LMX>PEC=CCA. At the level of 10(3) CFU g(-1), coliforms ranked as LMX>MPN=CCA>PEC and E. coli as MPN>LMX>CCA>PEC. Agreements with the conventional MPN method for coliforms were LMX 108%, PEC 87.2%, and CCA 91.2% and agreements for E. coli were LMX 101%, PEC 95.7%, and CCA 96.3%. Sensitivities (%) ranked LMX>MPN>CCA=PEC for coliforms and E. coli, whereas equal specificities (100%) of all methods for coliforms and E. coli were demonstrated. Rankings for the other parameters compared were: convenience, PEC>CCA=LMX>MPN; time to detection, MPN>LMX=PEC=CCA; expense, MPN=PEC>CCA>LMX; labor, MPN>LMX=CCA>PEC; accuracy for coliforms, PEC>CCA>MPN>LMX; and accuracy for E. coli, PEC=CCA>LMX>MPN.     

Importance of conformation for the IgE reactivity of sarcoplasmic calcium-binding protein from the black tiger shrimp Penaeus monodon

Sarcoplasmic calcium-binding protein (SCP) is an EF-hand Ca²⁺-binding protein recently identified as a new crustacean allergen. Some EF-hand Ca²⁺-binding allergens, such as parvalbumin (fish allergen) and Bet v 4 (birch pollen allergen), have been shown to contain conformational-type IgE epitopes associated with the Ca²⁺-chelating. This study was performed to clarify the relationships between IgE reactivity and structure of the black tiger shrimp SCP. When analyzed by ELISA in the absence and presence of EGTA, the IgE reactivity of the black tiger shrimp SCP was found to be considerably reduced by Ca²⁺-depletion. Furthermore, circular dichroism spectral data showed a conformational difference between Ca²⁺-bound and Ca²⁺-depleted forms of the black tiger shrimp SCP. On the other hand, the synthetic 18 peptides spanning the entire amino acid sequence of the black tiger shrimp SCP were all assessed to have little IgE-binding ability by ELISA. Our results demonstrate that the IgE reactivity of the black tiger shrimp SCP is attributable mostly to conformational-type IgE epitopes, at least part of which is maintained by Ca²⁺-chelating.     

Effect of raspberry pomace extracts isolated by high pressure extraction on the quality and shelf‐life of beef burgers

Raspberry pomace extracts isolated with supercritical carbon dioxide (SCE) and pressurised ethanol/water (ETE) were tested in beef burgers. Only ETE additives effectively inhibited lipid oxidation and the growth of microorganisms, as it was observed by measuring the changes of thiobarbituric acid reactive substances, bacterial counts and the content of O₂ and CO₂ during storage in the modified atmosphere package. ETE additives also demonstrated some meat colour preservation effects, which were assessed by the intensity of hamburger colour and metmyoglobin concentration. However, ETE additives did not alter burger's taste at the applied concentrations (up to 1%). It may be concluded that the most effective extracts possessing strong antioxidant and antimicrobial activity may be isolated from raspberry pomace by the pressurised liquid extraction with a hydroethanolic solvent; such extracts may be considered as promising additives in meat products for improving their stability and enriching with beneficial to health phytochemicals.     

Incidence of vibrios of public health significance in the farming phase of tiger shrimp (Penaeus monodon)

The incidence of some of the human pathogenic vibrios in the cultured tiger shrimp (Penaeus monodon) was evaluated during the farming phase in practice at a commercial semi-intensive shrimp farm off Uttarakannada, Karnataka (India). Possible sources of these human pathogens were also evaluated. Vibrio alginolyticus was found to be the most common Vibrio member (57% incidence). Vibrio cholerae, V parahemolyticus and V vulnificus were the other species encountered. All these occurred in shrimp pond sediment, pond water and the feed used (clam meat and formulated feed). Vibrio mimicus was encountered only in the dam meat used as a shrimp feed. A poor correlation between the faecal coliform level and the occurrence of these pathogenic vibrios was apparent, implying natural occurrence of these vibrios in the brackishwater/shrimp culture environment.     

Effects of initial albumen quality and mineral oil–chitosan emulsion coating on internal quality and shelf‐life of eggs during room temperature storage

Effects of mineral oil (MO) and mineral oil–chitosan emulsion (MO:CH = 25:75) as coatings on internal quality and shelf‐life of eggs were evaluated during 5‐week storage at 25 °C. Eggs with three different initial albumen qualities [Haugh unit (HU): H = 87.8, M = 75.6 and L = 70.9] were evaluated. As storage time increased, HU and yolk index values decreased whereas weight loss increased. Coating with MO and/or 25:75 MO:CH emulsion could preserve the internal quality for at least 4 more weeks for H‐eggs and at least 3 more weeks for M and/or L‐eggs, all with weight losses <0.92%. All coated eggs had >70% positive purchase intent, and their colour differences at week 0 could not be detected by naked human eye (ΔE^* < 3.0, noncoated eggs as reference). Consumers significantly differentiated freshly MO‐coated from noncoated eggs on overall surface appearance. This study demonstrated that MO and 25:75 MO:CH emulsion coatings could preserve internal quality and prolong shelf‐life of eggs.     

Effect of O2 scavenger on the shelf‐life of catfish (Pangasius sutchi) steaks during chilled storage

BACKGROUND: Active packaging for preserving meat products, including seafoods, has been gaining importance in recent times. The present study was undertaken to assess the effectiveness of O₂ scavenger, the most widely used active packaging technology, on the shelf‐life of catfish steaks in chilled storage conditions. RESULTS: O₂ scavenger was effective in reducing the oxygen concentration inside the packaging to as low as 0.42% within 24 h. This reduction in oxygen in O₂ scavenger packages showed positive effects on quality parameters compared to control air packs. Total volatile base nitrogen (TVB‐N), thiobarbituric acid value and peroxide value of catfish steaks packed in O₂ scavenger was significantly different (P < 0.05) compared to air‐packed samples. Based on the sensory, microbiological and TVB‐N values, the control samples were acceptable only up to 10 days, compared to 20 days in O₂ scavenger‐packed samples, extending the shelf‐life by 10 days. CONCLUSION: O₂ scavenger reduced the oxygen concentration inside the package significantly within 24 h compared to control air packs. By using this technique, the use of a vacuum packing machine can be avoided. Further, O₂ scavenger extended the product's shelf‐life up to 20 days, compared to 10 days in control packs. Copyright © 2007 Society of Chemical Industry     

Effect of nano‐TiO2‐LDPE packaging on microbiological and physicochemical quality of Pacific white shrimp during chilled storage

Nano‐TiO₂‐modified low‐density polyethylene (NTLDPE) packaging was prepared by blending LDPE with nano‐TiO₂. The effects of NTLDPE packaging on quality of Pacific white shrimp during storage at 4 °C were investigated. Results showed that NTLDPE lowered the K value by 28.50%, while increased sensory score by 30.77% in comparison with the control. NTLDPE packaging retarded the decrease of whiteness and water holding capacity and the increase of melanosis score based on the signs of freshness and deterioration of shrimp. Furthermore, NTLDPE packaging reduced total viable counts (TVC) by 6.42% and total volatile basic nitrogen (TVB‐N) contents were 14.82% lower than that of control. TVB‐N content and TBARS value, as well as polyphenol oxidase activity and TVC, were maintained and shrimp remained a commercial acceptability for 8 days. The overall results indicated that NTLDPE packaging could preserve the quality and extend the shelf‐life of Pacific white shrimp.     

不同贮藏温度和包装方式对菊花脑品质的影响

研究了不同贮藏温度和包装方式对菊花脑采后贮藏期间生理品质变化的影响,测定了贮藏期间菊花脑的黄化率、失重率和呼吸强度、还原糖、维生素C、叶绿素和纤维素含量,并进行了感官评价。结果表明,低温贮藏可有效抑制菊花脑的呼吸速率,减少营养物质损失,延长菊花脑货架寿命;结果同时表明,10℃和0℃下挽口包装比敞口包装效果好,而在常温下敞口包装效果优于挽口包装。      

不同包装材料对半干青鱼常温贮藏过程中品质的影响

以半干青鱼为研究对象,测定感官评分、水分含量、pH、菌落总数、硫代巴比妥酸(thiobarbituric acid,TBA)值、挥发性盐基氮(total volatile basic nitrogen content,TVB-N)等指标,探究了普通聚乙烯包装和乙烯-乙烯醇共聚物(ethylene-vinyl alcoh...     

Prevalence of bacteria of public health significance in the cultured shrimp (Penaeus monodon)

The prevalence of some human pathogenic bacteria, namelySalmonella, Vibriospp. andListeria monocytogenes, in shrimps under different stages of farming operations was determined by using standard methods.SalmonellaandVibriowere present in all samples analysed.Listeriaspp. was absent from all the samples except clam meat analysed during the farming phase and sediment and shrimps at harvest. A poor correlation was observed between the level of indicator organisms (coliforms) and the incidence of these pathogens, indicating that these pathogens are a part of the natural microfauna of the shrimp culture environment.     

不同生物保鲜剂对冷藏南美白对虾的保鲜效果

为提高冷藏南美白对虾的贮藏品质,分别采用0.05%溶菌酶、0.1%植酸、0.5%柠檬酸、0.15%抗坏血酸、0.5%L-半胱氨酸和1.5%壳聚糖保鲜对虾,通过感官评价、pH、细菌总数、挥发性盐基氮和多酚氧化酶相对酶活力的测定评价保鲜效果。研究结果表明,1.5%壳聚糖能有效减缓新鲜对虾感官品质的下降,并抑制微生物生长,0.5%柠檬酸对挥发性盐基氮抑制效果最好,并有较强的抑制多酚氧化酶作用,0.5%L-半胱氨酸能有效抑制多酚氧化酶和黑变,而0.05%溶菌酶、0.1%植酸和0.15%抗坏血酸对南美白对虾的品质改善不明显。      

Effect of storage temperature and size of stalks on quality of minimally processed leeks

Minimally processed leek stalks were produced by trimming of freshly harvested leeks (Allium porrum L.) to sizes of 0–22, 0–11 and 11–22 cm. Trimmed stalks were then stored at 0, 10 and 20 °C in air for 8 days to determine the effects of temperature and stalk size on quality during storage, including inner leaf growth, fresh weight loss and discoloration. Both inner leaf growth and fresh weight loss were increased linearly with storage duration. Growth of cut leek inner leaves was significantly reduced to 4 mm at the end of 0 °C storage in all three types of cut stalks. Inner leaf growth was maximized during storage at 10 and 20 °C in 0–11 cm stalks, medium in 0–22 cm stalks and minimal in 11–22 cm stalks. Fresh weight loss of 0–11 cm size was significantly higher than that of 0–22 cm size at both 0 and 10 °C, whereas there was no difference between 0–11 and 11–22 cm sizes. At 10 and 20 °C the 0–11 cm size lost more weight than the 11–22 and 0–22 cm ones. Differences in color attributes were observed in most cases between stalk sizes, due to different coloration of intact leeks. Discoloration was observed particularly at the stalk base at 20 °C. Low temperatures effectively control discoloration, and reduce considerably inner leaf growth of minimally processed leeks, but do not control it. Copyright © 2005 Society of Chemical Industry     

Cellulose nanoparticles synthesised from potato peel for the development of active packaging film for enhancement of shelf life of raw prawns (Penaeus monodon) during frozen storage

In this study, the cellulose nanoparticles (CNP) isolated from potato peel were used for reinforcement of polyvinyl alcohol (PVA)-based active packaging film. The above film was used to pack the raw prawns (Penaeus monodon) at −20 °C, and the colour change, protein content, TVB-N, TMA and microbial analysis were done at regular interval for prawns stored in CNP-PVA active packaging film. A significant difference was observed in the quality of prawns stored in potato CNP-PVA film compared with prawns packed and stored in polyethylene film. The newly designed active packaging with CNP and fennel seed oil enhanced the shelf life of prawns up to two months for both HOSO (head on shell on) prawn and PD (peeled and deveined) prawn. Hence, the study recommends the potato peel CNP-PVA film with fennel seed oil as better choice to extend the shelf life of the prawns during storage compared with polyethylene packaging.     

Accelerated storage and isothermal microcalorimetry as methods of predicting carrot juice shelf‐life

The possibility of predicting the shelf‐life of pasteurized carrot juice by isothermal microcalorimetry or change in pH was investigated and compared with traditional plate count results. A small increase in thermal power (2 µW), maximal increase of and acceleration of thermal power all gave rapid, well‐correlated results for the shelf‐life, as did pH, during accelerated storage. The effect of accelerated storage (17 °C) on the microbial flora of pasteurized carrot juice was also compared with the flora from storage at 8 °C, and it was found that accelerated storage is feasible for the rapid evaluation of shelf‐life, but that the microbial flora in the spoilt juice will be different. Copyright © 2004 Society of Chemical Industry