Volatile components associated with bacterial spoilage of tropical prawns (original) (raw)
Related papers
International Journal of Food Microbiology, 2011
The spoilage potential of six bacterial species isolated from cooked and peeled tropical shrimps (Brochothrix thermosphacta, Serratia liquefaciens-like, Carnobacterium maltaromaticum, Carnobacterium divergens, Carnobacterium alterfunditum-like and Vagococcus penaei sp. nov.) was evaluated. The bacteria were inoculated into shrimps, packaged in a modified atmosphere and stored for 27 days at 8 °C. Twice a week, microbial growth, as well as chemical and sensory changes, were monitored during the storage period. The bacteria mainly involved in shrimp spoilage were B. thermosphacta, S. liquefaciens-like and C. maltaromaticum whose main characteristic odours were cheese-sour, cabbage-amine and cheese-sour-butter, respectively. The volatile fraction of the inoculated shrimp samples was analysed by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC-MS). This method showed that the characteristic odours were most likely induced by the production of volatile compounds such as 3-methyl-1-butanal, 2,3-butanedione, 2-methyl-1-butanal, 2,3-heptanedione and trimethylamine.
Microbial dynamics of prawn.pdf
Food security is a complex issue, where fish and fishery products are generally regarded as high risk commodity in respect of pathogen contents, natural toxins and other possible contaminants and adulterants. They are usually sold as a live product and can be stored for several weeks before consumption. Temperature abuse during prawn postharvesting may allow multiplication of natural spoilage flora as well as pathogens, which imparts a potential threat to consumers and / or compromising product quality. So, Present study focused on the effect of low temperature pasteurization (Roasting, boiling at 60°c for 5 min, 10min, 15min) and storage temperature (25°C,4°C,0°C) on the microbial load of raw prawn. The average count of total bacterial count (TBC), E. coli, Vibrio sp., Salmonella sp., total coliforms, fecal coliforms in raw shell stock prawn were cooperatively higher than raw peeled prawn after 15 min boiling and roasting. It also evident that roasting had a more destructive effect on microbes than boiling when applied on both raw peeled samples and shell stock prawn. The effect of storage temperatures on the microbial status were found significantly higher in shell stock prawn than peeled prawn at all the stored temperature and number of the spoilage bacteria were decreased with storage time and also decreased with lowering the temperature for both shell stock prawn and peeled prawn.
Food security is a complex issue, where fish and fishery products are generally regarded as high risk commodity in respect of pathogen contents, natural toxins and other possible contaminants and adulterants. They are usually sold as a live product and can be stored for several weeks before consumption. Temperature abuse during prawn postharvesting may allow multiplication of natural spoilage flora as well as pathogens, which imparts a potential threat to consumers and / or compromising product quality. So, Present study focused on the effect of low temperature pasteurization (Roasting, boiling at 60°c for 5 min, 10min, 15min) and storage temperature (25°C,4°C,0°C) on the microbial load of raw prawn. The average count of total bacterial count (TBC), E. coli, Vibrio sp., Salmonella sp., total coliforms, fecal coliforms in raw shell stock prawn were cooperatively higher than raw peeled prawn after 15 min boiling and roasting. It also evident that roasting had a more destructive effect on microbes than boiling when applied on both raw peeled samples and shell stock prawn. The effect of storage temperatures on the microbial status were found significantly higher in shell stock prawn than peeled prawn at all the stored temperature and number of the spoilage bacteria were decreased with storage time and also decreased with lowering the temperature for both shell stock prawn and peeled prawn.
Food Science and Technology International, 2010
An inventory of the most part of sulfur-containing volatile compounds (SCVCs) present in seafood was carried out. These molecules constitute key compounds to understand and improve seafood quality. According to their nature, concentration and environmental parameters (temperature), they can move the overall seafood odor from desirable to rotten. Sulfury odors can also indicate problems in sanitary quality. Thus, it is essential to monitor the generation of these compounds to better control the organoleptic and sanitary quality of seafood. SCVC were divided in two categories: aliphatic compounds and cyclic compounds. Among cyclic SCVC, several families of compounds can be distinguished as thiophenes, thiazoles and their respective derivatives. The main pathways of formation of SCVC in seafood are investigated in order to better understand their presence in seafood aroma. Microbial mediated enzymatic reactions are mainly implied in the generation of aliphatic SCVC whereas Maillard reactions are involved in the generation of cyclic SCVC. A small part of SCVC could also derive from the environment by direct bioaccumulation of S-containing molecules or precursors. Then, the occurrence of SCVC in seafood is discussed according to the extraction methods, analysis methods sometimes olfactometric methods and the species the state and the average biochemical composition of the seafood matrix in which they were recovered. Finally, among the identified SCVC, the odorant properties of odor-active volatile compounds were investigated. Aromatic notes and odorant thresholds for odorant SCVC of seafood aroma are listed. Both pathways of formation and lists of SCVC linked to their odorant properties constitute important indicators to optimise seafood quality from an organoleptic and sanitary point of view.
Volatile profile of Atlantic shellfish species by HS-SPME GC/MS
Food Research International, 2012
A procedure based on headspace solid-phase microextraction (HS-SPME) and GC-MS analysis was developed to investigate the volatile organic compounds (VOCs) of Atlantic shellfish species. The experimental conditions (fiber coating, sample volume, time and temperature of incubation) were optimized for the extraction of VOCs from shellfish. The incubation of a Carboxen/Polydimethylsiloxane (CAR-PDMS) fiber with 6 mL of saline aqueous extract heated at 80°C for 30 min gave the most effective and accurate extraction of the analytes. Under these experimental conditions, thermal degradations of volatiles that could be occurred during the extraction process were not observed. The method was validated in terms of linearity, repeatability, inter-day precision, recovery and sensitivity. Then, the optimized method was applied to study the volatile profile of mussels (Mytilus galloprovincialis), pullet carpet shells (Venerupis pullastra), oysters (Ostrea edulis), pod razor shells (Ensis ensis), common cockle (Cerastoderma edule) and goose barnacle (Pollicipes cornucopia). The results showed significant differences in the volatile profile, resulting some of the compound characteristic for the shellfish species. The fatty acid profile has been also investigated and the occurrence of non methylen interrupted fatty acids (NMI) in these species was related with specific volatiles. The present investigation provides the first VOC description of Atlantic E. ensis, V. pullastra, C. edule and P. cornucopia and highlights the important contribution of SPME methodology to identify volatile markers of the natural flavor of seafood, which are useful for the evaluation of origin and represent a starting point to find useful volatiles as freshness markers before commercialization or changes due to processing.
International Journal of Food Science & Technology, 2015
This study evaluated the influence of packaging atmosphere (air versus 50% N 2 /50% CO 2 ) on microbiological (mesophiles, psychrotrophs), physical (gas measurement) and chemical (pH, total volatile basic nitrogen [TVB-N], NH 3 , H 2 S and biogenic amines) parameters in freshwater prawns during storage at 0 AE 1°C for 240 h. To select the most appropriate packaging, 21 batches of each treatment were analysed. Both the packaging permeability and the combination of gases affected the shelf life, but the modified-atmosphere packaging (MAP) was more efficient than air packaging, increasing the shelf life by 40 h. The parameters of pH and TVB-N showed no statistical difference between the two atmosphere conditions all along the storage period. The biogenic amine agmatine showed potential for use as a quality indicator due to the increased concentration during storage. In further studies, this amine can be applied as an indicator for public health issue.
Foods
The present study focused on the determination of color, flavor, taste, and volatile organic compounds (VOCs) changes of shrimp paste fermented for 1, 2, 3, and 8 years by E-nose, E-tongue, and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). During fermentation, the color of shrimp paste turned dark brown with decreases in L*, a*, and b* values. Inorganic sulfide odor was dominant in all fermented samples. The umami, richness, and aftertaste-B reached a maximum in year 3 of fermentation. A total of 182 volatiles, including long-chain alkanes, esters, aldehydes, olefins, ketones, acids, furans, and pyrazines, were detected. Sixteen VOCs including dimethyl disulfide, methional, trimethyl-pyrazine, (E,E)-2,4-heptadienal, benzeneacetaldehyde were selected as flavor markers. Correlation analysis showed that 94 VOCs were related to saltiness while 40, 17, 21, 22, and 24 VOCs contributed to richness, umami, aftertase-B, sourness, and bitterness, ...
2012
Quality changes of aerobically packed cod fillets stored under different temperature conditions were characterized by the growth of specific spoilage organisms (SSO) and the production of microbial metabolites measured by an electronic nose along with traditional sensory and chemical analysis (TVB-N, pH). A new process based on quick contact freezing and cold air blasting was used to achieve superchilling of fillets, prior to chilled (0.5 °C) or superchilled (-1.5 °C) storage. Additionally, the effect of temporarily storing conventionally processed chilled cod at higher temperatures to imitate possible scenarios of abusive conditions during initial handling and transport were studied. Photobacterium phosphoreum dominated under temperature abusive conditions coinciding with high levels of TVB-N and increased electronic nose responses at sensory rejection. CO sensor responses indicated that alcohols and aldehydes contributed to the spoilage odors under all storage conditions. Pseudomo...