Microbiological and chemical changes in freshwater prawn (Macrobrachium rosembergii) stored under refrigeration

Abstract

Microbiological and chemical changes were evaluated in freshwater prawn stored under refrigeration at 0°C and 5°C during 10 days, with special emphasis on indole production as a chemical spoilage indicator. The total psychrotrophic and indole positive microflora were mainly mesophilic, with indole positive microorganisms being less than 10% of the total microflora after 10 days storage under refrigeration. Bacteria from Enterobacteriaceae and Vibrionaceae families prevailed among the isolated indole positive strains. The use of the Most Probable Number-MPN method, using tryptone broth as culture medium, was the most reliable approach for the quantitative evaluation of the indole positive microflora. The stored samples showed increases in pH, L-tryptophan and total volatile bases (TVB), which were more intensive at 5°C. The psychrotrophic counts and TVB values of samples stored at 0°C were lower than the recommended limits (10 7 CFU/g and 30 mg N/100g, respectively), even after 10 days storage. However, in samples stored at 5°C, these values were reached after 10 and 5 days, respectively. The presence of indole in levels above the limit recommended by FDA/USA (25 µg/100g) was confirmed in only one sample, suggesting that this substance, alone, wouldn't be a good indicator of freshwater prawn quality stored under refrigeration.

Assessment of caramote prawn(Penaeus kerathurus)proximate value and freshness under ice storage

“…At ice storage, it was determined as 9 days. It was longer than those found in other studies (HANPONGKITTIKUN et al,1995;LEITAO & RIOS, 2000;VARLIK et al, 2000;GÖKOĞLU, 2004;LAGHMARI & EL MARRAKCHI, 2005) and fall within those reported by VARLIK (1993) and LEITAO and RIOS (2000) for several shrimp species.…”

Alterações na qualidade do camarão de água doce Macrobrachium rosenbergii durante estocagem em gelo

“…O baixo crescimento microbiano neste estudo pode ser atribuído à microflora mesófila original do M. rosenbergii que, por ser de águas tropicais, se torna apta a iniciar o crescimento sob temperatura de refrigeração somente após um longo período de adaptação [20]. Os resultados iniciais encontrados estão abaixo dos reportados por ANGEL et al [1], que constataram log 6,1 e 8,3UFC/g em M. rosenbergii recém abatido e após 14 dias de estocagem em gelo, respectivamente.…”

“…Os resultados iniciais encontrados estão abaixo dos reportados por ANGEL et al [1], que constataram log 6,1 e 8,3UFC/g em M. rosenbergii recém abatido e após 14 dias de estocagem em gelo, respectivamente. LEITÃO & RIOS [20] relataram que a contagem de psicrotróficos permaneceu constante em M. rosenbergii, armazenados inteiros e sem contacto com o gelo, como no presente estudo. Entretanto, as médias observadas entre os tratamentos, para os atributos odor e sabor, não foram significativas.…”

Microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) in ice

“…Few studies have been published on the microbiological quality characteristics of farm-reared freshwater prawn stored in ice/stored under refrigeration (Leitào & Rios, 2000;Surendran, Thampuran, & Gopakumar, 1995) in contrast to a wealth of information available on chemical and sensory characteristics (Angel, Bhasker, Kanner, & Juven, 1981;Angel, Weinberg, Juven, & Lindner, 1985;Ninan, Bindu, Asok Kumar, & Joseph, 2003;Rodrigues, Basu, & Hazra, 2000). Little is known about the actual spoilage process and the speciWc spoilage organisms associated with farm-reared of tropical freshwater prawn.…”