Quality characteristics of high salt fermented fish sauce (budu) produced using autochthonous Virgibacillus halodenitrificans PS21 and Staphylococcus simulans PMRS35

This study evaluated the effects of autochthonous starters on the quality characteristics of budu. The effects of individual or combined inoculation of Virgibacillus halodenitrificans PS21 and Staphylococcus simulans PMRS35 were compared to those of non-inoculation during 150 days of budu production. The starters directly affected characteristics of budu with browner colour and enhanced proteolysis and lipolysis as indicated by degree of hydrolysis and free fatty acid contents. The combined starter inoculation resulted in a high aspartic acid, glutamic acid and lysine levels. Additionally, key desirable volatiles, including 2-methylbutanal, 3-methylbutanal, benzaldehyde and 2-ethyl furan, were dominant in the starter-inoculated budu. In a sensorial analysis, the highest scores for appearance, colour, taste and flavour were assigned for inoculated budu with combined starters. Therefore, the addition of starters (V. halodenitrificans PS21 and S. simulans PMRS35) in budu production improved the quality characteristics and reduced the fermentation period.     

Synergistic antimicrobial effect of pyrophosphate on Listeria monocytogenes and Escherichia coli O157 in modified atmosphere packaged and refrigerated seabass slices

Effect of pyrophosphate (PP) in combination with modified atmosphere (MAP) (80% CO₂, 10% O₂ and 10% N₂) on the survival of Listeria monocytogenes and Escherichia coli O157 inoculated on seabass slices stored at 4 °C was investigated. PP pretreatment showed the synergistic effect on microbiological inhibition with MAP as evidenced by the lowered TVC and LAB counts, compared with samples stored in air and those kept under MAP. Microbiological changes of seabass slices inoculated with different levels of L. monocytogenes or E.coli O157 (10³ and 10⁵ cfu/g) were monitored during storage. PP pretreatment reduced colony count of E. coli O157 and extended the lag phase of L. monocytogenes. Therefore, MAP in combination with PP pretreatment not only retarded microbiological deterioration of seabass slices but also reduced or inactivated some pathogenic bacteria to some extent.     

Effect of turmeric and lemongrass essential oils and their mixture on quality changes of refrigerated green mussel (Perna viridis)

Effect of turmeric and lemongrass essential oils (Eos) and their mixture on quality of green mussel stored at 4 °C was investigated. The mixture of 0.25% turmeric and 0.25% lemongrass Eos could lower microbiological and chemical deterioration of mussel as evidenced by the lower microbial counts, total volatile base, ammonia, trichloroacetic acid‐soluble peptide contents and thiobarbituric acid‐reactive substances, compared with the control (P < 0.05). It indicated that a mixture of turmeric and lemongrass Eos in mussel showed synergistic effect on the retardation of bacterial growth and lipid oxidation. However, samples treated with 0.5% lemongrass oil exhibited the higher likeness score for odour and flavour, compared with the samples treated with other Eos throughout the storage of 15 days. Samples treated with turmeric essential oil caused the changes in odour and flavour. Therefore, lemongrass treatment was shown to be the promising means to prevent the deterioration and maintain the odour and flavour attributes of mussel during prolonged refrigerated storage.     

Collagen changes in refrigerated sea bass muscle treated with pyrophosphate and stored in modified- atmosphere packaging

Changes in collagen of sea bass muscle treated with and without pyrophosphate (PP) were monitored during storage in modified-atmosphere packaging (MAP) (80% CO₂, 10% O₂ and 10% N₂) at 4 °C. No changes in acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) of sea bass muscle with and without PP treatment were observed during storage in MAP up to 21 days. However, a slight decrease in insoluble collagen (ISC) of a sample kept in MAP was found. For sea bass muscle stored under an air atmosphere ASC increased, whereas PSC and ISC decreased with a concomitant loss in the firmness     

Shelf‐life extension of refrigerated seabass slices under modified atmosphere packaging

The effect of CO₂‐enriched atmosphere in combination with either oxygen or nitrogen on the keeping quality of seabass slices stored at 4 °C was investigated. The inhibitory effect on bacterial growth increased proportionally to the CO₂ concentration in the packaging, maximum inhibition being achieved with 100% CO₂ (P < 0.05). Seabass slices stored in CO₂‐enriched atmosphere had lower total volatile base, trimethylamine, ammonia and formaldehyde contents than those stored in air (P < 0.05). However, increases in lightness and exudate loss were observed for samples packaged in high‐CO₂ atmosphere, suggesting the denaturation of both muscle and pigment proteins by carbonic acid formed. Thiobarbituric acid‐reactive substances (TBARS) increased as the CO₂ concentration increased (P < 0.05). However, odour, flavour and overall acceptability of CO₂‐enriched packaged samples, particularly with 80 and 100% CO₂, were acceptable throughout storage for 21 days. Chemical and microbial changes in all samples were generally in agreement with sensory panel evaluations. The shelf‐life of seabass slices packaged in 80–100% CO₂ atmosphere could be extended to more than 20 days at 4 °C, compared with 9 days for those packaged in air. © 2002 Society of Chemical Industry