There are no precedents concerning the quality of Octopus maya during chilled storage. This study evaluated the shelf life of the red octopus in chilling storage (4 o C) and the correlation of the sensory quality index with microbiological counting and the biochemical indicators (hypoxanthine, histamine and volatile amines). A total of 112 whole raw octopuses (average weight of 896 g) were randomly selected from seven batches and exposed to 4°C for 18, 24, 48, 72, 84, 96, and 100 h. The histamine concentration (91.7%), followed by the counts of psychrotrophic bacteria (5.5%) and hypoxanthine (2.2%), were the predictors from the redundancy analysis that better explained the changes taking place during the chilling hours. After 72 h of chilling, the microbial count was determined to be log 4.7 CFU/g, and the octopus samples were classified as B quality (minor sensory quality defects) based on the sensory quality scale. Although the samples were not classified as unacceptable at 100 h of refrigeration by the sensory index, the level of histamine reached the defect action level (5 mg/100 g) as ruled by the International Food Safety Authorities. The shelf life of the red octopus in chilling storage was predicted to be 119 h.

No abstract

Despite the increasing reports on the incidence of fresh vegetables and fruits as a possible vehicle for human pathogens, there is currently limited knowledge on the growth potential of Escherichia coli O157:H7 on different plant substrates. This study analyzed the selective adhesion and growth of E. coli O157:H7 on chili habanero (Capsicum chinense L.), cucumber (Cucumis sativus), radish (Raphanus sativus), tomato (Lycopersicon esculentum), beet (Beta vulgaris subsp. vulgaris), and onion (Allium cepa L.) under laboratory conditions. The Gompertz parameters were used to determine the growth kinetics. Scanning electron microscopy was used to visualize the adhesion of E. coli O157:H7 on the epicarp of the samples. Predictive models were constructed to compare the growth of E. coli O157:H7 on the samples with different intrinsic factors and to demonstrate the low selectivity of the pathogen. No significant difference was observed in the lag-phase duration (LPD), generation time (GT), and exponential growth rate (EGR) of the pathogen adhered to the samples. The interaction between the microorganism and the substrate was less supportive to the growth of E. coli O157:H7 for onion, whereas for tomato and cucumber, the time for the microorganism to attain the maximum growth rate (M) was significantly longer than that recorded for other samples.

No abstract

There are no precedents concerning the quality of Octopus maya during chilled storage. This study evaluated the shelf life of the red octopus in chilling storage (4oC) and the correlation of the sensory quality index with microbiological counting and the biochemical indicators (hypoxanthine, histamine and volatile amines). A total of 112 whole raw octopi (average weight of 896 g) were randomly selected from seven batches and exposed to 4°C for 18, 24, 48, 72, 84, 96, and 100 h. The histamine concentration (91.7%), followed by the counts of psychrotrophic bacteria (5.5%) and hypoxanthine (2.2%), were the predictors from the redundancy analysis that better explained the changes taking place during the chilling hours. After 72 h of chilling, the microbial count was determined to be log 4.7 CFU/g, and the octopus samples were classified as B quality (minor sensory quality defects) based on the sensory quality scale. Although the samples were not classified as unacceptable at 100 h of refrigeration by the sensory index, the level of histamine reached the defect action level (5 mg/100 g) as ruled by the International Food Safety Authorities. The shelf life of the red octopus in chilling storage was predicted to be 119 h.

No abstract

Heterotrophic bacteria (HB) play an important role in aquatic ecosystems as recyclers of dissolved organic matter (DOM). The objective of this study was to characterize the spectral characteristics of intracellular (IC), and extracellular (EC) compounds produced by 12 HB isolated from two aquaculture systems. Microorganisms belonging to the genera Bacillus, Paenibacillus, and Psychrobacillus were identified by analysis of the 16S ribosomal gene. Aliquots of bacterial culture were centrifugated every hour (1st to 7th) to obtain the EC compounds. The pellet was ultrasound-lysed to obtain the IC compounds. Excitation-emission matrices were used in combination with parallel factor analysis (PARAFAC) to characterize the fluorescent components of DOM (FDOM). PARAFAC indicated two protein-like components and two humic-like components in both cell spaces. At the IC, B. macquariensis showed a high fluorescence index (FI), probably associated with fulvic acid, quinones, or ketones. Psychrobacillus insolitus showed an inverse correlation between spectral slopes S275–295 and S350–400 in the EC and IC fractions, which may indicate differential release of low and high molecular weight molecules in these two fractions. The opposite occurred with B. licheniformis and P. alvei. The origin of FDOM in HB is an important finding of this work. The most significant amount of protein-like substances was produced at the IC level, with the humic- and fulvic-type at the EC. The main finding of this work is the evidence of differential production of humic-type or protein-type FDOM production by HB species from marine and freshwater aquaculture systems in their intracellular and extracellular fractions, as well different relative molecular weight. For aquaculture, these findings suggest that some bacterial species show promise in supplying essential amino acids to growing organisms, and others play a major role in nutrient exchange and the global carbon cycle.