ABSTRACT
Biogenic amines, total volatile base-nitrogen (TVB-N), and sensory evaluation are some of the indicators used for fish quality determination. Our objective was to evaluate the relationship among histamine, cadaverine, putrescine, TVB-N, and sensory evaluation as quality assessment tools. Two groups of six mahi-mahi fillets were refrigerated at 7 degrees C and sampled on days 0, 2, 4, 6, 8, and 10. On day 3, histamine, cadaverine, and putrescine levels reached 5, 3, and 0.5 mg/100 g, respectively, whereas TVB-N reached 30 mg/100 g. Sensory scores were 6 to 6.5 (10 very fresh and 1 very spoiled) for odor, appearance, texture, and color. Correlations were 0.78 and 0.72 between histamine and cadaverine and histamine and putrescine, 0.74 and 0.80 between TVB-N and cadaverine and TVB-N and putrescine, and 0.75 and 0.78 between odor and putrescine and odor and cadaverine. AromaMaps showed distinct trends for deteriorating mahi-mahi (Coryphaena hippurus) quality.
Subject(s)
Cold Temperature , Food Handling/methods , Food Preservation/methods , Seafood/analysis , Seafood/standards , Animals , Biogenic Amines/analysis , Cadaverine/analysis , Fishes , Histamine/analysis , Odorants/analysis , Putrescine/analysis , Quality Control , Taste , Time FactorsABSTRACT
The molecular events associated with susceptible plant responses to disease-causing organisms are not well understood. We have previously shown that ethylene-insensitive tomato plants infected with Xanthomonas campestris pv. vesicatoria have greatly reduced disease symptoms relative to wild-type cultivars. Here we show that salicylic acid (SA) is also an important component of the susceptible disease response. SA accumulates in infected wild-type tissues and is correlated with necrosis but does not accumulate in ethylene-insensitive plants. Exogenous feeding of SA to ethylene-deficient plants restores necrosis, indicating that reduced disease symptoms are associated with failure to accumulate SA. These results indicate a mechanism for co-ordination of phytohormone signals that together constitute a susceptible response to pathogens.
Subject(s)
Cell Death , Ethylenes/metabolism , Salicylic Acid/metabolism , Solanum lycopersicum/cytology , Xanthomonas campestris/physiology , Solanum lycopersicum/microbiology , Signal TransductionABSTRACT
Precolumn derivatization applying o-phthaldialdehyde (OPA) was used to analyze free lysine, histidine, and ornithine, precursors of the respective biogenic amines cadaverine, histamine, and putrescine, which are considered indicators of fish quality and safety. This method uses 75% methanol to eliminate the use of strong acids as the extraction solution. Each analysis took 35 min, was reproducible, and allowed separation of primary amino acids in fish samples. A binary solvent delivery system coupled with a fluorescence detector and an Ultrasphere ODS column were utilized for HPLC separation. Linearity of the calibration curves was very good (r(2) = 0.99) for the amino acids of interest. Minimum concentrations of detection were 40 pmol/mL for histidine and lysine and 70 pmol/mL for ornithine. Average recoveries were 72% for lysine, 93% for histidine, and 98% for ornithine. This method used solvent gradient elution to study the levels of these analytes in mahi-mahi, bigeye tuna, and flounder.
