Preliminary studies on applicability of volatile bases to evaluation of freshness of brine-salted herring
Kolakowski, E. | Tokarczyk, G. | Bednarczyk, B. | Dudzicz, M. | Przybylski, P.(Akademia Rolnicza, Szczecin (Poland). Katedra Technologii Zywnosci)
Applicability of total volatile bases (TVB), trimethylamine (TMA), and ammonium (NH3), assayed with the Conway method, to evaluation of the degree of freshness of brine-salted, headed and gutted Baltic herring ripened at 4 and 8 deg C was studied. The brine contained varying NaCl concentrations: from 8 to 14 percent (without additives) or 12 and 14 percent NaCl with addition of the following stimulants: acetic acid, calcium chloride, sugar, and Trilac lactic acid bacteria formula. The N-TMA content was found to characteristically decrease during ripening, particularly in those fish harvested in summer. The decrease contributed to an irregular course of changes in TVB and their limited applicability to evaluation of salted herring freshness. The TVB content in the salted herring meat, that had just become unsuitable for consumption, varied from 27 to 53 mg percent N. Changes in the ammonium content during ripening were more regular than those of TVB. The salted fish became unsuitable for consumption at about 22 mg percent N-NH3, but for herring ripened in acidified brine this value was higher (32 mg percent N-NH3). Other additives used with brine did not interfere with the regular changes of ammonium content, except for the high concentrations of calcium chloride (0.5 percent) and Trilac: at the initial phase of ripening (until day 6 to 9), the additives caused the NH3 contents to increase slightly, most probably as a result of the activity of endogenous transglutaminase and that of lactic acid bacteria, respectively. In conclusions authors are suggested that ammonium content be used as an ancillary objective indicator in evaluation of freshness of brine-salted Baltic herring
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