PRESERVATION OF BLUE-JACK MACKEREL (TRACHURUS PICTURATUS BOWDICH) SILAGE BY CHEMICAL AND FERMENTATIVE ACIDIFICATION |
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| Authors: | MARIA L.N. ENES DAPKEVICIUS M.J. ROBERT NOUT FRANK M. ROMBOUTS JACQUES H. HOUBEN |
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| Affiliation: | Center for Agricultural Technology Research (CITA-A) Department of Agricultural Science University of The Azores Terra Chã, 9701-851 Angra do Heroísmo, Azores, Portugal; Laboratory of Food Microbiology Wageningen University PO Box 8129, Wageningen, EV 6700, the Netherlands; Utrecht University IRAS, Public Health and Food Safety Division PO Box 80175, 3508 TD Utrecht, the Netherlands |
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| Abstract: | We compared acidified and lactic acid fermented silage approaches for the preservation of blue‐jack mackerel. Silages acidified with formic and propionic acids had stable pH (3.8) and low (19 mg/g N) levels of volatile nitrogen compounds (total volatile basic nitrogen, TVBN), but relatively high (82 g/100 g) final non‐protein‐nitrogen (NPN) values. The silage was fermented with Lactobacillus plantarum LU853, a homofermentative lactic acid bacterium with a high growth (0.51/h) and acidification rate at 37C (optimum temperature), able to grow in the presence of 40 g/L NaCl and to ferment sucrose and lactose. The silages at 37C reached safe pH < 4.5 values within 48–72 h, either (F2a) or not (F0), in combination with 20 g/kg salt addition; F2a acidified more rapidly, which may be an advantage for its microbiological stability. Proteolysis resulting in 53–59 g NPN/100 g N was lower in fermented than in acidified silages; however, in fermented silages, the levels of TVBN were much higher (50–80 mg TVBN/g N) than generally considered acceptable. |
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