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Physicochemical characterisation of raw fish and stickwater from fish meal production
Author(s) -
del Valle José M,
Aguilera José M
Publication year - 1991
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740540314
Subject(s) - chemistry , solubility , particle size , raw material , fish meal , dry matter , suspended solids , population , viscosity , particle size distribution , fish <actinopterygii> , chromatography , dried fish , food science , fishery , zoology , materials science , wastewater , biology , organic chemistry , environmental engineering , demography , sociology , engineering , composite material
Chemical and microbiological properties of raw fish (RF) and chemical properties of stickwater (SW) samples were studied as a function of the staleness level of the fish. As time elapsed from fish capture increased, the microbial count in RF, volatile nitrogen content in RF and SW, and dissolved solids and dissolved protein in SW, increased. The apparent viscosity of SW increased as the temperature decreased and as the dry solids or suspended matter content increased. The size distribution of suspended particles in SW depended on the sample preparation technique, method used to measure particle size and whether the size distribution was expressed in terms of the weight or population of fractions. The average size (by weight) of suspended solids in SW was 2.5 μm as estimated by electronic counting. The solubility of protein in SW decreased when acid or alkali were added or thermal treatment (1 h at 90°C) applied. A minimal solubility point occurred near pH 5. The molecular weight of most dissolved proteins in SF was 3 kD. SF also contained a small proportion of 67 kD proteins. The significance of this basic characterisation study for the selection of improved processes for stickwater recovery is discussed.