Changes in Protein and Non-Protein Nitrogen Compounds during Fishmeal Processing—Identification of Unoptimized Processing Steps

Abstract

Quality changes of protein and non-protein nitrogen compounds during industrial fishmeal processing of fatty pelagic species (mackerel/herring rest material blend, MHB) and lean fish (whole blue whiting, BW) were studied to identify processing steps that require optimization to allow production of products for human consumption. Samples from protein-rich processing streams throughout the fishmeal production were analyzed for proximate composition, salt soluble protein content (SSP), biogenic amines (BA), total volatile basic nitrogen (TVB-N), trimethylamine (TMA), and dimethylamine (DMA). Mass flows throughout processing were balanced based on the total mass and proximate composition data. The quality of the final fishmeal products was highly dependent on the fish species being processed, indicating that the processes require optimization towards each raw material. The chemical composition changed in each processing step, resulting in different properties in each stream. Most of the non-protein nitrogen compounds (including BA, TVB-N, TMA, and DMA) followed the liquid streams. However, the concentrate contributed less than 20% to the produced fishmeal quantity. Mixing of this stream into the fishmeal processing again, as currently carried out, should thus be avoided. Furthermore, the cooking, separating, and drying steps should be optimized to improve the water and lipid separation and avoid the formation of undesired nitrogen compounds to produce higher-value products intended for human consumption.

Study of The Body Composition and Oxidation Indices in Some of Salmon Products Imported to Iraq

“…The amount of protein in fish muscles is affected by their moisture and fat content, as the percentage of protein is inversely related to the percentage of moisture and fat, and these percentages are not fixed because they vary based on age, size, feeding and fishing season, physical activity and sexual status [22]. The reasons for the difference in protein ratios in this study may be due to their influence by several factors, including the autolysis of protein by autoenzymes found in fish meat of various species and volatilization of quantities of volatile nitrogenous bases formed during transport and storage [23]. Furthermore, Hamilton et al [24] showed that the protein content in the muscles of Atlantic salmon ranges from 16-21.…”