Influence of spoilage and processing temperature on the quality of marine fish protein sources for salmonids

Abstract

Press cake meals were prepared from previously frozen herring immediately following thawing and after storage for 8 or 12 days at 2-5°C. Each of the raw sources of hemng was subjected to two processing temperatures, 75°C and 1OO"C, during meal preparation. Also, protein hydrolysates were prepared using ocean perch when fresh or after storage at 2-5°C for 4 or 8 days. Subsequently, each of the three hydrolysates was dried at 85°C or 93°C.In two separate experiments, each of the hemng press cake meals and dried perch protein hydrolysates was blended with a reference diet in a 30:70 ratio (test protein source: reference diet).All diets contained 5 g kg-' chromic oxide as an indigestible marker. The reference diet and all test diets were provided to satiation to chinook salmon in salt water and rainbow trout in fresh water, with digestibility of organic matter, protein and energy measured by difference. Digestibility of protein was also measured by the pH-stat and dilute pepsin solubility in vitro techniques.The results indicated that variation in processing temperature to a maximum of 100°C had little effect on digestibility of marine fish protein sources. By contrast, raw material storage for 8 days or more at 2-5°C prior to processing was found to reduce organic matter digestibility and sometimes nitrogen digestibility in salmonids. In vitro measures of digestibility were of little help in predicting the nutritive value of the test protein sources. Cadaverine level in herring press cake meal was shown to be a good indicator of spoilage in the raw material.

Evaluation of different protein sources for aquafeeds by an optimised pH‐stat system

“…Nevertheless, some authors suggest that pH-stat is not a valid method for the measurement of protein digestibility, because differences in the buffering capacity of proteins could interfere with the measurement of protein hydrolysis. 24,25 In this sense the determination of baselines can be used as an indicator of such buffering capacity. 26,27 The baseline consumption of alkali was highly variable and, in some samples, considerable, amounting to up to 35% of the total uptake of alkali during the enzymatic digestion period.…”

CHEMICAL AND NUTRITIONAL PROPERTIES OF PACIFIC OCEAN PERCH (SEBASTES ALUTUS) WHOLE FISH AND BY-PRODUCTS

“…(2002) reported the nutritional evaluation of selected by‐products including carp offal, fish frames from a number of marine species and trout offal. Clancy et al. (1995) made hydrolyzates from ocean perch stored for 0, 4 and 8 days and evaluated protein quality.…”

“…Gunasekera et al (2002) reported the nutritional evaluation of selected by-products including carp offal, fish frames from a number of marine species and trout offal. Clancy et al (1995) made hydrolyzates from ocean perch stored for 0, 4 and 8 days and evaluated protein quality. Digestibilities of fish processing by-products and fish meals have been reported by many investigators including feeding trials in trout and salmon by Sugiura et al (1998).…”

Nutritive values of low and high fibre canola meals for shrimp (Penaeus vannamei )

“…Various sources of fish meal are employed in marine shrimp diets because in general, they have high palatability and digestibility, excellent essential amino acid and fatty acid profiles, and high levels of available energy. However, fish meal quality may vary because of raw material spoilage and excessive Nutritive values of low and high fibre canola meals for shrimp (Penaeus vannamei) drying temperatures (> 100°C) during processing (McCallum & Higgs 1989;Pike et al 1990;Pike 1993;Clancy et al 1995). Also in some regions, the fish meal may contain different ratios of trash fish, small shrimp and other small aquatic animals (Penaflorida 1989).…”