Abstract
Lactic acid fermentation was evaluated as a method to preserve fish and chicken by-products. Herring (Clupea harengus) by-products (viscera and heads) and chicken by-products (heads, viscera, feathers, feet and discarded whole chickens) were minced, mixed with 5% dextrose and inoculated with 108 colony forming units (cfu)/g of four different lactic acid bacteria cultures. The by-product was fermented at 25°C and evaluated for pH, % produced lactic acid, redox potential and odour during four weeks' storage. In herring offal, pH decreased from 6.8 to 4.2 in one week and stabilized at about 4.3. In the same time, 2.0% to 3.2% lactic acid was produced and concentrations stabilized from 2.5% to 4.0%. In chicken offal, pH decreased to a stable level of 4.4, and 3.2% lactic acid was produced after one week of fermentation. A negative and stable redox potential was achieved after one week of fermentation in both herring and chicken offal.
Highlights
Animal by-products are obtained in feed plants in which the raw material is processed in different ways, depending on the origin and destinationof the feed
Promising results have been obtained in preserving fish and slaughter-house by-products with lactic acid bacteria (LAB) (Kangas and Kangas 1983,Lindgren and Pleje 1983, Hassan and Heath 1986, Tibbets et al 1987, Skrede and Nes 1988, Russel et al 1992, Urlings 1992)
Fast fermentation of herring offal with a rapid drop in pH to 4.4 or less resulted in a less putrefactive odour and a more stable silage than in silages produced at slower pH declines
Summary
Animal by-products are obtained in feed plants (pet food and fur animal feed) in which the raw material is processed in different ways, depending on the origin and destinationof the feed. With a suitable starter culture, a mixture of fish or slaughter by-products and carbohydrates may reach a pH of 4.4 to 5.0 in 24 to 48 h (Lindgren and Pleje 1983) Silage of this kind has been used as a component of feed for furbearing animals (Skrede and Nes 1988, Lassén et al 1990a, b, Urlings 1992) and pigs (Tibbets et al 1987, Partanen et al 1992) with varying results
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