Rate of Deterioration of Freeze‐Dried Salmon as a Function of Relative Humidity

Abstract

SUMMARY— The rates of several deteriorative reactions, including lipid oxidation, astacene pigment loss, carbon dioxide production, and production of non‐enzymatic browning pigments, were studied in freeze‐dried salmon at 37°C and at several relative humidities. Results previously obtained in cellulosic model systems containing methyl linoleate were confirmed by data on oxygen absorption as a function of moisture content. Both the rate of the initial peroxide mono‐molecular decomposition and the peroxide value decreased as the water content was increased. Astacene pigment loss was reduced significantly by the higher moisture contents; non‐enzymatic browning was increased. The significance of the reactivity of water at low moisture contents was demonstrated by its effect on the various reactions.

How Apparent Digestibility of Carotenoids, Macronutrients, and Minerals are Differently Affected by Ration Level in Atlantic Salmon,Salmo Salar

“…It has been common practice to lyophilize feces samples for digestibility measurements, and high digestibility estimates (in particular >70%) and high variation have been reported for freeze-dried feces samples Choubert & Storebakken 1996;Page & Davies 2006). Low water activity renders carotenoids more susceptible to oxidation and degradation (Martinez & Labuza 1968;Goldman, Horev, & Saguy 1983;Jørgensen, Olsen, & Skibsted 1992), and freeze-drying of feces was therefore avoided in the present experiment. An isocratic HPLC system as described by Vecchi and colleagues (1987) was used to determine carotenoid concentrations of the plasma, feces, and feed samples.…”

Dehydration of food products A review

“…The literature on this topic is very extensive, although the interpretation of the data is often difficult-cf. Bate-Smith, Lea & Sharp (1943), Makower & Dehority (1943, Gane (1950), Gorling (1958), Stitt (1958), Salwin (1959), Taylor (1961), Charie, East & Vanderveen (1965), Labuza (1968) and Caurie (1970Caurie ( , 1971.…”

“…I t appears that for each product a moisture level has to be defined for which stability is achieved. Figures in the region of 2% are quoted although higher levels can be tolerated by some products (Acker, 1963a, b;Labuza, 1968;Salwin, 1962Salwin, , 1963Salwin, , 1959Saravacos & Stinchfield, 1965;Simatos, 1964;Simatos & Blond-Coste, 1967;Salwin & Slawson, 1959;Brockmann, 1966).…”

“…Oxygen scavengers such as glucose oxidase and hydrogen/palladium catalysts have been used but these increase the expense of packaging (Goldblith, Karel & Lusk, 1964;Bengtsson & Bengtsson, 1968). It has also been shown that the moisture level has a marked effect on the kinetics of the deteriorative reactions inasmuch as high moisture contents tend to retard lipid oxidation (Martinez & Labuza, 1968;Maloney et al, 1966; An important deteriorative reaction which has been widely studied is non-enzymic browning due to the Maillard reaction, which produces insoluble brown Polymeric compounds by the interaction of the carbonyl group of reducing sugars and the amino group of proteins and amino acids. Kluge & Heiss (1967) have studied in detail the reaction mechanism and kinetics of the browning reaction.…”

An equation for correlating equilibrium moisture content in foods

“…Several mathematical equations have been reported in the literature for describing water sorption isotherms of food materials (Henderson, 1952 ;Becker & Sallans, 1956 ; Day & Nelson, 1965;Strohman & Yoerger, 1967;Labuza, 1968;Ngoddy & BakkerArkema, 1970;Chen, 1971 ;Chen & Clayton, 1971). Eachofthemodels reported, empirical, semi-empirical or theoretical, have had some success in reproducing equilibrium moisture content data.…”