The effect of curing agents (salt, glucose, nitrate, nitrite, and ascorbic acid) on the binding of skeletal peptides (carnosine and anserine) and a sarcoplasmic protein (myoglobin) with key flavor compounds (hexanal, octanal, 2-pentanone, 2-methylbutanal, and 3-methylbutanal) has been studied by solid-phase microextraction (SPME). Curing agents had an effect on the interaction process between carnosine and volatile compounds, which was higher than the interactions observed with anserine and myoglobin. Sodium chloride decreased the interaction of volatiles with carnosine except for octanal, which was increased, and 2-pentanone, which was unaltered. Ascorbic acid exerted the highest effect by decreasing the interaction of carnosine with all of the volatile compounds except for octanal and 2-pentanone. The interaction with anserine was affected by sodium chloride, nitrate, and nitrite, producing a decrease in the interaction with hexanal, octanal, and methional. Finally, sodium chloride, glucose, and nitrite increased the interaction of myoglobin with hexanal, octanal, and methional. The effect of simulated stages of the curing process on the binding was also studied. A combined effect of the curing agents resulted in a change in the relative proportions of volatile compounds that can lead to different flavor perceptions of dry-cured meat products.

Four strains of Dunaliella were grown at 25°C and pH 8±0.5, with continous illumination at 200 W/m(2). Their maximum specific growth rates ranged from 0.093 day(-1) to 0.234 day(-1), nitrate yields from 3.0 to 7.8 g cells/g NaNO3 and lipid contents from 3% to 6% of the dry wt, with carotenes 50 to 80% of the lipids. Of the carotenes, β-carotene made up 7 to 19%; all-trans-β-carotene 32 to 52% and 9-cis-β-carotene 29 to 55%. There are, therefore, considerable intra-specific differences between strains of Dunaliella.

The effect of endogenous dipeptides (carnosine and anserine) and peptidic fractions from meat extracts on aminopeptidase activity, alanyl and arginyl aminopeptidases purified from porcine skeletal muscle, was studied. Carnosine inhibited the activity ofporcine arginyl aminopeptidase (RAP); the inhibition being stronger with the purijied form of the enzyme than in the muscle extract. The RAP inhibition was competitive. One of the peptidic fractions isolated from meat extracts inhibited RAP activity but the degree of inhibition depended on the extent of purijcation. The major aminopeptidase present in muscle, alanyl aminopeptidase (AAP), was neither inhibited by natural dipeptides nor any of the peptidic fractions. The study of meat inhibitory peptides provides a better understanding of the action of proteolytic enzymes during meat processing.'Author for correspondence, Ph: 34 (96) 3900022, Fax: 34 (96) 3636301,