Naourez Ktari

Comparative Study on Biochemical Properties and Antioxidative Activity of Cuttlefish (Sepia officinalis) Protein Hydrolysates Produced by Alcalase and Bacillus licheniformis NH1 Proteases.

Antioxidative activities and biochemical properties of protein hydrolysates prepared from cuttlefish (Sepia officinalis) using Alcalase 2.4 L and Bacillus licheniformis NH1 proteases with different degrees of hydrolysis (DH) were determined. For the biochemical properties, hydrolysis by both enzymes increased protein solubility to above 75% over a wide pH range. The antioxidant activities of cuttlefish protein hydrolysates (CPHs) increase with increasing DH. In addition, all CPHs exhibited antioxidative activity in a concentration-dependent manner. NH1-CPHs generally showed greater antioxidative activity than Alcalase protein hydrolysates (P < 0.05) as indicated by the higher 1,1-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity and ferrous chelating activity. Both Alcalase and NH1 protein hydrolysates were able to retard lipid peroxidation and β-carotene-linoleic acid oxidation. Alcalase-CPH (DH = 12.5%) and NH1-CPH (DH = 15%) contained 75.36% and 80.11% protein, respectively, with histidine and arginine as the major amino acids, followed by glutamic acid/glutamine, serine, lysine, and leucine. In addition, CPHs have a high percentage of essential amino acids made up 48.85% and 50.04%. Cuttlefish muscle protein hydrolysates had a high nutritional value and could be used as supplement to poorly balanced dietary proteins.

Using Barley Beta Glucan, Citrus, and Carrot Fibers as a Meat Substitute in Turkey Meat Sausages and Their Effects on Sensory Characteristics and Properties

This study was aimed to evaluate the effect of addition of two levels (1% and 2%) of Barley Beta Glucan (BBG), citrus (Ceamfibre 7000), and carrot (ID809) fibers on chemical, sensorial properties, oxidation and microbial quality of turkey meat sausage, during 21 days of storage at 4°C. The findings indicated that the addition of the three fibers decreased fat and protein contents but increased moisture content. Color parameters were significantly (p<0.05) affected by the fiber type and content. The meat substitution resulted in a tendency toward lighter coloration. A significant progression in the textural hardness, elasticity and chewiness of fiber-added sausages, was observed. The addition of the three fibers, at 1% and 2% level, induced a decrease in hardness when compared to control. Furthermore, color, taste, flavor and overall acceptability attributes were similar to the control when the fibers were incorporated. According to sensorial evaluations, the three polysaccharides remained at 1% to the consumer acceptability of sausage. Besides, the addition of the three polysaccharides had a significant effect on sausage safety because of its reduction of the lipid oxidation degree monitored by TBARS and it had no effect on microbial proliferation. Overall, the results of this study indicate that the three polysaccharides can be applied at 1% in turkey meat sausage to increase their nutritional status whilst maintaining the quality and safety attributes of the product.

Effects of Cooking Methods on Physicochemical and MicrobiologicalCharacteristics of Zebra Blenny (Salaria basilisca) Fillets

This study was undertaken to determine the effects of two appropriate household cooking methods, steam and microwave-cooking, on proximate chemical composition, energetic values, fatty acids profiles, texture profile analysis and bacteriological characteristics of zebra blenny (Salaria basilisca) fillets from Tunisian coasts. The nutritional values of the fish fillets were improved after the two cooking methods. Fatty acid profiles of zebra blenny fillets showed that Polyunsaturated Fatty Acids (PUFA) contents are higher than those of Saturated Fatty Acids (SFA). They showed also differences between cooking methods. All textural attributes of zebra blenny fillets were influenced by cooking process. Microbiological changes [Total viable counts (TVC), Lactic Acid Bacteria (LAB), Enterobacteriaceae, Listeria monocytogenes as well as fungi] were monitored as a function of treatment and storage time. On day 5 of storage under refrigeration the number of micro-organisms is always minimal for samples heat treated comparing with those raw.