Effect of pH on the physicochemical characteristics and the surface chemical composition of camel and bovine whey protein's powders.

This study investigated the effect of pH on the denaturation extent, the surface chemical composition, the water sorption isotherm and the glass transition temperature of camel and bovine whey protein's powders. The LC-MS analysis indicated that the ß-Lactoglobulin was the most denatured protein in bovine whey powders regardless the pH value, while this protein was totally absent in camel whey. The α-Lactalbumin was relatively heat stable after drying and predominated the powder surface (X-ray photoelectron spectroscopy results) in both camel and bovine whey powders regardless the pH (neutral (6.7) or acidic (4.3 and 4.6)). Analysis of the water sorption isotherms indicated that decreasing the pH induced the increase of the water activity of lactose crystallization for camel and bovine whey powders. Finally, decreasing the pH led to the decrease of the glass transition temperature of camel and bovine whey powder (at 0.13, 0.23, and 0.33 of water activity).

Incorporation of probiotic strain in raw minced beef meat: Study of textural modification, lipid and protein oxidation and color parameters during refrigerated storage.

The aim of this work was to evaluate the effect of different concentrations of probiotic strain Lactobacillus plantarum TN8 on the quality and safety of raw minced beef after 10 days of refrigerated storage. The obtained results showed that the incorporation of the probiotic strain can inhibit the proliferation of spoilage microorganisms, such Listeria monocytogenes and Salmonella spp., delay the lipid oxidation, improve texture parameters, and extend the shelf life of these products during storage. We also examined the correlations between protein and lipid oxidation, texture profile and color parameters of raw minced beef meat inoculated with L. plantarum TN8. The incorporation of strain at 108 CFU/g resulted in better quality inclusive color, lipid oxidative stability, and texture parameters notably cohesiveness, adhesiveness, hardness and chewiness. Overall, the findings demonstrated that TN8 can be used as a biopreservative agent for extending the safety and quality of refrigerated raw minced beef meat.

Quality Assessment of Fresh Meat from Several Species Based on Free Amino Acid and Biogenic Amine Contents during Chilled Storage.

This paper studies the changes that occur in free amino acid and biogenic amine contents of raw meats (beef, pork, lamb, chicken and turkey) during storage (2 °C, 10 days). The meat cuts samples were harvested from a retail outlet (without getting information on the animals involved) as the following: Beef leg (four muscles), pork leg (five muscles), lamb leg (seven muscles), turkey leg (four muscles), and chicken breast (one muscle). Meat composition varied according to meat types. In general, pH, microbiology counts, biogenic amine (BA), and free amino acid (FAA) contents were also affected by meat types and storage time (p < 0.05). Chicken and turkey presented the highest levels (p < 0.05) of FAAs. Total free amino acids (TFAA) were higher (p < 0.05) in white meats than in red ones. The behavior pattern, of the total free amino acids precursors (TFAAP) of Bas, was saw-toothed, mainly in chicken and turkey meat during storage, which limits their use as quality indexes. Spermidine and spermine contents were initially different among the meats. Putrescine was the most prevalent BA (p < 0.05) irrespective of species. In general, chicken and turkey contained the highest (p < 0.05) levels of BAs, and TFAAP of BAs. In terms of the biogenic amine index (BAI), the quality of chicken was the worst while beef meat was the only sample whose quality remained acceptable through the study. This BAI seems to be more suitable as a quality index for white meat freshness than for red meat, especially for beef.

Toward the enhancement of sensory profile of sausage "Merguez" with chickpea protein concentrate.

The influence of different Chickpea Protein Concentrates (CPC) addition at different levels (CPC: 1.5, 2.5 and 5% (w/w)) on physico-chemical, textural and hedonic properties of formulated and cooked sausage "Merguez" were investigated. The obtained results exhibited that CPC addition increased protein content of "Merguez" sausage and improved the process yield. Significant differences were noticed on the cooking loss and textural properties for "Merguez" sausages formulated with 5% of CPC compared to the control (p < 0.05). Hedonic analysis showed that protein addition had no significant effect on sausages taste. However, sausage texture and global acceptability were markedly improved (p < 0.05). These results suggest that CPC could be an important alternative source of protein additive for the improvement of the physico-chemical, textural and sensorial properties of meat sausages.

A Comparative Study on Formation of Polar Components, Fatty Acids and Sterols during Frying of Refined Olive Pomace Oil Pure and Its Blend Coconut Oil.

The frying performance of pure refined olive-pomace oil (ROPO) and blended with refined coconut oil (RCO) (80:20) was compared during a frying operation of French fries at 180 °C. Blending polyunsaturated oils with highly saturated or monounsaturated oils has been studied extensively, however in literature there is no study has been reported so far on blending ROPO (rich in monounsaturated fatty acids) with RCO (rich in saturated fatty acids) to formulate new frying oils. At the end of the frying process, the blend of ROPO/RCO exhibited a higher chemical stability than the pure ROPO based on total polar compounds (TPC), and polymers. The rate of TPC formation was achieved 23.3% and 30.6% for the blend and the pure oil, respectively. Trans and free fatty acids content, as well as anisidine value were also observed to be the highest in the pure ROPO. This study evaluated the frying performance in the search for appropriate frying oils to deliver healthy fried products with optimized nutritional qualities.

Physicochemical, techno-functional, and antioxidant properties of a novel bacterial exopolysaccharide in cooked beef sausage.

This work investigates the effects of partial replacement of vitamin C (Vit C) with a purified exopolysaccharide (EPS-Ca6) produced by Lactobacillus sp. Ca6, on the antioxidant activities of cooked beef sausages during refrigerated storage. The physicochemical, techno-functional and viscosity properties of EPS-Ca6 were also studied. Functional properties of EPS-Ca6 were determined based on Water Holding Capacity (WHC), Oil Holding Capacity (OHC), emulsification activity, and foaming ability. EPS-Ca6 demonstrated excellent emulsifying and emulsion stabilizing properties. It was able to emulsify several food-grade oils and hydrophobic compounds, particularly corn oil and diesel with emulsification indexes of 90 and 100%, respectively at a concentration of 0.5%. The effect of EPS-Ca6 on oxidative processes in cooked beef sausages during storage up to 12days at 4°C was evaluated. The obtained results showed a high rate (p<0.05) of oxymyoglobin (OxyMb) and low lipid oxidation. Overall, our findings provided evidence that EPS-Ca6 could be used as a natural additive for maintaining storage stability of cooked beef sausages, and could replace synthetic polymer in several industrial applications.

Evaluation of dermal wound healing activity and in vitro antibacterial and antioxidant activities of a new exopolysaccharide produced by Lactobacillus sp.Ca6.

The present study aimed to evaluate the in vitro antibacterial and antioxidant activities and the in vivo wound healing performance of a noval exopolysaccharides (EPS-Ca6) produced by Lactobacillus sp.Ca6 strain. The results showed that EPS-Ca6 had a potential antioxidant activity determined through four different assays: DPPH scavenging activity, reducing power, ß-carotene bleaching by linoleic acid assay, and Metal chelating activities. It also exhibited significant antibacterial activity against pathogenic bacteria Salmonella enterica and Micrococcus luteus. The wound healing activity of the EPS-Ca6, using excision wound model in rats, showed that this novel EPS accelerated significantly wound healing activity as compared to the control group, and a total closure was achieved after 14days of wound induction. Furthermore, histological examination of biopsies showed fully re-epithelialized wound with a complete epidermal regeneration. Overall the finding indicates that the EPS-Ca6 might be useful as a wound healing agent in modern medicine.

Structure, functional and antioxidant properties in Tunisian beef sausage of a novel polysaccharide from Trigonella foenum-graecum seeds.

A novel polysaccharide named Fenugreek Water-Soluble Polysaccharide (FWSP), consisting of a gluconic acid polymer, was isolated from fenugreek seeds. It was structurally characterized by Fourier transformed infrared (FT-IR), X-ray diffraction (XRD), High performance liquid chromatograpy (HPLC), and Nuclear magnetic resonance (NMR) spectroscopies. FT-IR and NMR spectra showed the characteristic bands of polysaccharides. According to XRD spectrum, FWSP is a semi-crystalline polymer. Functional properties of FWSP were investigated based on Water Holding Capacity (WHC), Oil Holding Capacity (OHC), emulsification activity, and foaming ability. FWSP was capable of emulsifying several food-grade oils and hydrophobic compounds, especially corn oil and hexane. The effects of FWSP on oxidative processes in beef sausages during refrigerated (4°C) storage was investigated. The results showed significant inhibition (p<0.05) of lipid and myoglobin oxidation and provided evidence that FWSP is a potent and useful antioxidant for maintaining storage stability of beef sausages, and could replace vitamin C currently used as antioxidant in industry process.

Extraction, partial purification and characterization of amylase from parthenocarpic date (Phoenix dactylifera): effect on cake quality.

BACKGROUND: Phoenix dactylifera L. plays an important role in social, economic and ecological Tunisian sectors. Some date palms produce parthenocarpic fruit named Sish. The objective of the present study was to extract biomolecules from parthenocarpic fruit by producing value-added products from the fruits. RESULTS: The extraction of amylolytic activity from parthenocarpic fruit (AmyPF) was optimized using Box-Behnken design (BBD). Partial purification of about 250-fold with an activity yield of 47% was achieved. The amylase exhibited a specific activity of 80 U mg-1 protein. The optimum pH and temperature for enzyme activity were 5 and 55 °C respectively. The enzyme was highly active over a wide range of pH (5-10), and significant stabilization was observed at 60 °C. The purified enzyme belongs to the exo type of amylases. Given the economic and industrial relevance of amylases used in the food industry, three different concentrations of AmyPF (0.007, 0.014 and 0.018 U g-1 ) were incorporated into a cake formulation, resulting in a decrease in density, moisture retention and water activity and an increase in hardness. CONCLUSION: The beneficial effect of AmyPF on the technological characteristics of cakes was confirmed by sensory evaluation. © 2017 Society of Chemical Industry.

Antioxidant and hemolytic activities, and effects in rat cutaneous wound healing of a novel polysaccharide from fenugreek (Trigonella foenum-graecum) seeds.

The aim of this work was to evaluate the antioxidant and hemolytic activities as well as the in vivo wound healing performance of a novel polysaccharide (FWEP) extracted from fenugreek (Trigonella foenum-graecum) seeds. The antioxidant activity was evaluated in vivo and in vitro using various assays. Results showed that FWEP exhibited strong antioxidant activities but no hemolytic activity was observed towards bovine erythrocytes. The application of FWEP hydrogel on the wound site in a rat model enhanced significantly wound healing activity and accelerated the wound closure after 14days of wound induction. Histological examination also demonstrated fully re-epithelialized wound with a complete epidermal regeneration. Altogether, these evidences demonstrated that FWEP had strong wound healing potential presumably achieved through its antioxidant activities.

Storage stability of low-fat sodium reduced fresh merguez sausage prepared with olive oil in konjac gel matrix.

This paper evaluates the nutritional values and stability during refrigerated storage of fresh beef merguez sausage as affected by a reformulation process which modified the fat content both by reducing fat (replacing beef fat with konjac gel) and incorporating olive oil (replacing beef fat with olive oil stabilized in a konjac matrix) and by reducing sodium content, replacing sodium chloride with a salt mixture (containing potassium chloride, calcium chloride and magnesium chloride). A preservative (sodium metabisulphite) was also used to extend the shelf-life of the product. The fat was reduced by 32 to 80% and sodium by over 36%. The reformulation did not negatively affect the sensory evaluation. Low microbiota growth rate and biogenic amines were attributed mainly to the presence of sodium metabisulphite. This preservative could be used in the reformulation to enhance safety and/or extend the shelf-life of this type of product.

Biogenic amines in low- and reduced-fat dry fermented sausages formulated with konjac gel.

Biogenic amines in low- and reduced-fat dry fermented sausages made with konjac gel (KG) as pork backfat replacer were studied. An increase (P < 0.05) was observed in the microbial count during the fermentation process, reaching levels of over 8 Log cfu/g of total viable microorganisms and lactic acid bacteria. However, no significant differences were observed in the microbiota evolution as a function of the reformulation process (fat and konjac gel content). High levels of physiological amines (spermidine, spermine, and agmatine) were observed in the raw material. From day 2 of the fermentation process an increase (P < 0.05) was observed in tyramine and putrescine, which were the predominant amines at the end of the storage period. The increase in these amines was proportional to the presence of KG and fat reduction. This can also be seen for spermine, with agmatine showing the inverse. The biogenic amine levels in these products reformulated with KG are not considered to pose a health risk to consumers.

Low-fat frankfurters formulated with a healthier lipid combination as functional ingredient: microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation.

Oil (healthier lipid combination of olive, linseed and fish oils)-in-water emulsions stabilized with different protein systems (prepared with sodium caseinate (SC), soy protein isolate (SPI), and microbial transglutaminase (MTG)) were used as pork backfat replacers in low-fat frankfurters. Microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation of frankfurters were analyzed and found to be affected by the type of oil-in-water emulsion and by chilling storage (2° C, 41 days). Although the lipid oxidation levels attained were low, replacement of animal fat by healthier oil combinations in frankfurter formulation did promote a slight increase in lipid oxidation. Residual nitrite was affected (P < 0.05) by formulation and storage. Only 51-61% of the added nitrite was detectable in the product after processing and 17-46% at the end of storage. The microbial population was low in all formulations during chilling storage. Spermine was the most abundant amine (19-20 mg/kg), but similar in level to all samples.