The aim of this study was to determine the physicochemical, microbiological, and sensory properti... more The aim of this study was to determine the physicochemical, microbiological, and sensory properties as well as shelf life of fresh mozzarella cheese samples. Fresh mozzarella cheese samples were packaged under five different Modified Atmospheres (MAP): Vacuum (Atm 2), 40% CO2/60% N2 (Atm 3), 60% CO2/40% N2 (Atm 4), 100% CO2 (Atm 5) and 100% N2 (Atm 6). Identical cheese samples were packaged in air (Atm 1), taken as the control. All cheese samples were kept under refrigeration (4±1°C) for 6 weeks. Atm 5 gas mixture was the most effective for inhibiting aerobic microflora growth in cheese samples stored at 4°C during 6 weeks. Lactic acid bacteria were not affected by CO2 presence even in high concentrations. Yeasts and moulds were totally inhibited by Atm 5 gas mixture throughout the entire storage period. Sensory evaluation showed that cheese packaged under Atm 3 retained good sensory characteristics for 6 weeks of storage while control samples were appreciated the least. Atm 5 provided the best shelf life extension at 4°C by 81 days, compared to the control.
The objective of this paper was to study the effect of milk fat substitution by (W 1 /O/W 2) mult... more The objective of this paper was to study the effect of milk fat substitution by (W 1 /O/W 2) multiple emulsions based on olive oil in comparison with full and low-fat milks on milk behavior during rennet coagulation. Therefore, based on the turbidimetric and conductivimetric methods, a follow up of enzymatic coagulation is realized. Drainage of renneted gels was followed by syneresis study and cheese yield. The comparison between the coagulation aptitude of low fat milk and milk-olive oil emulsion showed that the hydrolysis phase extended up to 35 minutes for full fat milk and up to 38 minutes for milk-olive oil emulsion. The transition phase solid/gel was shorter in the case of the whole milk. The reticulation phase was shorter in the case of milk-olive oil emulsion. The milk conductivity depended on the milk richness in fat content. Milk-olive oil emulsion showed the lowest cheese-making yield compared to its full and low-fat counterpart.
Physicochemical, sensory and coagulation properties of dromedary and cows’ skim milk white brined cheeses
International Dairy Journal, Jun 1, 2021
Abstract The coagulation of dromedary and cows' skim milk using camel chymosin was evaluated.... more Abstract The coagulation of dromedary and cows' skim milk using camel chymosin was evaluated. Milk coagulation was monitored using viscosimetric and conductometric techniques. Syneresis and cheese yield were also assessed. The proximate composition, colour, texture and sensory properties of the cheeses obtained were investigated over 7 days storage. The initial viscosity value was higher for cows' skim milk than for dromedary skim milk. Dromedary skim milk had substantially longer coagulation time (about 72.3 min) than cows' skim milk (about 27.5 min). Dromedary skim milk gel had lower syneresis percentage and moisture content with higher cheese yield. pH values of white brined cheeses decreased during storage with lower values for dromedary skim milk cheeses. Hardness of cheeses increased during storage with higher values for cows' skim milk cheeses. Regardless of storage day, dromedary skim milk cheeses were more acceptable than cows’ skim milk cheeses as evaluated by sensory panellists.
Characterization of nettle leaves (Urtica dioica) as a novel source of protease for clotting dromedary milk by non-destructive methods
Colloids and Surfaces B: Biointerfaces, Mar 1, 2022
This study investigates the valorization of the nettle leaves (Urtica dioica) as a novel source o... more This study investigates the valorization of the nettle leaves (Urtica dioica) as a novel source of a protease for clotting dromedary milk. The aim of this work is to study the effect of extracting pH on the enzymatic activity of nettle leaves extracts. The extraction was achieved in phosphate citrate buffer at different pH values (from 3 to 6.5) and the obtained extracts were used to coagulate dromedary milk. The characterization of the obtained extracts was carried out using non-destructive methods namely FT-MIR, fluorescence spectroscopy and turbiscan instrument. The extract prepared at pH = 4 had the highest proteolytic activity. The fluorescence and turbiscan measurements revealed a substantial effect of the pH value on chlorophyll residues extraction and stability, respectively. At an acidic environment (pH range of 3 - 4), the enzymatic extracts were unstable (with turbiscan stability index (TSI) values ~ 20), while at a nearly neutral pH value (pH range of 5 - 6.5), they were found to be more stable as indicated by the low TSI values ~ 1. The maximum milk-clotting activity (MCA) (0.021 U/mL) was obtained for the extracts prepared at pH = 4.
Journal of Food Science and Technology, Jan 21, 2015
The objective of this paper is to study the effect of milk-fat replacement on Gouda cheeses compo... more The objective of this paper is to study the effect of milk-fat replacement on Gouda cheeses composition, lipolysis and sensory characteristics. A Gouda cheese-like product was prepared from the substitution of milk fat with emulsified olive oil. For comparison, the low-fat variant without fat replacers and the full-fat cheese were also studied. Milk samples are initially pasteurized at 72°C for 3 s, cooled to 35°C, and added with 0.016 g L −1 of lactic ferments and 0.30 mL L −1 of microbial rennet. Total solids content was lower in cheeses containing fat replacers than in full and low-fat control cheeses due to the higher water-binding capacity of fat replacers. Free fatty acids rates were the highest in the case of reduced fat cheese-like product. The full-fat cheese showed a significantly higher overall impression score than all low-fat products.
Journal of Food Processing and Preservation, Sep 29, 2021
Effect of storage conditions on the physicochemical characteristics of edible films based on whey... more Effect of storage conditions on the physicochemical characteristics of edible films based on whey protein concentrate and liquid smoke,
Using a developed laboratory scale device, different heat treatment conditions were applied on ca... more Using a developed laboratory scale device, different heat treatment conditions were applied on camel and cow wheys. After each deposition experiment, photos of stainless steel plates were taken and dry deposit weights were determined. Proteins denaturation was studied by electrophoresis (SDS-PAGE) and differential scanning calorimetry (DSC). The obtained results have shown that heating both cow and camel wheys at 60 • C does not generate deposit. Furthermore, the heat treatment at above 70 • C was found to cause a severe fouling of stainless steel plate. The electrophoresis patterns indicated that heating at 90 • C caused camel serum albumin's (CSA) band disappearance for both rennet and acid wheys. However, ␣-lactalbumin's (␣-la) concentration decreased versus temperature and heating time. DSC thermograms showed that denaturation temperatures were 73.8 • C for camel rennet whey, 60.5 • C for camel acid whey, 70.5 • C for cow rennet whey and 63.9 • C for cow acid whey. Taken into the count the absence of -lg in camel milk and based on the obtained results several hypotheses were advanced to explain camel milk fouling during heat treatment.
Optimization of gluten‐free sponge cake fortified with whey protein concentrate using mixture design methodology
Food Chemistry, 2021
This study aimed to optimize mixtures of whey protein concentrate (WPC) and two flours of rice an... more This study aimed to optimize mixtures of whey protein concentrate (WPC) and two flours of rice and maize flours for the production of gluten-free sponge cakes. This was obtained by using mixture design methodology. WPC incorporation had positive effects on specific volume and baking loss of cakes, whilst, their incorporation increased their hardness. Considering all cakes properties, two formulas F1 (78.5% Maize, 15% Rice and 6.5% WPC) and F2 (82.4% Maize, 12% Rice and 5.6% WPC) were optimized using a mixture design. The microstructure F1 was more organized and very well structured with smaller aggregates. According to the organoleptic evaluation, F1 was also most appreciated by the tasting panel. The findings of the present study indicated that maize and rice flours, and WPC could be used as a substitute for wheat flour in producing sponge cakes of high quality.
A total number of 60 samples from traditional fermented milk “Rayeb” was randomly collected from ... more A total number of 60 samples from traditional fermented milk “Rayeb” was randomly collected from different localities in Sfax governorate, Tunisia and subjected to determination of pH, sensory evaluation and determination of total yeast and mold count, Coliforms count, total staphylococcal count, Staphylococcus aureus count and detection of Salmonella. The obtained results revealed that pH was ranged from 3.8 to 4.7, 40 out of 60 samples (66.67 %) had the grade good in sensory evaluation, the mean yeast and mold count was 1.34×107± 2262054 CFU/mL, the mean coliforms count was 3.707×103 ± 1510 CFU/mL. the mean count of total staphylococci was 5.10×103 ± 1257 CFU/mL, the mean S. aureus count was 68.4 ± 13 CFU/ mL. The incidence of pathogens in fermented foods, as highlighted in this study suggests that measures that minimize the risk of food-borne illnesses should be taken. The application of Hazard Analysis and Critical Control Point (HACCP) as advocated by the WHO should be applied ...
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