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The present study was conducted to compare the antibacterial activity of oven‐dried and freeze‐dried Allium sativum along with its spray‐dried microencapsulated essential oil in the preservation of minced beef meat. Allium sativum extracts were tested against mesophilic aerobic microorganisms, coagulase‐positive staphylococci, Escherichia coli, Salmonella sp., and the sulfite‐reducing anaerobes. A difference between the chemical compositions of powders obtained by the conventional oven‐drying and freeze‐drying has been verified by HPLC‐MS2, freeze‐dried fresh garlic powder contains 74% of allicin, and 12% cysteine sulfoxides comparing to the oven‐drying garlic powder in which is detected two thiosulfinate isomers: allicin (67%) and allyl‐1‐propenyl thiosulfinate (21%). CIELAB color analysis was performed to assess the effect of drying temperature on powders. The microflora‐inhibiting effect of freeze‐dried fresh garlic and the spray‐dried microencapsulated essential oil at a concentration of 20% represents a promising way to be used in food systems such as meat and meat products preservation, at 4–8°C.

 The aim of the study is to establish some nutritional properties of garlic cultivated in Tunisia and to evaluate the antioxidant and the antimicrobial activites of its essential oil and ethanol extract. Tunisian garlic (Allium sativum) was characterized for moisture, ash and protein contents which were determined as 66%, 1.4% and 5.2% respectively. In addition, Fe (5.90 mg/kg), Cu (1.61 mg/kg), Mg (15 mg/kg) and P (140 mg/kg) were reported such as the major minerals in garlic. The fat profile of tunisian garlic was conducted, the main fatty acids identified were lauric acid (49.3%) and linoleic acid (20.4%). Essential oil obtained from A. sativum was analysed by capillary GCMS. Diallyl disulfide (49.1%) and diallyl trisulfide (30.38%) were the main components of the five identified components. The phenolic content of the ethanol extract are analysed for its phenolic profiles, colorimetric analysis revealed that the total phenols, flavonoids and proanthocyanidins contents were respectively 43.63 mg GA/g, 13.18 mg quercetin/g and 24.24 mg of catechin/g. Antioxidant activity was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, essential oil presented the highest antioxidant activity compared to its ethanol extract. IC50 values observed for the essential oil and ethanol extract were 300 μg/ml and 600 μg/ml respectively. The essential oil and ethanol extract from raw garlic were tested for antimicrobial activity against seven microorganisms. The results showed that ethanol extract was active against all tested strains: Escherichia coli, Salmonella typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes, Yersinia enterocolitica and Bacillus cereus.

The influence of temperature and time of heating on the production and composition of organosulfur compounds (OSC) in Allium sativum were investigated in a two-level design with two factors. The organosulfur compounds were identified by Headspace-GC-MS. It was established that temperature plays an important role in the regulation of the production of monosulfides and trisulfides. The effect of both negative and positive temperatures on the production and decomposition of OSC were showed. Although, monosulfides and trisulfides were totally absent at the beginning of incubation, several mono-and trisulfides were detected in high proportions at 120°C, during the 30 minutes incubation period. It appears that high temperature reduces the amount of disulfides, which are converted to monosulfides and trisulfides.