Assessment of the Anti-Microbial Activity of Dried Garlic Powders Produced by Different Methods of Drying

Effects of Ginger and Garlic Powders on the Physicochemical and Microbiological Characteristics of Fruit Juices during Storage

Natural preservatives such as garlic and ginger can be added to the formulation of fresh fruit juices to encourage the consumption of health-promoting foods. In this study, the influence of garlic and ginger and the storage conditions on physicochemical and microbiological characteristics of fruit juices were investigated. The fruit juice assortments were produced from apple, apple and pumpkin, and apple and pomegranate and were treated with 0.5 g garlic powder, 0.5 g ginger powder, and 0.25 g mix of garlic and ginger powders. A total of 12 unpasteurized samples were produced, of which 3 were control samples. Samples stored at 20 and 4 °C were analyzed at 0, 3, 6, and 9 days for water activity (aw), pH, titratable acidity (TA), total soluble solids (TSS), electrical conductivity (EC), vitamin C, color parameters, total number of germs, yeasts, and molds, Listeria, Enterobacteriaceae, and Escherichia coli. Results showed that aw, pH, TSS, and vitamin C content decreased during storage of fruit juice samples, while TA increased. The lowest increase in total number of aerobic mesophilic germs was determined for the apple and pumpkin juice with garlic and ginger and apple juice with garlic.

Freeze-dried, oven-dried, and microencapsulation of essential oil from Allium sativum as potential preservative agents of minced meat

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.

Characteristics, biosynthesis, decomposition, metabolism and functions of the garlic odour precursor, S-allyl-L-cysteine sulfoxide

S-Allyl-L-cysteine sulfoxide (ACSO) is an odour precursor in garlic bulbs. One plausible pathway for the biosynthesis of ACSO involves S-2-carboxypropyl glutathione produced from glutathione and methacrylic acid via valine or from γ-glutamyl cysteine. The elimination of glycine and glutamic acid from S-2-carboxypropyl glutathione produces S-2-carboxypropyl cysteine, which is converted to S-allyl cysteine by decarboxylation and oxidation. S-Allyl cysteine is also biosynthesized via the elimination of glutamic acid from γ-glutamyl S-allyl cysteine by γ-glutamyl transpeptidase. The sulfur oxidation of S-allyl cysteine by flavin-containing monooxygenase forms ACSO. When cells are damaged by slicing or grating, ACSO in the cytoplasm or cytoplasmic vesicle is immediately converted to allylsulfenic acid, pyruvic acid, and ammonia by alliinase (C-S lyase), which is located in the vacuoles of vascular bundle sheath cells. Two molecules of allylsulfenic acid form diallyl thiosulfinate (allicin), which exhibits potent antimicrobial activity. Allicin eventually yields garlic odour compounds, such as diallyl disulfide (DADS) and diallyl trisulfide (DATS). Although these sulfides are known to exert various physiological functions, their strong odour limits their use in foods. On the other hand, ACSO is water-soluble and odourless and enhances sweet, salty, and umami tastes, characteristics of which are desirable for food additives. Upon consumption, ACSO is primarily absorbed from the small intestine in the intact form, but is also partly decomposed to allylsulfenic acid, pyruvic acid and ammonia. Allylsulfenic acid is then further converted to DADS and diallyl monosulfide (DAS). ACSO has numerous in vivo functions, such as the prevention of diabetes, myocardial ischaemia, hepatic injury, platelet aggregation and blood ethanol elevation. Although some of these effects may be attributed to its metabolites, ACSO itself contributes to many of these physiological functions.

Antibacterial and Antifungal Activities of Spices

Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices-such as clove, oregano, thyme, cinnamon, and cumin-possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens, pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives.