Ghassan Issa

Microbiological and chemical quality of tahini halva

Purpose – This paper aims to determine the microbiological and chemical quality of halva samples obtained from retail markets and producers in the Marmara region.Design/methodology/approach – Halva samples (120) were collected at intervals between March 2007 and February 2008. Samples were investigated for the microbiological (aerobic bacteria, Staphylococcus aureus, coliform bacteria, Escherichia coli, molds/yeasts, Salmonella spp. and staphylococcal enterotoxins) and chemical (sesame oil, protein, moisture, ash content, tahini, acidity, total sugar content and peroxide values) quality.Findings – Overall, 36.66 per cent (44/120) tahini halva samples were of unacceptable quality based on recommended criteria of microbiological (39 of 120, 32.5 per cent) and chemical quality (21 of 120, 17.5 per cent) by the Turkish Food Codex. Salmonella spp. and staphylococcal enterotoxins were not determined in the samples.Originality/value – Tahini halva, which is one of the oldest traditional desserts and is popular i...

Effect of rosemary essential oil and modified-atmosphere packaging (MAP) on meat quality and survival of pathogens in poultry fillets

The effect of rosemary (Rosmarinus officinalis L.) essential oil (REO) and modified-atmosphere packaging (MAP) on the survival of certain pathogens (Salmonella Typhimurium and Listeria monocytogenes) in poultry fillets and on their meat quality during 7 days of refrigerated storage were investigated. Because REO at 0.05% and 0.1% had weak antibacterial activity and REO at 0.3%, 0.5% and 1.0% imparted unacceptable organoleptic properties, only REO at 0.2% was used to treat the poultry meat. The results showed that adding 0.2% REO to poultry fillets did not reduce the size of the population of S. Typhimurium and L. monocytogenes. However, REO treatment significantly decreased the L* (lightness) value and increased the a* (redness) value of stored fillets, and adding REO in combination with MAP reduced the level of lipid oxidation. In conclusion, in a suitable combination, REO can be applied to improve the quality of meat, but further studies should be conducted to determine the appropriate commercial level for different meat products.

Antimicrobial effects of curcumin against L. monocytogenes, S. aureus, S. typhimurium and E. coli O157:H7 pathogens in minced meat.

The aim of this study was to determine the antimicrobial efficacy of curcumin, one of the active components of the Curcuma longa (turmeric) plant, against food pathogens in a minced meat medium. Salmonella Typhimurium ATCC 14028, Listeria monocytogenes ATCC 7644, Escherichia coli O157:H7 ATCC 33150 and S. aureus ATCC 25923 strains were used as food pathogens. Minimum inhibitory concentrations (MICs) were determined using the macrodilution method. MIC values for curcumin were found to be 125 μg/ml for L. monocytogenes and S. aureus, and 250 μg/ml for S. Typhimurium and E. coli O157:H7. Food pathogens were added to the minced meat at 104 CFU/g (including the control group) and curcumin at doses of 0.5%, 1% and 2% (except the control). The curcumin-supplemented minced meat and control were analysed 0–7 days later. At the end of seven days, it was seen that the 2% dose of curcumin had lowered L. monocytogenes and S. aureus counts by approximately 3 log CFU/g, and E. coli O157:H7 and S. Typhimurium counts by approximately 2 log CFU/g; the 1% dose had lowered L. monocytogenes, S. aureus, E. coli O157:H7 and S. Typhimurium counts by approximately 2 log CFU/g; and that the 0.5% curcumin dose had lowered L. monocytogenes and S. aureus count by approximately 2 log CFU/g, and E. coli O157:H7 and S. Typhimurium count by approximately 1 log CFU/g. Changes in bacterial counts were found to be statistically significant (P ≤ 0.05). It was observed that antibacterial effect increased in direct proportion to dose, while sensory approval decreased. In this study, 0.5% and 1% curcumin doses were determined to be sensorily acceptable. It was concluded that, in view of the scientific benefits and antimicrobial efficacy of curcumin, it may be used instead of, or in smaller doses together with preservative additives in foods where colour change is not important.

Electron microscopy of contractile bands and quality characteristics in high-voltage electrical stimulation broiler breast meat

In this study, 20 broilers were used to examine the effect of high-voltage electrical stimulation (HVES) on meat quality and the microstructure of the pectoralis muscle. After slaughter, carcasses were randomly distributed into 2 treatment groups (n = 10). In the first group, carcasses were electrically stimulated (500 V, 100 Hz) for 60 s. Carcasses in the second group (nonelectrical stimulation) were used as a control. Meat quality was evaluated by the rate of pH, water-holding capacity, cooking loss, color (L*, a*, b*), shear force, and sarcomere length. As a result, HVES increased the rate of muscle pH decline (P < 0.001). High-voltage electrical stimulation had no effect on water-holding capacity and cooking loss values. Only L* (lightness) values were improved during the storage time (P < 0.01). Tenderness (P < 0.001) and sarcomere length (P < 0.05) values were significantly increased at 2 and 5 d postmortem. In addition, microstructure examination demonstrated that the stimulated muscles had longer sarcomeres; however, the A-, I-, and Z-bands and the mitochondrial membrane structure were intact in HVES and nonelectrically stimulated carcasses. The results showed that HVES is a useful method for improving the tenderness of broiler breast meat.