Neşe Yılmaz

Infrared stabilization of rice bran and its effects on γ‐oryzanol content, tocopherols and fatty acid composition

BACKGROUND Rice bran is a nutritionally valuable by-product of paddy milling. In this study an experimental infrared (IR) stabilization system was developed to prevent rice bran rancidity. The free fatty acid content of raw and IR-stabilized rice bran samples was monitored every 15 days during 6 months of storage. In addition, energy consumption was determined. RESULTS The free fatty acid content of rice bran stabilized at 600 W IR power for 5 min remained below 5% for 165 days. No significant change in γ-oryzanol content or fatty acid composition but a significant decrease in tocopherol content was observed in stabilized rice bran compared with raw bran. IR stabilization was found to be comparable to extrusion with regard to energy consumption. CONCLUSION IR stabilization was effective in preventing hydrolytic rancidity of rice bran. By optimizing the operational parameters of IR stabilization, this by-product has the potential for use in the food industry in various ways as a value-added commodity.

Middle infrared stabilization of individual rice bran milling fractions

The aim of this study was to determine the composition and hydrolytic deterioration behavior of rice bran fractions which were obtained individually from different rice whitening mills. Additionally, stabilization of these bran fractions individually with middle infrared radiation and its effects on the contents of tocopherols and γ-oryzanol were investigated. FFA content of the crude and stabilized bran fractions that were obtained from the last whitening and polishing steps was higher either in the beginning or in the end of the storage compared to the others obtained in the first steps of whitening. Stabilization at 700 W infrared (medium-wave) power for 7.0 min provided 90 days of shelf life without a notable change in FFA content of rice bran fraction which was obtained from the first whitening step. Total tocopherol and γ-oryzanol contents of stabilized rice bran fractions were higher than their crude counterparts.

Time and temperature dependent microbiological and mycotoxin (ochratoxin-A) levels in boza

This study describes the examination of microbiological tests and the determination of OTA in boza temperature and time dependently. Prior to the analysis, physicochemical properties of the boza samples such as moisture, total acidity as lactic acid, pH, protein amount and viscosity were investigated. The incidence of total aerobic bacteria (TAB), lactic acid bacteria (LAB), coliforms, E.coli, Salmonella, S. aureus, B. cereus, yeast and moulds were examined. E.coli, Salmonella, S. aureus and B. cereus were not found in all boza samples. Initially, Aspergillus fumigatus; Acremonium sp.; Geotrichum candidum and Geotrichum capitatum were identified in the samples. Certain extraction techniques such as direct injection, liquid-liquid and solid phase (SP) were tried for the OTA analysis. The most available way was found to be direct injection among them and the recovery was 70.56%+/-9.80 (13.89 RSD). OTA amounts were determined in all boza samples utilizing an isocratic HPLC analysis with an ODS column. OTA was detected in only one sample as 3.58 microg/kg and this amount is above the limits of European Commission Regulations. Time and temperature-dependent changes were investigated and insignificant variation was observed.

Effect of black mulberry (Morus nigra) extract treatment on cognitive impairment and oxidative stress status of d-galactose-induced aging mice

Abstract Context: Morus nigra L. (Moraceae) has various uses in traditional medicine. However, the effect of M. nigra on cognitive impairment has not been investigated yet. Objective: The objective of this study is to determine the phenolic acid content and DNA damage protection potential of M. nigra leaf extract and to investigate the extract effect on cognitive impairment and oxidative stress in aging mice. Materials and methods: Phenolic acid content was determined by quantitative chromatographic analysis. DNA damage protection potential was evaluated on pBR322 plasmid DNA. Thirty-two Balb-C mice were randomly divided into four groups (control, d-galactose, d-galactose + M. nigra 50, and d-galactose + M. nigra 100). Mice were administered d-galactose (100 mg/kg, subcutaneous) and M. nigra (50 or 100 mg/kg, orally) daily for 8 weeks. Behavioral responses were evaluated with Morris water maze. Activities of antioxidant enzymes and levels of malondialdehyde (MDA) were assayed in serum, brain, and liver. Results: In extract, vanillic (632.093 μg/g) and chlorogenic acids (555.0 μg/g) were determined. The extract between 0.02 and 0.05 mg/mL effectively protected all DNA bands against the hazardous effect of UV and H2O2. Morus nigra significantly improved learning dysfunctions (p < 0.01), increased memory retention (p < 0.01), reduced MDA levels (p < 0.05), and elevated SOD, GPx, and CAT activities (p < 0.05) compared with the d-galactose group. Discussion and conclusion: These results show that M. nigra has the potential in improving cognitive deficits in mice and that M. nigra may be useful to suppress aging, partially due to its scavenging activity of free radicals and high antioxidant capacity.

Quality properties, mass transfer characteristics and energy consumption during shortwave infrared radiation drying of tomato

The influence of infrared radiation intensity (1,830, 2,640 and 3,165 W/m2) and air velocity (1.0, 1.5 and 2.0 m/s) on product quality, drying behaviour of tomato and energy consumption were investigated. Five analytical models were used to investigate mass transfer characteristics during infrared drying of tomato slices. The drying time and specific energy consumption varied between 141 and 246 min, and 10.04 and 15.13 MJ/kg water, respectively, and were significantly influenced by infrared radiation intensity and air velocity. Effective moisture diffusivity ranged from 3.89×10-7 to 6.67×10-7 m2/s and was significantly affected by the process variables. Vitamin C content decreased, while lycopene content increased during drying. Total colour change varied between 7.92 and 10.87 for all drying conditions. The logarithmic model gave the best predictions for the drying characteristics of tomato slices for all treatments. Some drying conditions had quite similar results with respect to the operational and qu...