Talip Kahyaoglu

Characterization of a new biodegradable edible film made from salep glucomannan.

The aims of this study were to report the film-forming properties of salep glucomannan (SG) and characterize its physical, barrier, mechanical, sorption and thermal properties for the first time. Galactomannan films (LBG, locust bean gum; GG, guar gum) were also prepared to compare with SG films. The steady and oscillatory rheological behaviors of the film solution were evaluated. The viscosity of the SG was less dependent than that of LBG and GG on temperature. The physical properties of SG films showed good potential for food applications. The oxygen and water vapor barrier properties of SG were better than LBG and GG films. SG film was less mechanically resistant than LBG but more flexible than galactomannan films. The highest transition temperature (Tg) was determined to be -11.46 ± 0.65°C for SG film. The results showed that SG has good potential for use in producing an edible film for various food applications.

The effect of gum tragacanth on the rheological properties of salep based ice cream mix

The influence of concentration (0-0.5%, w/w) of gum tragacanth (GT) on thixotropy, dynamic, and creep-recovery rheological properties of ice cream mixes prepared with milk or water based were investigated. These properties were used to evaluate the viscoelastic behavior and internal structure of ice cream network. The textural properties of ice cream were also evaluated. Thixotropy values of samples were reduced by increasing GT concentration. The dynamic and creep-recovery analyses exhibited that GT addition increased both ice cream elastic and viscous behaviors. The increasing of Burgers model parameters with GT concentration indicated higher resistance network to the stress and more elastic behavior of samples. The applying of Cox-Merz rule is possible by using shift factor (α). GT also led to an increase in Youngs modulus and the stickiness of ice creams. The obtained results highlighted the possible application of GT as a valuable member to promote structural properties of ice cream.

Manufacture and characterization of kefir made from cow and buffalo milk, using kefir grain and starter culture.

The microbiological and chemical characteristics as well as organic and amino acid profiles of kefir samples made from cow and buffalo milks fermented by kefir grains and starter culture were investigated during storage for 21 d at 4°C. After incubation, lactic, acetic, and citric acid concentrations showed a difference among the samples due to milk type and production methods. Storage time had little effect on the organic acid values of kefir samples. As compared with cow milk kefir, buffalo milk kefir had higher numbers of microorganisms, except lactobacilli, at the end of storage. Whereas pH and titratable acidity exhibited similar changes during storage in all kefir samples, ethanol levels were significantly increased in buffalo milk kefir samples. Glutamic acid was the major amino acid at all sampling times for all samples. Tyrosine, serine, histidine, alanine, methionine, and lysine concentrations were determined to be different in all samples depending on milk type. In general, due to the higher microbial population (especially yeast), kefir made from buffalo milk may be preferred.

Natamycin content and quality evaluation of yoghurt from small- and large-scale brands in Turkey.

In this study, the presence of natamycin and quality parameters of yoghurt samples manufactured by small- and large-scale dairy firms in Turkey were investigated. Physicochemical and microbiological results revealed that, except Lactobacillus bulgaricus and Streptococcus thermophilus counts, the majority of the yoghurts manufactured by small-scale dairy firms were found to be out of the limits. Natamycin was detected in 31 and 2 yoghurt samples from small- and large-scale brands, respectively. The levels of natamycin in small-scale brand yoghurts were higher than those in large-scale brand yoghurts. Of the analysed samples, 42.3% did not comply with the Turkish Food Codex.

Influence of an ultrasonic nozzle in spray‐drying and storage on the properties of blueberry powder and microcapsules

BACKGROUND Recently, ultrasonic nozzle technology has been applied in spray-drying because of its numerous advantages, including providing more uniform droplets and reducing damage observed in bioactive compounds. In this study, the production of blueberry powders and microcapsules by using an ultrasonic spray nozzle was investigated. Firstly, the important ultrasonic nozzle parameters were optimised by using response surface methodology and compared with a conventional nozzle (control). Secondly, powder and microcapsules obtained at the optimum point were stored at 22 °C and 35 °C at 0.32 water activity (aw ). RESULTS The optimum conditions were estimated as 125 °C inlet air temperature, 9 W ultrasonic power and 8% feed pump rate. There was significantly difference (P < 0.05) in the total phenolic content and antioxidant power of microcapsules produced by an ultrasonic nozzle and a conventional nozzle. Because the temperature affected the stability of powders negatively, the blueberry powder showed higher losses than microcapsules in the content of bioactive compounds. In addition, the ultrasonic nozzle showed a significantly greater protective effect on physico-chemical properties than did the conventional nozzle. CONCLUSION Results of the study point that the production of ultrasonic nozzle powders and microcapsules is feasible to use as a functional ingredient in food industry.

Purification of glucomannan from salep: Part 1. Detailed rheological characteristics

The aim of this study was to investigate the effects of different extraction temperatures (25, 55 and 85°C) on the rheological characteristics of glucomannan (GM) purified from salep. GM was isolated using the following method: extraction of GM with water, removal of impurities by centrifugation and precipitation of GM with ethanol. The extraction yield of GM was approximately 45% for all products. Higher GM (95%) and lower starch (3%) contents were obtained for GM25. GM25 showed higher apparent and intrinsic viscosity, storage and loss modulus and lower activation energy than GM55 and GM85. The addition of different salts and sugars did not affect viscosity due to the non-polyelectrolyte behavior of GM. Gel behavior of purified samples appeared at pH 9. The usage of salep in milk was reduced by purification. These results are potentially useful for widening the applications for salep and for furthering research and development of GM.

Purification of glucomannan from salep: Part 2. Structural characterization

The aim of this study was to investigate the effects of different extraction temperatures (25, 55 and 85°C) on the structural characteristics of glucomannan (GM) purified from salep. All extraction conditions reduced protein content and molecular weight of salep. The effectiveness of removing the impurities and the highest purity of GM25 were observed with size exclusion profile. FTIR experiments demonstrated the presence of acetyl group, reduction of protein content and increment of polymer interaction of GM25. XRD patterns of GM25 with narrower and higher intensity than GM55, GM85 and native salep indicated strengthened interaction of GM25. Higher particle size was determined for GM25. The degradation peak observed with DSC increased from 293 to 314°C and GM25 had the higher thermal stability which was also supported with TGA results. These results could provide widening the applications in food industry and other fields and also progressing development of salep with a better structural characteristic.

Improving Rheological and Baking Properties of Gluten-Free Breads Using Defatted Hazelnut Flour with Various Gums

Abstract Defatted hazelnut flour (DHF) in different levels (5 %, 10 % and 15 %) of locust bean, guar and xanthan gum were added in rice-based gluten-free formulations to improve rheological properties of dough and baking properties of bread. The rheological characteristics of dough samples were determined by steady flow curves and dynamic tests. The baking properties of breads were evaluated by specific volume, Textural Profile Analysis (TPA) parameters and color values. The rheological measurements showed that all gluten-free dough had pseudoplastic behavior. Specific volume values of breads ranged from 2.20 to 2.83 cm3/g. Gum addition enhanced the specific volume of gluten-free breads. Hardness values of gluten-free breads ranged from 1,069.80 to 3,135.88 g and DHF addition of gluten-free formulations caused significant decrease of the hardness values of breads (p < 0.05). DHF addition in gluten-free formulations made bread crumb darker than bread without DHF and gum. DHF addition also increased a and b values of gluten-free bread’s crumb.