Muharrem Certel

Moisture adsorption isotherms of Tarhana at 25 °C and 35 °C and the investigation of fitness of various isotherm equations to moisture sorption data of Tarhana

Moisture adsorption isotherms of Tarhana were determined at 25 °C and 35 °C. As the temperature increased, the adsorbed moisture content decreased at water activities between 0.2 and 0.9. The experimental sorption data obtained were applied to the Halsey, Harkins-Jura, Smith, BET and Freundlich isotherm equations to test fitness of these equations to Tarhana. The order of best fit or sorption data obtained for Tarhana was Halsey > Harkins-Jura > Smith > Henderson > BET > Freundlich. The obtained sorption data fitted the Halsey, Harkins-Jura and Smith isotherm equations quite well in the 0.2–0.9 water activity range; However, the best fit was obtained in the Freundlich, BET and Henderson isotherm equations in this water activity range. © 2000 Society of Chemical Industry

The effect of fermentation and storage on free amino acids of tarhana.

A study on the evaluation of free amino acids (FAAs) in tarhana during fermentation and storage was performed. The FAAs in tarhana were determined by RP-HPLC with a fluorescence detector following extraction from the sample and derivatization with dansyl chloride. The amount of FAAs increased significantly (p<0.01) during fermentation and storage. The increase in the content of total free amino acids (TFAAs) and total free essential amino acids (TFEAAs) of fermented tarhana, which was used with yogurt bacteria and bakers yeast, was 57% and 93%, respectively. The amino acids primarily responsible for the increase were valine and tryptophan followed by methionine, alanine, isoleucine + leucine, phenylalanine, arginine, proline, and lysine. The TFAA content of tarhana at the end of fermentation was found to be 8% of total protein (16.8%). The ratio of TFEAAs/TFAAs was initially 0.46 and increased to 0.57 at the end of fermentation. The TFAA content of wet tarhanas was higher than that of the dry counterpart. It was found that the TFAA content of dry tarhana was 25% lower than the fresh wet tarhana (FWT), at the end of fermentation. It was concluded that the decrease in FAAs in dry tarhana was due to the Maillard reaction and partial degradation of FAAs during dehydration.

Quality characteristics of gluten-free cookies made of buckwheat, corn, and rice flour with/without transglutaminase

Buckwheat is one of the most valuable pseudo-cereals in terms of its nutritional composition, and it is suitable for celiac patients because of its gluten-free characteristic. However, gluten is the main structure-forming protein responsible for the development of structure in baked products. Therefore, it is a challenge to produce high-quality gluten-free products. Transglutaminase addition is a relatively common application used in the production of gluten-free baked goods. The objective of this study was to investigate the combination of buckwheat flour with rice and corn flour at different levels in gluten-free cookie formulations and the impact of transglutaminase on the quality of cookies. Quality parameters evaluated were proximal chemical composition, spread ratio, color, and textural parameters (hardness and fracturability). Spread ratio, protein, crude fiber, ash content, and also b* and hardness values were significantly (p < 0.05) affected by flour combinations. Further, addition of transglutaminase resulted in increased moisture content, spread ratio, and fracturability but decreased hardness values.

Kinetic and thermodynamic investigation of mancozeb degradation in tomato homogenate during thermal processing.

BACKGROUND The kinetic and thermodynamic parameters of mancozeb degradation in tomato homogenates under the conditions prevailing in the manufacture of tomato products (at 60-100 °C for 0-60 min) were investigated. A gas chromatography-mass spectrometry method was used to analyse residual mancozeb in tomato homogenate. Ethylenethiourea (ETU), the main toxic degradation product of mancozeb, was measured by high-performance liquid chromatography (HPLC)-with photodiode array detector (PDA). RESULTS The degradation of mancozeb and the formation of ETU in tomato homogenates were adequately described as first-order kinetics. Dependence of the rate constant followed the Arrhenius relationship. Apparent activation energies, temperature coefficients, half time and time to reduce to 90% of the initial value of mancozeb were calculated as kinetic parameters. The thermodynamic parameters of mancozeb were also described as Δg(d) = - 2.440 and 7.074 kJ mol⁻¹; Δh(d) = - 32.555 and - 42.767 kJ mol⁻¹; Δs(d) = - 0.090 and - 0.150 kJ mol⁻¹ K⁻¹; K(e) = 0.414 and 9.797 L g⁻¹ for 333 and 373 K respectively. CONCLUSION Current findings may shed light on the reduction of mancozeb residue and its toxic degradation product during thermal processing of tomatoes and may also be valuable in awareness and prevention of potential risks from dietary exposure.

Functional Characteristics of Egg White Proteins within Wheat, Rye, and Germinated-Rye Sourdoughs

Egg white (EW) proteins are functional proteins, which possess certain biological activities (antimicrobial, antigenic, and peptidase-inhibitory) that may influence the food processing or vice versa can be affected by processing. This study investigated the behavior of EW proteins within sourdough systems with respect to proteolysis and fermentation parameters, and the ability of EW to build foam structures with sourdoughs. Of the EW proteins, ovotransferrin was hydrolyzed in all sourdoughs (wheat, rye, and germinated-rye), whereas the breakdown of ovalbumin was specific for germinated-rye sourdoughs, with the cysteine endopeptidases being responsible for the hydrolysis. The presence of EW in sourdough fermentations had no influence on the prolamin hydrolysis or the growth of starter culture, indicating that the peptidase-inhibitory and antimicrobial properties of EW play no important role in sourdoughs. EW foams, however, appeared as potential structure builders in sourdough applications and could serve as alternative structural agents in the production of baked goods with low gluten content.

Development of an analysis method for determination of sulfonamides and their five acetylated metabolites in baby foods by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap-MS)

A high sensitive and reliable multiresidue method was developed and validated for determination of twelve sulfonamides and five acetylated metabolites in baby foods by using UHPLC-Orbitrap-MS. The sample preparation included two extraction methods as QuEChERS and ASE. The original QuEChERS method was performed, whereas ASE method was optimized to achieve the best recovery for all analytes. UHPLC-Orbitrap-MS parameters were optimized to obtain good retention and separation in LC and high sensitivity and selectivity in MS. The performance of the method was evaluated according to the European Commision Decision 2002/657/EC. Matrix matched calibration curves showed good r2 (≥0.999) and LOQ was ranged from 0.10 to 0.55μg/kg. ASE was significantly more effective for extraction of the analytes (recovery ranged from 75.5 to 96.6% with RSD≤10.1%) than QuEChERS (recovery ranged from 60.9 to 85.9% with RSD≤19.1%). This method was applied to the analysis of 47 different baby foods and no positive samples were found.

OPTIMISATION OF Bacillus amyloliquefaciens FE-K1 EXTRACELLULAR PEPTIDASE PRODUCTION BY RESPONSE SURFACE METHODOLOGY

Bu calismada, daha once sunmus ekmekten izole edilmis olan Bacillus amyloliquefaciens FE-K1’in ekstraseluler peptidaz uretiminin, merkezi kompozit tasarima (MKT) dayali yanit yuzey yontemi (YYY) ile optimize edilmesi amaclanmistir. Yanit yuzey yonteminde sicaklik (20-45°C), enzim uretim ortaminin baslangic pH degeri (pH 5-9) ve inokulasyon seviyesi (%1-5, v/v) faktor olarak kullanilmis, fermentasyon suresi her deneme icin ayri ayri belirlenmistir. Sonuclar optimum peptidaz uretiminin 33,4°C, pH 6,62 ve %2,3 inokulasyon seviyesinde elde edildigini gostermistir. Optimum kosullar altinda fermentasyon suresinin sadece 7 saat, ham enzimin aktivitesinin 49,17U/mL, spesifik aktivitesinin ise 504,77U/mg oldugu tespit edilmistir.

Determination of peptidase production potential of Bacillus strains isolated from ropey bread and optimisation of some culture conditions for peptidase production

Bu calismada daha onceki bir calismada sunmus ekmeklerden izole edilen 14 adet Bacillus susunun, 30 °C, 37 °C, 50 °C ve 55 °C’de peptidaz uretme potansiyellerinin belirlenmesinin ardindan, peptidaz aktivitesi en yuksek olan iki sus icin en uygun enzim uretim besiyeri bilesimi ve kosullarinin bir kerede bir faktor yaklasimi ile optimizasyonu yapilmistir. Bu amacla en iyi aktivite degerini saglayan karbon ve azot kaynagi ile karbon/azot orani, calkalama hizi ve on kultur besiyeri secimi maliyet unsuru da goz onunde bulundurularak tespit edilmistir. En iyi karbon ve azot kaynaginin sirasiyla glukoz ve maya ekstrakti oldugu saptanmistir. Ayrica karbon/azot oraninin 1:5, calkalama hizinin 250 rpm olmasi durumunda ve on kultur hazirlanmasi icin enzim uretim ortami ile ayni besiyeri kullanildiginda daha yuksek peptidaz aktivitesi degeri elde edilmistir.

Effects of Extraction Rates of Wheat Flour on Phyllo (Yufka) Properties at Different Storage Temperatures

ABSTRACT Phyllo sheets were produced with flour obtained at different extraction rates (53, 58, or 67%), and stored at 4 and 25°C. Physical, chemical, and sensory properties of fresh and stored phyllo were researched. Fresh phyllo samples from wheat flour at 53% extraction rate were thinner (0.4 mm) and had whiter color (L* = 87.6). Textural properties and overall sensory acceptability of phyllo samples significantly decreased (P ≤ 0.01) with increased extraction rates and storage times. At the end of four days, toughness and extensibility decreased from 0.88 N and 10.9 mm to 0.65 N and 6.7 mm at 4°C and to 0.45 N and 5.6 mm at 25°C. The 53% extraction rate was more suitable for producing phyllo. The shelf life of phyllo samples for preparing borek was determined four days at 4°C and two days at 25°C according to acid contents and sensory properties.