Safa Karaman

Bioactive and Physicochemical Properties of Persimmon as Affected by Drying Methods

In this study, the effects of three different drying methods (freeze drying, oven drying, and vacuum oven drying) on bioactive (total phenolics, total flavonoids, condensed tannin and total hydrolyzable tannin contents, antiradical activity, and antidiabetic activity) and some physicochemical (dry matter, ash, water activity (a w ), color, protein, hydroxymethylfurfural, glucose and fructose content) properties of persimmon fruit were investigated. Simplex lattice mixture design methodology was applied to determine the best solvent mixture for the extraction of phenolics from the samples. It was found that the mixture of acetone:water at the ratio of 50:50 % (v/v) was the best solvent mixture for the extraction. The persimmon powder sample obtained from freeze drying showed significantly (p <0.05) higher bioactivity values than oven- and vacuum-oven-dried samples. Antiradical activity changed significantly depending on the drying method employed and it was superior in freeze-dried samples than that of the other drying methods.

Physicochemical, bioactive, and sensory properties of persimmon-based ice cream: Technique for order preference by similarity to ideal solution to determine optimum concentration

In the present study, persimmon puree was incorporated into the ice cream mix at different concentrations (8, 16, 24, 32, and 40%) and some physicochemical (dry matter, ash, protein, pH, sugar, fat, mineral, color, and viscosity), textural (hardness, stickiness, and work of penetration), bioactive (antiradical activity and total phenolic content), and sensory properties of samples were investigated. The technique for order preference by similarity to ideal solution approach was used for the determination of optimum persimmon puree concentration based on the sensory and bioactive characteristics of final products. Increase in persimmon puree resulted in a decrease in the dry matter, ash, fat, protein contents, and viscosity of ice cream mix. Glucose, fructose, sucrose, and lactose were determined to be major sugars in the ice cream samples including persimmon and increase in persimmon puree concentration increased the fructose and glucose content. Better melting properties and textural characteristics were observed for the samples with the addition of persimmon. Magnesium, K, and Ca were determined to be major minerals in the samples and only K concentration increased with the increase in persimmon content. Bioactive properties of ice cream samples improved and, in general, acetone-water extracts showed higher bioactivity compared with ones obtained using methanol-water extracts. The technique for order preference by similarity to ideal solution approach showed that the most preferred sample was the ice cream containing 24% persimmon puree.

Recovery potential of cold press byproducts obtained from the edible oil industry: physicochemical, bioactive, and antimicrobial properties.

Physicochemical, bioactive, and antimicrobial properties of different cold press edible oil byproducts (almond (AOB), walnut (WOB), pomegranate (POB), and grape (GOB)) were investigated. Oil, protein, and crude fiber content of the byproducts were found between 4.82 and 12.57%, between 9.38 and 49.05%, and between 5.87 and 45.83%, respectively. GOB had very high crude fiber content; therefore, it may have potential for use as a new dietary fiber source in the food industry. As GOB, POB, and WOB oils were rich in polyunsaturated fatty acids, AOB was rich in monounsaturated fatty acids. Oil byproducts were also found to be rich in dietary mineral contents, especially potassium, calcium, phosphorus, and magnesium. WOB had highest total phenolic (802 ppm), flavonoid (216 ppm), and total hydrolyzed tannin (2185 ppm) contents among the other byproducts. Volatile compounds of all the byproducts are mainly composed of terpenes in concentration of approximately 95%. Limonene was the dominant volatile compound in all of the byproducts. Almond and pomegranate byproduct extracts showed antibacterial activity depending on their concentration, whereas those of walnut and grape byproducts showed no antibacterial activity against any pathogenic bacteria tested. According to the results of the present study, walnut, almond, pomegranate, and grape seed oil byproducts possess valuable properties that can be taken into consideration for improvement of nutritional and functional properties of many food products.

Comparison of adaptive neuro-fuzzy inference system and artificial neural networks for estimation of oxidation parameters of sunflower oil added with some natural byproduct extracts

BACKGROUND Apple pomace, orange peel and potato peel, which have important antioxidative compounds in their structures, are byproducts obtained from fruit or vegetable processing. Use of vegetable extracts is popular and a common technique in the preservation of vegetable oils. Utilization of apple pomace, orange peel and potato peel extracts as natural antioxidant agents in refined sunflower oil during storage in order to reduce or retard oxidation was investigated. All byproduct extracts were added at 3000 ppm to sunflower oil and different nonlinear models were constructed for the estimation of oxidation parameters. RESULTS Peroxide values of sunflower oil samples containing different natural extracts were found to be lower compared to control sample. Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural networks (ANN) were used for the construction of models that could predict the oxidation parameters and were compared to multiple linear regression (MLR) for the determination of the best model with high accuracy. It was shown that the ANFIS model with high coefficient of determination (R(2) = 0.999) performed better compared to ANN (R(2) = 0.899) and MLR (R(2) = 0.636) for the prediction of oxidation parameters CONCLUSION Incorporation of different natural byproduct extracts into sunflower oil provided an important retardation in oxidation during storage. Effective predictive models were constructed for the estimation of oxidation parameters using ANFIS and ANN modeling techniques. These models can be used to predict oxidative parameter values.

Enrichment of wheat chips with omega-3 fatty acid by flaxseed addition: textural and some physicochemical properties.

In the present study, wheat chips enriched with flaxseed flour were produced and response surface methodology was used for the studying the simultaneous effects of flaxseed level (10-20%), frying temperature (160-180 °C) and frying time (40-60 s) on some physicochemical, textural and sensorial properties and fatty acid composition of wheat chips. Ridge analysis was conducted to determine the optimum levels of processing variables. Predictive regression equations with adequate coefficients of determination (R² ≥ 0.705) to explain the effect of processing variables were constructed. Addition of flaxseed flour increased the dry matter and protein content of samples and increase of frying temperature decreased the hardness values of wheat chips samples. Increment in flaxseed level provided an increase in unsaturated fatty acid content namely omega-3 fatty acids of wheat chips samples. Overall acceptability of chips increased with the increase of frying temperature. Ridge analysis showed that maximum taste score would be at flaxseed level = 10%, frying temperature = 180 °C and frying time = 50 s.

Barley flour addition decreases the oil uptake of wheat chips during frying

In the present study, wheat chips enriched with barley flour at different concentrations (5, 10, 15, 20, 25 and 30%) were produced and some physicochemical and textural properties, fatty acid composition and sensory quality of enriched chips were investigated. An increase in the values of some physicochemical parameters of wheat chips, namely hardness, dry matter, ash and some fatty acids levels, was observed with the increasing barley flour concentration in the formulation. Barley flour addition provided a significant oil uptake reduction as the oil content of the control sample was 27.23% while that of the enriched samples with 30% barley flour was 18.21%. Overall acceptability of wheat chips added with no barley flour samples was determined to be similar to compared to enriched ones. But addition of barley flour higher than 10% caused a decrease in sensory scores of the final products.

Exposure to Air Accelerates the Gelation of Gelatin: Steady and Dynamic Shear Rheological Characterization to See the Effect of Air on the Strength of Gelatin Gel

In the current study, the effect of air exposure to the gelatin solution on improvement of gel structure was investigated in terms of the steady and dynamic shear rheological properties. Prepared gelation solution (5% w/v) was covered to prevent air incorporation and it was subjected to 5 h gelatin and rheological analyses were carried out for the comparison of non-covered ones. It was observed that the preventing of air into the gelatin solution affected the rheological parameters. Apparent viscosity and complex viscosity values of samples increased during gelation and these values were measured to be tremendously high (1.894 and 8.346 Pa s, respectively) in non-covered gelatin solution while they were 0.474 and 1.611 Pa s in covered samples after 5 h gelation, respectively. Similarly, storage modulus (G′) of samples increased with the increase in gelation time and it was recorded to be 52.203 Pa in gelatin solution exposed to air while it was 9.848 Pa in gelatin solution covered to prevent air incorporation. These results showed importance of air in gelatin solution to the food industry using gelatin in food formulation for the structure of processed foods.

Steady, dynamic, creep/recovery, and textural properties of yoghurt/molasses blends: Temperature sweep tests and applicability of Cox–Merz rule

In this study, physicochemical, rheological (steady, dynamic, and creep/recovery), and textural properties of yoghurt/molasses blends (0, 5, 10, and 15% molasses) were investigated. The blends showed shear thinning behavior, as described by Ostwald de Waele model (R2 ≥ 0.955). Consistency coefficient value (K) of the blends decreased with increasing molasses concentration in the sample. Storage modulus (G′) of blends was higher than loss modulus (G″), exhibiting weak gel-like behavior. Molasses addition decreased G′ and G″ values. Temperature sweep tests indicated that blends followed Arrhenius relationship. A modified Cox–Merz rule was applicable using shift factors. Compliance values (J(t)) increased as molasses concentration increased, revealing that deformation stability and internal viscosity (η1) decreased with concentration. Creep behavior was characterized using Burger model. Obtained J data as a function of time could be satisfactorily fitted to Burger model (R2 ≥ 0.994). The final percentage recovery of blends remarkably decreased with the increase of molasses concentration. Firmness, consistency, cohesiveness, and viscosity index values decreased with molasses addition. According to the results of the current study, molasses amount to be added to the yoghurt should be determined regarding rheological properties since resistance of the sample to deformation decreased with increase in molasses concentration.

Rheological and some Physicochemical Properties of Selected Hydrocolloids and their Interactions with Guar Gum: Characterization using Principal Component Analysis and Viscous Synergism Index

In this study, rheological and some physicochemical characteristics of some commercial hydrocolloids were determined. Principal component analysis and viscous synergism index (Iv) were used for the characterization of gums. Specific gravity and pH values of hydrocolloids were in the range of 0.431–1.010 and 5.470–9.830, respectively. Power law model was used to describe the viscous flow behavior of hydrocolloids. In general, hydrocolloids exhibited significant differences in many physicochemical characteristics (p < 0.05). When used individually, xanthan gum showed the highest K (5.131 Pa sn) compared to others. The highest K value was calculated to be 11.570 Pa sn for xanthan and guar gum mixture, which shows a synergistic interaction (Iv = 0.866), while the lowest was for tara and guar gum mixture (0.212 Pa sn), which shows an antagonistic interaction (Iv = 0.459). The n values were in the range of 0.118–0.816 and 0.098–0.619 for sole and mixture hydrocolloids, respectively. Nine physiochemical and rheological variables were reduced to two independent principal components, which accounted for 88.42% of the total variance. Moisture, pH, water holding capacity, oil holding capacity, and ash resulted in the most effective variables for the PC1 while specific gravity, consistency coefficient, and flow behavior index were useful to define the PC2.

Dynamic Mechanical Spectra of Selected Turkish Honeys: Construction of Predictive Models for Complex Viscosity Using Two Different Nonlinear Modeling Techniques

Dynamic oscillatory shear rheological characteristics of honey samples from different floral sources were evaluated using frequency sweep test and stress sweep test at three different temperatures (10, 15, and 20°C). All honey samples showed liquid-like behavior because the loss modulus was significantly greater than the elastic modulus. Pine honey showed the highest complex viscosity (86.33 Pa s at 10°C), while the lowest complex viscosity was observed in citrus honey (22.15 Pa s) at the same temperature. Temperature dependency of complex viscosity of honey samples was modeled by Arrhenius model and activation energy values of honeys ranged from 83.13 to 97.46 kJ/mol. An efficient predictive model for complex viscosity values of honeys was constructed using adaptive neuro fuzzy inference system that showed satisfactory prediction performance with high coefficient of determination (0.995) and low root mean square error (0.04) in the validation period compared to artificial neural networks.