Gulum Sumnu

Microwave Assisted Extraction of Phenolic Compounds from Sour Cherry Pomace

Microwave assisted extraction of sour cherry pomace at different conditions were compared with conventional extraction in terms of total phenolic content and antiradical efficiency. Total phenolic content and antiradical efficiency at the optimum conditions (700 W, ethanol-water, 12 min, 20 mL solvent/ g solid) of microwave assisted extraction were 14.14 mg GAE/g sample and 28.32 mg DPPH·/g sample, respectively. Total phenolic content and antiradical efficiency of extracts obtained by conventional extraction were 13.78 mg GAE/g sample and 24.74 mg DPPH·/g sample, respectively. Microwave assisted extraction increased antiradical efficiency and concentration of phenolic acids and shortened extraction time significantly.

Quality of Gluten-Free Bread Formulations Baked in Different Ovens

The objective of this study was to determine the effects of different tigernut flour/rice flour ratios (0:100, 5:95, 10:90, 15:85, 20:80, and 25:75) on quality of gluten-free bread formulations baked in infrared–microwave combination and conventional ovens. The degrees of the starch gelatinization of breads baked in different ovens were also compared. Conventionally baked breads prepared with tigernut flour/rice flour ratio of 10:90 and the infrared–microwave combination-baked breads prepared with tigernut/rice flour ratio of 20:80 had the most acceptable firmness and specific volume values. These breads had also similar color. Tigernut flour had significantly higher gelatinization temperatures and lower gelatinization enthalpy (ΔHg) values than rice flour (p ≤ 0.05). As rice flour was replaced with tigernut flour, lower ΔHg values were observed in dough samples. Breads baked in both conventional and combination oven had sufficient starch gelatinization degrees ranging from 91% to 94% and from 84% to 85%, respectively.

Color and Texture Development During Microwave and Conventional Baking of Breads

Abstract The color parameters (L*, a*, and b*) and hardness of breads baked in microwave and conventional ovens were compared. Moreover, the effect of susceptor on color and texture development during microwave baking were studied. Microwave oven was operated at 30 and 40% powers for 3.5–5.5 min with half-minute intervals. Breads were baked in conventional oven at 175°C and 200°C for 10–18 min and at 225°C for 4–12 min with 2 min intervals. It was not possible to obtain sufficient brown color on the surfaces of the breads in microwave baking. Usage of susceptor helped the achievement of brown color on bottom surfaces of breads. Zero order kinetic model was proposed for L* variation of breads during microwave and conventional baking. Hardness of microwave and conventionally baked breads increased during baking. Rates of hardness variation in microwave baked breads were higher than that in conventionally baked breads.

Recent Developments in Microwave Heating

Publisher Summary Microwaves directly interact with food and heat is generated volumetrically. In addition to concentration gradients, pressure gradients play an important role in moisture transfer during microwave heating. Short processing time in microwave drying, sterilization, and thawing is advantageous to reduce quality, losses especially for perishable food products. However, some quality problems are observed in microwave-baked products because of insufficient time for some biochemical reactions to occur. Development of new formulations or the use of halogen lamps in combination with microwaves has been shown to improve the quality of baked products. Product quality and heating uniformity in various microwave processes can be improved by changing the oven design such as phase control heating, variable frequency ovens, cycling microwave power method, using continuous microwave power at lower levels or combining microwaves with other heating methods. New methods, such as magnetic resonance thermal imaging, intrinsically produced compounds (chemical markers), and time temperature indicator methods, which are used for the determination of temperature distribution within the food material, will be helpful for widespread usage of microwave pasteurization and sterilization systems.

Extraction of Essential Oil from Laurel Leaves by Using Microwaves

Abstract The effects of microwave power and time in solvent-free microwave extraction (SFME) on the yield and composition of the essential oil obtained from laurel (Laurus nobilis L.) leaves were studied. The extraction was also performed by hydrodistillation as a control. Specific gravities and refractive indices of the essential oils obtained by different methods and at various conditions were also examined. The main constituent of laurel essential oil was 1,8-cineole (630–730 mg/mL). Essential oils obtained by SFME and hydrodistillation were comparable with respect to both yield and composition while the process time was reduced by 55–60% when SFME was used.

EFFECTS OF HYDROCOLLOIDS ON APPARENT VISCOSITY OF BATTERS AND QUALITY OF CHICKEN NUGGETS

ABSTRACT The effect of different types of starches and gums on batter consistency and the effect of batter consistency on quality parameters of deep-fat fried chicken nuggets were determined in this study. Consistency of batter was correlated with coating pickup and oil content of the product. Addition of different starch and gum species to batter was found to be effective for both viscosity development and quality attributes of deep-fat fried chicken nuggets. Hydroxypropyl methylcellulose gum (HPMC), xanthan gum, and pregelatinized starch provided the highest consistency to the batters. Amylomaize starch addition to the batter formulation provided about 50% increase in texture of nuggets as compared to the control. Chicken nuggets coated with batters containing HPMC, xanthan, or guar gum had the lowest oil content. HPMC reduced oil content by about 54%, while the reduction in oil content was 40% and 33% in the case of xanthan and guar gum addition, respectively.

Temperature and weight loss profiles of model cakes baked in the microwave oven.

Model cake systems were formulated with wheat and rice starches at hydration levels of 112.5% and 137.5% (flour weight basis) and baked in a microwave oven at power levels of 80% and 100%. Temperature profiles and weight loss profiles of the cakes baked in the microwave oven were compared with those of the cakes baked conventionally. One cake was baked at a time, and three replications of each treatment were used. Center and edge temperatures of microwave cakes increased significantly with increasing moisture content of the batter and oven power. Weight loss of the cakes was dependent on oven power, starch type and hydration levels. Cakes baked in the microwave oven had greater weight loss than the cakes baked in convection mode. Wheat starch cakes had greater volumes than rice starch cakes. Rice starch cakes were more tender than wheat starch cakes.

EFFECTS OF MICROWAVE COOKING ON FISH QUALITY

Changes in tenderness, unit proteolytic activity, protein denaturation and fatty acid content of trout (Onchorhyncus mykiss) cooked in microwave oven for different time-power combinations were studied and the relationship between protein denaturation and textural changes was investigated. Trout was cooked in the microwave oven at 20, 40 and 60% powers for 10, 20, 30, 40 s. As a control uncooked fish was used. Proteolysis was controlled by using microwave energy. Texture degradation due to proteolytic enzymes was reduced as microwave power increased. As cooking time and/or power of the microwave oven increased, proteolytic activity decreased which was a sign of the increase in enzyme inactivation. A correlation was found between the variation of texture and proteolytic activity (r = 0.973). It was observed that proteolytic enzymes were effective especially on myosin. Most of the fatty acids were not destroyed during microwave cooking. The optimum cooking conditions in microwave oven were determined as 60% power for 20 s of cooking time.

The effect of different formulations on physical properties of cakes baked with microwave and near infrared-microwave combinations.

The aim of this study was to determine the effect of different formulations on color and textural characteristics of different cakes during baking in microwave and near infrared-microwave combination ovens. For comparison, cakes were also baked in conventional ovens. Color and hardness for both types of baking schemes were found to be dependent on formulation. Cakes containing Simplesse™ a fat replacer consisting mostly of whey protein, baked in microwave and near infrared-microwave combination ovens were found to be the firmest cakes.

Effects of susceptor, coating and conventional browning applications on color and crust formation during microwave baking

The effects of different browning treatments on the crust color and crust hardness of microwave baked breads were investigated. Microwave oven was operated at 20%, 30% and 40% powers for 3.5–5.5 minutes. As a control, breads were baked in a conventional oven at 200°C for 12 minutes. After microwave baking, breads were browned or conventional browning times increased, crust hardness and weight loss of breads increased. When susceptors were used, desired browning and hardness were obtained on the bottom surfaces of the breads. However, they did not affect top surface color significantly. The optimum microwave baking conditions for safety susceptor and standard susceptor were found as 5.0 minutes at 20% power and 4.5 minutes at 20% power, respectively. Breads coated with a solution composed of 10.5% sodium bicarbonate, 31.6% glucose, 5.3% glycine and 52.6% water (by weight) did not have the desired crust color and hardness. Conventional browning at 200°C for 8 minutes was an alternative to achieve browning on top and bottom surfaces and crust formation on the bottom surface.