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The texture changes during the initial phase of blanching of potatoes, carrots and green peas at different blanching times (0–240 s) and temperatures (85 °C, 95 °C, 100 °C) were investigated. The breaking force (N) was determined by compression or Back extrusion tests with an Instron texture tester. Electronmicroscopic studies (SEM) were made to support the interpretation of the results.For each vegetable several sections of changes of the breaking force (lnF) were identified. For potatoes a three phase change of the breaking force by all temperatures (85 °C, 95 °C, 100 °C) was observed. In the first of the 3 different observed stages of potato blanching the breaking forces increased with time (0–40 s). In the second and third stage of the blanching process of potato a linear relationship was found between the logarithm of the breaking force and the blanching time. The second phase observed was faster (40–160 s) than the consecutive slower third phase (160–240 s).For green peas the change of the breaking force (lnF) can be described by two consecutive first rate reactions. A faster decreasing period between 0–25 s was followed by a slower decreasing one between 70–140 s. Between the first and second stage of the blanching process there was an initial lag period (25–70 s), which will not be described here. In the period after 140 s, there was not any change, this period is constant.For carrots the fastest change can be observed at 100 °C compared to the results at 85 and 95 °C. A three-phase curve was observed as well. An initial lag period (0–90 s) was followed by a faster (90–190 s) and a slower (190–240 s) decreasing one. In the second and third stage of the blanching process of carrots a linear relationship was found. For the changes of the breaking force (lnF) a kinetical approach was applied, reaction rate constants and apparent activation energies were calculated. The kinetical approach helps to compare and forecast changes at different process conditions.
High hydrostatic pressure (HHP) processing technology offers the possibility to preserve quality attributes. Objective test methods describing quality in a complex form have an important role in the development of new products and in the quality assurance of different technologies. Therefore, research was performed to compare the effects of HHP treatment and heat pasteurization on visual appearance, volatile composition, taste and texture properties of strawberry purees measured by sensorial and objective methods. Sensory evaluation did not show significant differences between samples. Similar result was obtained from the color measurements. Viscosity of purees changed only slightly as a result of the treatments. Electronic nose and electronic tongue were found to be promising tools for discrimination of strawberry purees treated by different levels of high hydrostatic pressure or thermal treatment. Canonical discriminant analysis showed that control and “600 MPa for 5 minutes” samples were quite similar. Samples treated by 600 MPa for 15 minutes were distinguished from the above mentioned ones. The heat treated samples (80°C for 5 and 15 minutes) were definitely separated from the control samples. Fusion of the data from the electronic nose and tongue showed the same trend and improved the classification of the treated puree samples.
Formation and rheological properties of mixed protein-polysaccharide gels (composites) was studied. The composites consisted of whey proteins gelling separately, which were surrounded by polysaccharide gel. The polysaccharide gels were obtained from κ-carrageenan and κ-carrageenan-galactomannan (guar gum and locust bean gum) mixtures. The texture of gels obtained was examined by their compression and bending test. The composite gels obtained from 14% WPI solution and the 1.5% mixture of κ-carrageenan with locust bean gum in a 1:1 ratio exhibited a higher shear stress value at fracture in comparison to WPI gels, but they were less resistant to fracture in the bending test. The texture of gels was highly influenced by pH.
Milk and dairy products are high-value foods; however, consumers suffering from lactose intolerance are not able to enjoy the nutritional benefits of these commodities. There are more and more researches and developments focusing on lowering the lactose content of milk and dairy foods in order to make them available for lactose intolerant people. In this study, we examined the coagulation time, product quality, texture profile properties, and syneresis of yoghurts prepared from lactose-free milk. Significant differences were observed between the control and lactose-free milks with respect to coagulation time and texture profile. The first rupture time, the hardness, and the adhesion force of the lactose-free yoghurt were higher compared to the control product. We observed remarkable difference between the whey leakage of control and lactose free yoghurt samples (21.47% and 14.63%). Results coming from instrumental texture profile analyses showed that the preliminary lactose hydrolysis of milk resulted a firmer texture. It was confirmed by the results of sensory evaluation, and considering the texture and taste, there was significant difference between the control and lactose-free yoghurts.
Sunflower (PSH 569) was used to obtain textured defatted meal. Proximate analysis, water absorption index (WAI), water solubility index (WSI), fat absorption capacities (FAC), foaming capacity (FC), and bulk density (BD) were determined. The objective of the study was the optimization of extrusion conditions for production of textured defatted sunflower meal using response surface methodology (RSM) by evaluating functional properties. It was dried, grinded, and sieved to eliminate hull and fibre. Numerical optimization provided eight solutions with desirability value varying from 0.81 to 0.82. Range of predicted values of FAC (80.96–90.49), WHC (1.95–2.12), WSI (3.22–3.36), WAI (2.84–3.08), bulk density (0.31–0.36), and foaming capacity (14.39–16.30) were used for numerical optimization. Best extrusion conditions were 16.36% feed moisture, 300 r.p.m. screw speed, and 149.40 °C barrel temperature. Textured sunflower defatted meal was prepared using the above optimized conditions.
35 129 131 Tscheuschner, H.-D. (1991) Rheological properties of chocolate masses and cocoa butter dispersions and the texture of chocolate. Food
The aim of the work was to develop a method to evaluate the effect of bread improver dosage on bread crumb texture. Standard breads were prepared to get different crumb structures when bread improver was added to the flour in a concentrate of 0.2%, 0.4% and 0.6%. The additive used in the experiments contains lecithin, ascorbic acid and alpha-amylase. Rheological tests and image analysis were performed to predict the effect of the additive. Hardness, chewiness, gumminess, cohesiveness and springiness were determined by rheological method. The rheological properties neither separately nor combined were able to discriminate the different bread crumb groups. Image processing method was developed to determine the ratio of dark to light area of the images taken of the bread slices. It was concluded that both rheological and visual parameters should be taken into account to characterize bread crumb texture.
Potato wedges were deep, shallow, and par-fried in soybean, sesame, and mustard oils using a laboratory formulated citric acid based antioxidant. The wedges were stored at –18 °C for 10, 20, 30, and 40 days. The quality of the wedges was assessed by subjective method (sensory analysis) and objective method (texture studies). Fuzzy logic was applied as a tool to analyze the linguistic data of subjective evaluation. Objective evaluation was conducted by studies on hardness, shear modulus and shear energy of the wedges. The wedges with highest defuzzified scores (obtained by sensory evaluation) and minimum changes in textural properties (P<0.05) were obtained in par-fried soybean oil (after 40 days storage) and in deep fried sesame and mustard oils (both after 30 days storage). The ranking of fried wedges (in the antioxidant administered oils) based on defuzzified scores after 40 days were: sesame > mustard > soybean (deep fry), mustard > soybean > sesame (shallow fry) and soybean > mustard > sesame (par-fry).
The fat content of Bologna-type turkey sausages was partially replaced with pea fiber or potato starch. Textural properties of full fat turkey sausage were mainly restored in sausages when fat was partially replaced with some levels of pea fiber (0.6, 1.2%) or potato starch (1.9%). Authors observed significant correlation (P<0.01) between instrumentally measured values of hardness and chewiness and sensory ratings of low fat sausages.
The enrichment of bread with wheat bran as a source of dietary fibre seems to be necessary for human health, because bread is the most consumed commodity in many countries. However, wheat bran has some adverse effects on the bread quality during storage. The aim of this study was to produce barbari bread with increased nutritional value and improved texture by the addition of coated wheat bran (0.67 and 1.34% based on flour stearic acid or St1, 2 and beeswax or Bw1, 2). Bread made from uncoated wheat bran was used as control. The least crust to crumb ratio was seen for control and Bw1. Water activity and moisture content results showed that the crumb of Bw1 and control had the better moisture retention during storage. Textural properties of samples showed that there were no significant differences in the hardness of the samples (P>0.05). However, the least increase in hardness during storage was observed for stearic acid coated samples. Other texture profile analysis parameters, such as cohesiveness and springiness, showed that Bw1 and Bw2 samples had no significant changes during storage. Differential scanning calorimetry (DSC) showed the least enthalpy for Bw1 after baking (385.21 J g–1) and during storage (567.62 J g–1). Accordingly, results showed that beeswax, especially at 0.67% (based on flour), is the best shell material for bran coating in order to improve bread texture and shelf life.
