Effects of UV-C irradiation and traditional thermal processing on acemannan contained in Aloe vera gel blends.

The effects of pH (3.5, 4.5, and 5.5) and UV-C irradiation dose (12.8, 24.2, 35.8, and 54.6 mJ/cm2) on the physicochemical properties changes in 10% Aloe vera gel blends; in addition, the acemannan concentration and structural changes in the precipitated polysaccharides were evaluated. A thermal treatment (TT; 45 s at 90 °C) was used for comparison. In contrast to TT, a dose of 24.2 mJ/cm2 did not induce significant changes of free sugar content. Moreover, TT and UV-C irradiation did not significantly affect the content of mannose but increased those of galactose, fructose, and glucose. 1H NMR analysis revealed minimal changes in the isolated fractions of acemannan, indicating that compared to the unprocessed control sample, the acemannan deacetylation was more pronounced by TT (27%) than by UV-C irradiation (11% at 54.6 mJ/cm2), without any significant difference between the two. UV-C irradiation of Aloe vera gel blends at pH 3.5 and 24.2 mJ/cm2 was an alternative to TT and efficiently preserve the characteristics of acemannan.

Physicochemical Changes and Resistant-Starch Content of Extruded Cornstarch with and without Storage at Refrigerator Temperatures.

Effects of extrusion cooking and low-temperature storage on the physicochemical changes and resistant starch (RS) content in cornstarch were evaluated. The cornstarch was conditioned at 20%-40% moisture contents and extruded in the range 90-130 °C and at screw speeds in the range 200-360 rpm. The extrudates were stored at 4 °C for 120 h and then at room temperature. The water absorption, solubility index, RS content, viscoelastic, thermal, and microstructural properties of the extrudates were evaluated before and after storage. The extrusion temperature and moisture content significantly affected the physicochemical properties of the extrudates before and after storage. The RS content increased with increasing moisture content and extrusion temperature, and the viscoelastic and thermal properties showed related behaviors. Microscopic analysis showed that extrusion cooking damaged the native starch structure, producing gelatinization and retrogradation and forming RS. The starch containing 35% moisture and extruded at 120 °C and 320 rpm produced the most RS (1.13 g/100 g) after to storage at low temperature. Although the RS formation was low, the results suggest that extrusion cooking could be advantageous for RS production and application in the food industry since it is a pollution less, continuous process requiring only a short residence time.

Oral fat perception is related with body mass index, preference and consumption of high-fat foods.

Oral sensory perception may play an important role in food preferences, driving food intake and energy balance. Fat perceived in oral cavity has been associated with satiety and homeostatic signals. The purpose of this study was to test the hypothesis that fat oral-intensity perception may be associated with BMI, food preferences and consumption of fat-rich foods. The ability to perceive linoleic acid at different concentrations by intensity scaling was measured in young adults (n=121), characterized by anthropometric measurements such as body mass index (BMI), waist circumference (WC) and total body fat (TBF) percentage. Additionally, dietary habits were recorded online during 35days using a questionnaire designed according to the 24-hour recall and the food diary methods. Finally, food preferences were evaluated online using a nine-point hedonic scale. Taste sensitivity (intensity scaling with suprathreshold concentrations) was estimated with different linoleic acid concentrations using a linear scale of 150mm labeled at the ends. Four groups were established after the ratings for oral-intensity perception of linoleic acid: quartile high ratings (QH), quartile medium-high ratings (QMH), quartile medium-low ratings (QML) and quartile low ratings (QL). Participants with high-intensity ratings for linoleic acid (QH) had lower BMI (p=0.04) and waist circumference (WC) (p=0.03) values than participants in the QL group. High-fat foods (foods with more than 20% of energy from lipids such as fast foods and Mexican street foods) were less preferred by participants with high-intensity ratings for linoleic acid (QH) than by participants with medium- (QMH, QML) and low-(QL) intensity ratings (p<0.01). Also, participants with high-intensity ratings for linoleic acid (QH) presented lower consumption of high-fat foods like fast foods (p=0.04) and Mexican street foods (p=0.03) than subjects with medium- (QMH, QML) and low-(QL) intensity ratings. Overall, these data suggest that the participant's intensity ratings for oral perception of linoleic acid were inversely correlated with BMI, WC, preference and consumption of high-fat foods such as fast foods and Mexican street foods, and it may serve as a predisposing factor for fat consumption in humans.

Effect of ripening, heat processing, and fat type on the micellarization of pigments from jalapeño peppers.

Raw and heat-processed (boiled and grilled) jalapeño peppers at three intermediate ripening stages (brown, 50% red, and 75% red) were digested in vitro without fat and in the presence of soybean oil (SO) or beef tallow (BT), and the micellarization of their lipid soluble pigments (LSP) was measured. The micelles from digestions with brown, 50% red, and 75% red peppers contained up to 27, 35, and 29 different LSP, respectively. Boiling and grilling decreased the micellarization of LSP from brown peppers, whereas the opposite was observed with 75% red peppers. Heat processing did not clearly affect the micellarization of LSP from 50% red fruits. The impact of fat on LSP micellarization was ripening-dependent, but the micellarization of the less polar carotenoids was always increased by SO or BT. This positive effect of fat was higher with SO than with BT.