Effects of cooking, drying and pretreatment methods on texture and starch digestibility of instant rice

Instant rice produced from a conventional process consisting of the cooking, washing and drying steps possesses poorer eating quality compared with that of freshly cooked rice. The objective of this work was therefore to study the effects of cooking, pretreatment and drying methods on microstructure, textural properties and starch digestability of instant rice after rehydration; jasmine white rice was chosen as a test material. Conventional boiling method and electric rice cooking were selected as the methods to prepare cooked rice. In the case of boiling, cooked rice was frozen at −20 °C or cooled at 4 °C for 24 h prior to drying, while the cooked rice from an electric rice cooker was washed with ambient or cool water for 30 s prior to drying. After pretreatment the cooked rice was dried either by freeze drying or hot air drying at 80 °C. Based on the scanning electron microscopic results it was found that the cooking, pretreatment and drying methods all affected the rice morphology. The hardness and stickiness of instant rice after rehydration were lower for samples prepared from the rice cooker than those of freshly cooked rice, while both textural properties appeared to be improved significantly for the samples from boiling. The texture of the freeze-dried products was not different from that of the air-dried one. The freezing pretreatment provided the texture and glycemic index of instant rice after rehydration similar to those of the freshly cooked rice. On the other hand, the cooling pretreatment resulted in the harder texture and higher glycemic index of the samples.     

Molecular mechanism underlying anti-apoptotic and anti-inflammatory effects of Mamao (Antidesma thwaitesianum Müll. Arg.) polyphenolics in human breast epithelial cells

There has been increasing interest in finding natural antioxidants to prevent free radical damage and retard the progress of chronic inflammatory diseases. Our previous data demonstrated the strong antioxidant properties of polyphenolics in Mamao seed (MS) and Mamao marc (MM) extracts. In this study we further investigated the effect of MS and MM polyphenolics on hydrogen peroxide (H₂O₂)-induced apoptosis and tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation, using human breast epithelial (MCF10A) cells. MS and MM extracts conferred dose-dependent protection against H₂O₂-induced apoptosis by inhibiting PARP/caspase-3 cleavage, inducing anti-apoptotic Bcl-2 expression, and down-regulating pro-apoptotic Bax. Moreover, MS and MM polyphenolics inhibited TPA-induced COX-2 and NF-κB activation by blocking the degradation of cytoplasmic IκBα, as well as subsequent nuclear translocation of p65 and attenuation of the activation of ERK, but not JNK and p38. These data establish the molecular mechanism for the anti-apoptotic and anti-inflammatory effects of MS and MM polyphenolics.     

A soluble fibre gel produced from rice bran and barley flour as a fat replacer in Asian foods

A hydrocolloidal fibre composite made from rice bran and barley flour, called Ricetrim, was found to have similar rheological properties to coconut cream. Coconut cream displayed a very narrow region of linear viscoelastic behaviour, both above and below strain values of 0.1%, the oscillatory shear modulus dropped sharply with increasing strain, indicating non‐linear viscoelastic behaviour. This region of linear viscoelastic behaviour extended to strains of 10%. When Ricetrim was substituted for coconut cream in Thai foods, it was found to produce acceptable products, but with lower saturated fat contents. Cookies, pumpkin pudding, layer cake, dip for pot crust, taro custard and sauté chicken curry were produced with fat contents reduced by 47.8, 94.3, 59.8, 75.3, 61.3 and 60.6%, respectively. Some differences in flavour and texture were observed at the higher levels of substitution, but these differences appeared to present only small changes in the overall score of general acceptability, or suitability, of the fibre gel foods. Scanning electron micrographs of the pumpkin pudding revealed only small changes in their surfaces with Ricetrim addition, even at higher levels of substitution.     

Study on quality attributes and drying kinetics of instant parboiled rice fortified with turmeric using hot air and microwave-assisted hot air drying

Abstract

This study investigated the quality and drying kinetics of instant parboiled rice fortified with turmeric (IPRFT) by using hot air (HA) and microwave-assisted hot air (MWHA) drying. The cooked long grain parboiled rice (LGPR) fortified with turmeric was dried with HA at temperatures of 65, 80, 95, and 110?°C. The microwave power density of 0.588 Wg^?1 was incorporated for drying with MWHA. Drying was performed until the dried IPRFT reached 16% (d.b.) of moisture content. The quality of the dried IPRFT was evaluated in terms of color, total phenolics content (TPC), total antioxidant capacity (TAC), rehydration ratio, volume expansion ratio, texture and microstructure. The results showed that the incorporation of microwave power with HA drying helped to reduce the drying time by 50% compared to conventional HA drying. A prediction of the moisture ratio by using the Page model provided the best R² and RMSE in drying kinetics. The drying conditions had small effects on the color, TPC, TAC, and microstructure of the dried IPFRT. The rehydration ratio, volume expansion ratio and texture of the rehydrated IPFRT showed minimal variations from changes in the drying conditions. The TPC and TAC of the dried IPRFT clearly increased compared to the TPC and TAC of the initial LGPR.     

Evaluation of heat treatment regimes and their influences on the properties of powder‐printed high‐density polyethylene bone implant

A two‐step heat treatment was utilized as a means to improve the mechanical properties of a high‐density polyethylene structure which was fabricated using the three‐dimensional printing technique. It was found that the relationship between structure and properties was strongly influenced by heat treatment conditions including treatment times (15–60 min) and treatment temperatures (140–180 °C) of both primary and secondary steps. The use of primary heating at 180 °C for 15 min and secondary heating at 160 °C for 60 min resulted in the highest tensile modulus and strength, 0.7 GPa and 14.8 MPa, respectively. The changes in both shrinkage and tensile properties were governed by the level of residual porosity and quality of polyethylene interface in samples which were both influenced by the degree of thermally induced densification and binder degradation. Empirical correlations between porosity and shrinkage or tensile properties were found to be power functions. Copyright © 2010 Society of Chemical Industry     

Warpage and countermeasure for injection‐molded in‐mold labeling parts

Decades ago, the production of packaging with the injection in‐mold labeling (IML) has been established. With this manufacturing technique, label and packaging, both are of the same polymeric material, become inseparably connected during the injection molding process. Because thermal conductivity of the polymeric label material is clearly smaller than that of the metal mold wall, thermal‐induced warpage of injected IML parts or part surface deformation could occur. In this study, structure and warpage behavior of IML parts, which are different from those of conventional molded parts without labels were intensively investigated. It was found that it is the volume contraction difference between label and substrate that forces IML parts to warp to the opposite side of the label. In addition, IML part warpage problem can be coped by varying the mold temperature on the stationary and moving mold platen. By increasing the mold temperature on the label side, the degree of IML part warpage can be reduced with acceptable reduction in mechanical properties. The optimum mold temperature range for particular substrate material, however, was found to be more decisive in maintaining the modulus of elasticity of IML parts than the magnitude of mold temperature difference. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Quality Attributes of Germinated High-Amylose and Waxy Rice in Superheated Steam and Hot Air Drying

In this work, the effects of amylose content, drying medium, and drying temperature on the fissure, texture, and glycemic index of germinated paddy (GP) were investigated. The amylose content, drying temperature, and drying medium affected the degree of starch gelatinization and percentage of fissure kernels significantly. Hot air drying at 130 and 150°C insignificantly influenced the hardness of Phitsanulok 2 GP with high amylose content after cooking compared to that of shade-dried GP, and the drying temperatures significantly affected the hardness and stickiness of RD6 GP without amylose content. Superheated steam drying caused a significant change in textural properties for both paddy varieties because of complete starch gelatinization. The high-amylose paddy had higher gamma-aminobutyric acid and lower glycemic index than nonamylose paddy. Drying temperature and drying media did not change the gamma-aminobutyric acid and glycemic index of both GP varieties in comparison to their shade-dried samples.     

Accelerated aging of jasmine brown rice by high-temperature fluidization technique

After being cooked, newly harvested brown rice becomes a pasty mass and swells only slightly. To modify these undesirable brown rice properties, the paddy needs to be stored for at least 3–6 months. However, problems arise since brown rice has short shelf-life (3–6 months) due to accumulation of free fatty acids (FFA) leading to rancidity during storage. In the present study, high-temperature fluidized-bed drying technique in combination with tempering step was tested to alleviate the above-mentioned problems. The quality of rice dried at temperatures of 130 and 150 °C and tempered for 30 up to 120 min was compared to that of brown rice stored at ambient temperature (approximately 30 °C) for 7 months. The experimental results showed that the cooking and eating properties of the fluidized bed dried brown rice, i.e., hardness, solid loss, volume expansion and elongation ratio, changed in a similar fashion to those of the conventionally aged brown rice. The drying temperature and tempering time affected significantly the brown rice properties. The texture of cooked thermally treated brown rice was significantly firmer than that of the conventionally aged brown rice. In addition, it was found for the thermally treated brown rice that the contents of free fatty acids increased only slightly during storage while the glycemic index reduced from high to low-medium level.     

Adaptogenic-active components from Kaempferia parviflora rhizomes

Kaempferia parviflora rhizome extracts obtained by maceration with hexane, chloroform, methanol, and ethanol were screened for their adaptogenic activities using swimming tests of mice. The effective adaptogenic extract dose was 500 mg/kg of body weight and was given orally once a day. Crude hexane extract showed significantly shorter mouse immobilisation time than those of the other and control extracts. This crude hexane extract was separated into three fractions by column chromatography. Among these fractions, the fraction rich in terpenoids possessed the highest adaptogenic activity and was comparable to that of the crude ginseng root powder used as a reference control. Therefore, terpenes contained in this fraction could be attributed to the decrease in exhaustion during the swimming of mice. There was no effect on body weight, heart, liver, kidneys, and adrenal glands of the mice. Chemical characterisation of this adaptogenic-active fraction by NMR and GC-MS showed germacene D, β-elemene, α-copaene, and E-caryophyllene as major constituents. Accordingly, these terpenes are considered the adaptogenic agents of K. parviflora rhizomes.     

Simple,Selective, and Rapid Quantification of 1-Deoxynojirimycin in Mulberry Leaf Products by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection

ABSTRACT: 1-Deoxynojirimycin (DNJ) occurs in mulberry and other plants and is a highly potent glycosidase inhibitor reported to suppress blood glucose levels, thus preventing diabetes. Derivatization is required for quantification of DNJ upon use of spectral detection methods. Because of this difficulty, the DNJ contents of mulberry-based food products are rarely stated, even if DNJ is their active component. A simple, selective, and rapid method of high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) to quantify DNJ in mulberry-based food products was developed. Stability testing of DNJ under heat treatment was also performed. A water extract of mulberry tea sample was subjected to HPAEC-PAD in a CarboPac MA1 column with a sodium hydroxide gradient. DNJ was clearly separated at a retention time of 7.26 min without interference and was selectively detected in the water extract. The detection limit was 5 ng. Heat stability studies suggested that DNJ was heat stable. HPAEC-PAD was not subject to interference, was highly selective for DNJ, and was superior to other high-performance liquid chromatography (HPLC) techniques in terms of sample preparation, resolution, and sensitivity. The method allowed simple, selective, and rapid analysis of DNJ in food matrices and might be useful for development of mulberry-based food products. Heat treatment could be an option for sterilizing mulberry-based products.