Bhalang Suriharn

Anthocyanin, phenolics and antioxidant activity changes in purple waxy corn as affected by traditional cooking

Antioxidant components, including anthocyanins and phenolic compounds, antioxidant activity, and their changes during traditional cooking of fresh purple waxy corn were investigated. As compared to the raw corn, thermal treatment caused significant (p⩽0.05) decreases in each antioxidant compound and antioxidant activity. Steam cooking preserved more antioxidant compounds than boiling. Boiling caused a significant loss of anthocyanin and phenolic compounds into the cooking water. This cooking water is a valuable co-product because it is a good source of purple pigment. By comparing levels of antioxidant compounds in raw and cooked corn, we determined that degradation results in greater loss than leaching or diffusion into cooking water. Additionally, separation of kernels from the cob prior to cooking caused increased loss of antioxidant compounds.

Changes in physicochemical properties of waxy corn starches at different stages of harvesting.

Starches were isolated from immature waxy corn kernels harvested at 0, 2, 4 and 6 days after optimum stage (DAO) and from mature kernels at 16 DAO. The starch contents showed varied according to genotypes and harvesting stages. The accumulation of starches showed an increasing trend in relation to delayed harvesting time, from the optimum stage until the physiological maturity stage. Among all harvesting stages, medium granules had the highest contribution to the total starch volume (60.8-81.5%), followed by large (5.7-30.1%), and small granules (9.1-15.3%). Average chain length distribution of amylopectin ranged from DP 14.7 to 16.9 for KKU-UB, DP 16.9 to 17.4 for KKU-JD, and DP 5.7 to 30.1 for Violet white. The pasting behaviors of starches were greatly affected by harvesting times. The peak viscosity of starches increased with delayed harvesting until physiological maturity and then decreased until dried kernels at 35 days after pollination.

Preventive Effect of Zea mays L. (Purple Waxy Corn) on Experimental Diabetic Cataract

Recently, substances possessing antioxidant can prevent cataractogenesis of diabetic cataract. Therefore, this study was carried out to determine the anticataract effect of Zea mays L. (purple waxy corn), a flavonoids rich plant, in experimental diabetic cataract. Enucleated rat lenses were incubated in artificial aqueous humor containing 55 mM glucose with various concentrations of Zea mays L. (purple waxy corn) ranging between 2, 10, and 50 mg/mL at room temperature for 72 h. At the end of the incubation period, the evaluation of lens opacification, MDA level, and the activities of SOD, CAT, GPx, and AR in lens were performed. The results showed that both medium and high doses of extract decreased lens opacity together with the decreased MDA level. In addition, medium dose of extract increased GPx activity while the high dose decreased AR activity. No other significant changes were observed. The purple waxy corn seeds extract is the potential candidate to protect against diabetic cataract. The mechanism of action may occur via the decreased oxidative stress and the suppression of AR. However, further research in vivo is still essential.

Influence of variety and harvest maturity on phytochemical content in corn silk

Corn silk has been used as a traditional herb in Asia. The objective of this study was to evaluate variability in phytochemicals in corn varieties at three maturity stages of corn silk. Ten vegetable corn varieties were evaluated in a completely randomized design with three replications. Data were recorded for total phenolic (TPC), total flavonoids (TFC), total anthocyanin (TAC) and antioxidant activity (AA) by DPPH free-radical-scavenging assays. Differences among corn varieties were observed for all parameters at all maturity stages, and the interactions between maturity stage and corn variety were significant. TPC and TAC were highest at the milky stage, whereas TFC and AA were highest at the silking stage. TPC, TFC and AA were highest in super sweet corn and white corn at the silking stage. PWC5 variety of purple waxy corn at the milky stage had the highest values for all parameters, and it is useful for further development of functional food products.

The Combined Extract of Purple Waxy Corn and Ginger Prevents Cataractogenesis and Retinopathy in Streptozotocin-Diabetic Rats

Based on the crucial roles of oxidative stress and aldose reductase on diabetic complications and the protective effect against diabetic eye complication of purple waxy corn and ginger (PWCG) together with the synergistic effect concept, we aimed to determine anticataract and antiretinopathy effects of the combined extract of purple waxy corn and ginger (PWCG). The streptozotocin diabetics with the blood glucose levels >250 mg·dL−1 were orally given the extract at doses of 50, 100, and 200 mg/kg·BW−1 for 10 weeks. Then, lens opacity and histopathology of retina were determined. The changes of MDA together with the activities of SOD, CAT, GPx, and AR in lens were also determined using biochemical assays. All doses of PWCG decreased lens opacity, MDA, and AR in the lens of diabetic rats. The elevation of CAT and GPx activities was also observed. The antiretinopathy property of the combined extract was also confirmed by the increased number of neurons in ganglion cell layer and thickness of total retina and retinal nuclear layer in diabetic rats. PWCG is the potential functional food to protect against diabetic cataract and retinopathy. However, further studies concerning toxicity and clinical trial are still essential.

The Combined Extract of Zingiber officinale and Zea mays (Purple Color) Improves Neuropathy, Oxidative Stress, and Axon Density in Streptozotocin Induced Diabetic Rats.

Based on the protective effect of the combined extract of purple waxy corn and ginger (PWCG) on oxidative stress related disorders in diabetic condition, we aimed to determine the effect of PWCG on the functional, biochemical, and structural change of the lesion nerve in streptozotocin- (STZ-) diabetic rats. PWCG at doses of 100, 200, and 300 mg·kg−1 BW were orally given to STZ-diabetic rats which were subjected to chronic constriction (CCI) at right sciatic nerve for 21 days. The blood sugar was assessed before and at the end of study whereas the sciatic function index (SFI), paw withdrawal threshold intensity (PWTI), and paw withdrawal latency (PWL) were assessed every 3 days until the end of study. At the end of study, the determination of nerve conduction velocity (NCV), axon density, oxidative stress status, and aldose reductase (AR) activity of the lesion nerve were performed. It was found that PWCG improved SFI, PWTI, PWL, and NCV together with the improved oxidative stress status and the axon density in the lesion nerve. No changes of AR activity or blood sugar level were observed. Therefore, PWCG might improve the functional and structural changes in STZ-diabetic rats plus CCI via the improved oxidative stress status.

Changes in physicochemical properties of waxy corn starches after harvest, and in mechanical properties of fresh cooked kernels during storage

Changes in the physicochemical properties of waxy corn starches after harvest and in the mechanical properties of cooked fresh kernels during storage were investigated. Immature waxy corn ears from four genotypes were stored at ambient temperature, and starches were isolated from kernels removed at 0, 2, 4 and 6 days after harvest. Starch content in the kernels generally increased with storage time, and also significantly differed depending on the genotype. For all the days after harvest, medium granules had the highest contribution to the total starch volume, followed by small and large granules. The average chain length distribution of amylopectin increased in relation to storage time. Starches at harvesting state exhibited the lowest peak viscosity in all four genotypes, which increased relative to postharvest periods. Moreover, the average force behaviours of cooked kernels were greatly affected by storage times after cooking.

Types of gene effects governing the inheritance of oleic and linoleic acids in peanut ( Arachis hypogaea L.)

Oleic and linoleic acids are major fatty acids in peanut determining the quality and shelf-life of peanut products. A better understanding on the inheritance of these characters is an important for high-oleic breeding programs. The objective of this research was to determine the gene actions for oleic acid, linoleic acid, the ratio of oleic to linoleic acids (O/L ratio) and percentage oil (% oil) in peanut. Georgia-02C, SunOleic 97R (high-oleic genotypes) and KKU 1 (low-oleic genotypes) were used as parents to generate P 1 , P 2 , F 2 , F 3 , BC 11 S and BC 12 S. The entries were planted in a randomized complete block design with four replications in the rainy season (2008) and the dry season (2008/2009). Gas liquid chromatography (GLC) was used to analyze fatty acid compositions. The data were used in generation means analysis to understand gene effects. The differences in season, generation and generation X season interactions were significant for oleic acid in the crosses Georgia-02C X KKU 1 and SunOleic 97R X KKU 1. Additive, dominance and epistasis gene effects were significant for oleic acid, linoleic acid, O/L ratio and % oil. Initial selection can be carried out in early segregating population, and final selection in late generations. Keywords: Breeding, gene actions, generation mean analysis, groundnut, oil quality

Light intensity affects capsaicinoid accumulation in hot pepper ( Capsicum chinense Jacq.) cultivars

Strong light intensity affects plant growth, fruit yield, and accumulation of capsaicinoids in hot peppers (Capsicum spp.) which are important food and medicinal products. Shading improves plant growth and fruit yield in bell pepper (Capsicum annuum), but research on the effect of shading on high pungency C. chinense cultivars is limited. This study investigated the responses of C. chinense cultivars to different light intensities to maximize capsaicinoid production. An experiment to test the effect of shading, i.e., no-shading (full light intensity as control), 50% shade and 70% shade of full light intensity, was conducted in a plastic-net house using four C. chinense cultivars with different pungency levels: Bhut Jolokia, Akanee Pirote, Orange Habanero, and BGH1719. The cultivars showed different capsaicinoid production levels depending on the shade level. The highest capsaicinoid yields were found in the F1 hybrid cultivar Akanee Pirote under 50% shading (4,820 mg/plant) and in the Bhut Jolokia cultivar under 70% shading (3,419 mg/plant). By contrast, the BGH1719 plants showed the lowest capsaicinoid production (291 mg/plant) when shade was applied. These results demonstrate that capsaicinoid production in the studied cultivars is affected by light intensity. It is recommended that growers of high pungency cultivars use the appropriate level of shading for the particular cultivar to increase capsaicinoid yield.

Influence of water stresses on capsaicinoid production in hot pepper (Capsicum chinense Jacq.) cultivars with different pungency levels

Although water stress reduces fruit yield, it also increases capsaicinoid accumulation in hot pepper. The aim of this study was to investigate the effect of different water regimes on capsaicinoid production in Capsicum chinense Jacq. having different pungency levels. Four hot pepper (C. chinense) cultivars were planted with four water regimes after anthesis: daily irrigation (control; S1), every 2 days (S2), every 3 days (S3) and every 4 days (S4). The results found that Akanee Pirote with the S2 treatment gave the highest capsaicinoid yield, and the increase of capsaicinoid yield was attributed from increasing the absolute capsaicinoid content and reducing the dry fruit yield as compared to the control. Capsaicinoid yield of Bhut Jolokia, Orange Habanero, and BGH1719 responded to the water stresses, but produced less capsaicinoid yield as compared to the control. This study reveals that appropriate water stress could increase capsaicinoid yield in some, but not all, hot pepper cultivars.