Evaluation of Quality Properties of Brown Tigernut (Cyperus esculentus L.) Tubers from Six Major Growing Regions of China: A New Source of Vegetable Oil and Starch.

Tigernut has been recognized as a promising resource for edible oil and starch. However, the research on the quality characteristics of tigernut from different regions is lagging behind, which limits the application of tigernut in food industry. Tigernut tubers were obtained from six major growing regions in China, and the physicochemical properties of their main components, oil and starch, were characterized. Tigernut tubers from Baoshan contained the most oil (30.12%), which contained the most ß-carotene (130.4 µg/100 g oil) due to high average annual temperature. Gas chromatography analysis and fingerprint analysis results indicated that tigernut oil (TNO) consists of seven fatty acids, of which oleic acid is the major component. Changchun TNO contained the least total tocopherols (6.04 mg/100 g oil) due to low average annual temperature. Tigernut tubers from Chifeng (CF) contained the most starch (34.85%) due to the large diurnal temperature range. Xingtai starch contained the most amylose (28.4%). Shijiazhuang starch showed the highest crystallinity (19.5%). Anyang starch had the highest pasting temperature (76.0°C). CF starch demonstrated superior freeze-thaw stability (syneresis: 50%) due to low mean annual precipitation. The results could be further applied to support tigernut industries and relevant researchers that looks for geographical origin discrimination and improvements on tigernut quality, with unique physicochemical and technological properties.

Impact of high temperature on microstructural changes and oil absorption of tigernut (Cyperus esculentus L.) starch: Investigations in the starch-oil model system.

This study was to explore the internal reasons for the changes in oil absorption performance of tigernut starch (TS) by revealing the high-temperature induced variations of structural and functional properties of TS. The results showed that as the temperature increased from 80 °C to 140 °C, the degree of starch gelatinization increased, while the proportion of double helix structures, the total proportion of B1 and B2 chains, the relative crystallinity and the molecular weight decreased, accompanied by the fragmentation and swelling of TS granules. The oxidation of tigernut oil (TNO) led to a decrease in oil density and an increase in total polar component content. These phenomena could result in an increase of oil absorption capacity of TS and starch-lipid complex index. With further increase in temperature from 170 °C to 200 °C, the disruption of the crystalline structure and chain structure increased, resulting in the melting and disintegration of TS granules. This caused a decrease in the starch-oil contact area and capillary absorption of TNO by the TS granules. The results will contribute to revealing the effect of high-temperature induced changes in the structural and functional properties of TS on its oil absorption properties.

Effects of temperature, relative humidity, and illumination on the entomological parameters of Aedes albopictus: an experimental study.

Aedes albopictus (Diptera: Culicidae) is a mosquito from Asia that can transmit a variety of diseases. This paper aimed to explore the effects of temperature, relative humidity, and illumination on the entomological parameters related to the population growth of Aedes albopictus, and provide specific parameters for developing dynamic models of mosquito-borne infectious disease. We used artificial simulation lab experiments, and set 27 different meteorological conditions to observe and record mosquito's hatching time, emergence time, longevity of adult females, and oviposition amount. We then applied generalized additive model (GAM) and polynomial regression to formulate the effects of temperature, relative humidity, and illumination on the biological characteristics of Aedes albopictus. Our results showed that hatchability closely related to temperature and illumination. The immature stage and the survival time of adult female mosquitoes were associated with temperature and relative humidity. The oviposition rate related to temperature, relative humidity, and illumination. Under the control of relative humidity and illumination, ecological characteristics of mosquitoes such as hatching rate, transition rate, longevity, and oviposition rate had an inverted J shape with temperature, and the thresholds were 31.2 °C, 32.1 °C, 17.7 °C, and 25.7 °C, respectively. The parameter expressions of Aedes albopictus using meteorological factors as predictors under different stages were established. Meteorological factors especially temperature significantly influence the development of Aedes albopictus under different physiological stages. The established formulas of ecological parameters can provide important information for modeling mosquito-borne infectious diseases.

Optimization and Kinetics Modeling of Microwave-Assisted Subcritical n-Butane Extraction of Tigernut Oil.

In this study, tigernut oil was extracted from tigernut meal by subcritical n-butane extraction with the assistance of microwave pretreatment. Effects of microwave pulse duration, particle size of tigernut meal, and subcritical extraction variables (temperature, time, solid-liquid ratio, number of extraction cycles) on extraction efficiency were examined by single-factor experiments and Response Surface Methodology (RSM) modeling. The results indicate that microwaving (560 W, 6 min) significantly increased the subcritical extraction efficiency. The variation of extraction yield could be interpreted as a nonlinear function of extraction time, temperature and liquid-solid ratio. Changing the independent variables could affect the oil extraction efficiency. The subcritical extraction of tigernut oil with a liquid-solid ratio of 3.62 kg/(kg of tigernut meal) at a temperature of 52°C for 32 min after three extraction cycles produced the most oil, and a maximum yield (24.736%) of tigernut oil was achieved. The ratio of unsaturated to saturated fatty acids (4.68 UFA/SFA), low acid value (3.30 mg KOH/g oil), low peroxide value (0.28 meq.kg-1), and preponderance of oleic acid indicate a high-quality oil. To describe the extraction kinetics, a modified Brunner's mathematical model was used. The model fit the experimental data well over the entire operating range, and the explanation coefficient exceeds 96%. Our results can be used to develop an optimized method for subcritical fluid extraction of tigernut oil and can move industry further toward implementing microwave-assisted subcritical extraction in oil processing.

The physicochemical properties of starches isolated from defatted tigernut meals: Effect of extrusion pretreatment.

If the tigernut meal left after oil extraction is used as a material for starch resources instead of being wasted, the industrial value of tigernut would be improved. Thus, we investigated the effect of extrusion before oil extraction on the yield, structure and function of starches within tigernut meals (TMS). Compared with the yield of native starch, the yield of TMS-130-11 (barrel temperature: 130 °C; feed moisture: 11 %) was increased by 1.97 %, and that of TMS-140-11 (barrel temperature: 140 °C; feed moisture: 11 %) was decreased by 7.82 %. The starches cannot be obtained when the barrel temperature is above 140 °C with 11 % feed moisture. Extrusion slightly decreased the relative crystallinity and increased the ratio of B2-chains in amylopectin. These changes resulted in reductions in peak viscosity while improving the elastic properties of the starch gel. These results will provide useful information regarding the use of starch isolated from tigernut meal.

Kinetic modeling of the sesamin conversion into asarinin in the presence of citric acid loading on Hß.

In the present work, effects of reaction temperature, reactant concentration, catalyst loading, and rotation speed on the kinetics of sesamin conversion in a sesame oil system were studied by using citric acid loading on Hß zeolite (CA/Hß) as a catalyst. A kinetic model was built for sesamin conversion. The kinetic model fits correctly the experimental concentration of sesamin and asarinin ( R S ⁢ e ⁢ s ⁢ a ⁢ m ⁢ i ⁢ n 2 = 0.93 and R A ⁢ s ⁢ a ⁢ r ⁢ i ⁢ n ⁢ i ⁢ n 2 = 0.97). The sesamin conversion is an endothermic reaction (△H rIso = 3 4.578kJ/mol). The CA/Hß catalyst could be easily regenerated by calcination, and there was no obvious loss of catalytic activity when reused. Knowledge of the sesamin conversion is of great significance for guiding production and improving the value and nutrition of sesame oil. In a word, this study lays the foundation for the scale-up of the production of asarinin from sesame oil using CA/Hß as the catalyst.

Pectic polysaccharides extracted from sesame seed hull: Physicochemical and functional properties.

The objective of the present investigation was to extract pectic polysaccharides from sesame seed hull and to determine their physicochemical and functional characteristics. The pectic polysaccharides in the seed hull were extracted with HCl and then collected at three ethanol concentrations of 30% (SSP30), 50% (SSP50), and 90% (SSP90). We found that SSP30 represented 75.6% of the total polysaccharides, and that it contained 76.39% galacturonic acid, with many HG domains and few short side chains in the RG-I domains. SSP30 exhibited the strongest hydroxyl radical scavenging activity among the three fractions, and was better able to stabilize the emulsions. Higher Mw pectic polysaccharides were firstly precipitated at lower ethanol concentrations, and the Mw of the precipitated pectic polysaccharides decreased with increasing ethanol concentration. These results provide important information on the structure and functional characteristics of sesame hull polysaccharides. This information can contribute to the future development of sesame hull polysaccharides for industrial purposes.

Spatiotemporal heterogeneity of social contact patterns related to infectious diseases in the Guangdong Province, China.

The social contact patterns associated with the infectious disease transmitted by airborne droplets or close contact follow specific rules. Understanding these processes can improve the accuracy of disease transmission models, permitting their integration into model simulations. In this study, we performed a large-scale population-based survey to collect social contact patterns in three cities on the Pearl River Delta of China in winter and summer. A total of 5,818 participants were face-to-face interviewed and 35,542 contacts were recorded. The average number of contacts per person each day was 16.7 considering supplementary professional contacts (SPCs). Contacts that occurred on a daily basis, lasted more than 4 hours, and took place in households were more likely to involve physical contact. The seasonal characteristics of social contact were heterogeneous, such that contact in the winter was more likely to involve physical contact compared to summer months. The spatial characteristics of the contacts were similar. Social mixing patterns differed according to age, but all ages maintained regular contact with their peers. Taken together, these findings describe the spatiotemporal distribution of social contact patterns relevant to infections in the Guangdong Province of China. This information provides important parameters for mathematical models of infectious diseases.

Gastrointestinal absorption, antiproliferative and anti-inflammatory effect of the major carotenoids of Gardenia jasminoides Ellis on cancer cells.

The gastrointestinal absorption of the main carotenoids present in Gardenia jasminoides Ellis, crocetin, crocin-1 and crocin-2, was assayed through transport studies on MKN-28 and Caco-2 cell lines. Overall, crocetin was the compound that presented the highest gastrointestinal transport efficiency. Additionally, and since after absorption crocins are metabolized into crocetin, the antiproliferative capacity of crocetin was assayed in MKN-28 (stomach), MCF-7 (breast) and Caco-2 (colon) cancer cell lines. The results point to an antiproliferative effect of crocetin on the three cell lines tested. Anti-inflammatory properties were also assayed. Overall, crocetin showed a potential involvement in the downregulation of IL-1ß and TNF-α but not IL-6. Altogether, these results suggest that these compounds can have an important role against cancer proliferation, highlighting the importance of Gardenia jasminoides Ellis as a nutraceutical food source.

Optimization of ultrasound-assisted extraction of gardenia fruit oil with bioactive components and their identification and quantification by HPLC-DAD/ESI-MS(2).

Compounds in Fructus Gardeniae have been shown to possess a wide array of biological activities. However, Gardenia oil extracted from its fruit is less reported and its composition remains uncertain. To completely characterize lipophilic compounds in Gardenia oil, three conventional extraction (CE) and ultrasound-assisted extraction (UAE) methods were investigated. The oil extraction yield obtained by UAE was 51.8% higher than that acquired by cold-pressed extraction (CPE). The fatty acid profile in UAE oil with different solvents was characterized by GC-MS. Petroleum ether was observed to be an ideal solvent with 8.59% extraction yield and 78.88% recovery rate and with a ratio of 3.11 of unsaturated fatty acids to saturated fatty acids. Response surface methodology (RSM) with Box-Behnken Design (BBD) was applied to optimize conditions in UEA of oil to maximize extraction yield. Furthermore, the bioactive components in oil extracted by UAE were qualitatively identified and quantified by HPLC-DAD/ESI-MS(2) and HPLC-DAD analysis. The eight compounds in Gardenia oil, including geniposide, trans/cis-crocin-1, crocin-2, crocin-3, crocin-4, and trans/cis-crocetin, were structurally revealed. The corresponding transfer rates of the bioactive components showed that the lipophilic trans/cis-crocetin could be completely transferred from fruit to oil, with the highest concentration of 11.38 µg g(-1) oil among all compounds quantified. These findings could deliver potential application to a large-scale production of functional Gardenia oil whose bioactive components possess health benefits.