Semi-batch extraction of anthocyanins from red grape pomace in packed beds: experimental results and process modelling

A semi-batch extraction process of anthocyanins was studied in a packed bed. Methanol was used as solvent and the raw material studied consisted of skins of the tempranillo grape, which was obtained from the pomace from red wine vinification. The results show large diffusional effects due to strong control from the mass transfer. The best results were obtained using a high temperature and a high flow rate. A penetration model is proposed in terms of a bed of spherical particles. The model provides a value for the diffusion coefficient of the solute within the solid matrix. It can be seen that the adjustment of the model is satisfactory and that it is able to predict, to a reasonable extent, the yield of the extraction process.     

Antioxidant Capacity of Rapeseed Extracts Obtained by Conventional and Ultrasound‐Assisted Extraction

Ultrasound‐assisted extraction (UAE) and conventional solid–liquid extraction were applied to extract total antioxidants from two rapeseed varieties. The antioxidant capacities (AC) of winter and spring rapeseed cultivars were determined by four different analytical methods: ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS). The average AC of the studied rapeseed cultivars ranged between 4.21–10.03 mmol Trolox (TE)/100 g, 7.82–10.61 mmol TE/100 g, 8.11–51.59 mmol TE/100 g, 22.48–43.13 mmol TE/100 g for FRAP, CUPRAC, DPPH and ABTS methods, respectively. There are positive correlations between total phenolics (TPC = 804–1625 mg sinapic acid (SA)/100 g) and AC of the studied rapeseed extracts (r = 0.2650–0.9931). Results of the principal component analysis (PCA) indicate that there are differences between the total amounts of antioxidants in rapeseed samples extracted by different extraction techniques. Rapeseed extracts obtained after 18 min of ultrasonication revealed the highest content of total antioxidants. The UAE is a very useful, efficient and rapid technique of oilseed samples preparation for determination of AC by different analytical methods.     

迷迭香酸的提取及抗氧化活性测定

研究了用乙醇从迷迭香中提取迷迭香酸的工艺,同时,利用Fonton方法测定了迷迭香酸的抗氧化活性。结果表明,乙醇提取迷迭香酸的最佳体积分数为50%,迷迭香酸具有很好的抗氧化活性。该工艺为工业化、大规模生产迷迭香酸提供了一定的实验基础和借鉴。     

Modeling the Kinetics of Antioxidant Extraction from Origanum vulgare and Brassica nigra

In the present research work, the effect of solvents, particle size, solvent/solid ratio, and temperature on the extraction efficiency of oregano (Origanum vulgare) and mustard (Brassica nigra) were investigated. The extraction process proceeded at a fast rate followed by a slower one. Particle size, solvent type, solvent/solid ratio and temperature had a positive effect on the extraction process, and maximum extraction was achieved by ethanol. Extraction kinetics was determined with a mathematical model derived from Fick's second law. The results were verified with Fick's diffusion model for extraction kinetics in all experiments, which provided the initial rate and extent of solid–liquid extraction. Antioxidant values were determined using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2′-azino-Bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The extracts of O. vulgare and B. nigra prepared using ethanol showed optimal antioxidant activity.     

Carbon mineralization from composts and food industry wastes added to soil

We have studied the short term C mineralization of six wastes from important food industries, one sludge from a biogas plant and three composts. All the wastes were characterized chemically and fractionated according to the Van Soest method. The fresh wastes were incubated under controlled environment conditions to determine the C mineralization rate. Based on first order mineralization kinetics, we calculated the hypothetical amount of stable C in the wastes as the amount of C that would not be mineralized within one year under field conditions. The percentage of stable organic C in the organic matter was in general much larger in the composts than in the other wastes, but when expressed on dry matter, the non-composted wastes had comparable or larger amounts of stable organic C than the composts and have a considerable potential for supplying organic matter to soils, and hence for C sequestration. The amount of stable organic C could best be predicted by the total N content of the wastes (R _a ² = 0.855), whereas the results of the fractionation had very little predictive power, probably due to problems related to the high ash content of some of the wastes. An index that combined stable organic C and N and P content in the wastes was calculated to assess possible limitations for applying these wastes in agriculture. Under current nutrient legislation in Western Europe, a number of these wastes will only be usable in small amounts, but these and other food industry wastes could still prove to be valuable soil amendments in nutrient poor situations, for increasing soil organic C content and supplying nutrients.     

Kinetics of ultrasound assisted extraction of anthocyanins from Aronia melanocarpa (black chokeberry) wastes

Black chokeberry fruits are very rich in antioxidant phenolics. After juice extraction, the wastes of pressed berries (juice production by-products) still contain important amount of phenolic species and namely anthocyanins. Ultrasound assisted extraction (UAE) from such wastes was studied. The influence of extraction time (0–240 min), temperature (20–70 °C), solvent composition (0–50% ethanol in water) and ultrasound power (0–100 W) on anthocyanins and polyphenols yields and on antioxidant capacity of the extracts was studied. High temperature and ethanol content in the solvent improved greatly the extraction yields. Ultrasounds improved mainly the extraction kinetics. Ultrasound effect was higher in the beginning of extraction process and at low temperatures. Suitability of UAE for preparation of antioxidant-rich plant extracts at reduced time and energy was confirmed obtaining high extraction efficiencies and high antioxidant capacities of Aronia extracts. To optimize extraction conditions a kinetic mathematical model, based on Peleg's equation and considering also the rate of anthocyanins thermal degradation, was proposed. The influences of extraction time, temperature, solvent composition and ultrasound power on polyphenols and anthocyanins yields and on antioxidant capacity were considered. The optimal conditions for anthocyanins extraction predicted by this model were experimentally validated.     

Supercritical carbon dioxide essential oil extraction of Lamiaceae family species: Mathematical modelling on the micro-scale and process optimization

In this paper the essential oil supercritical carbon dioxide extraction from leaves of Lamiaceae family species was studied. Recent investigations of Lamiaceae family essential oil storage have shown that most of the oil is found in peltate glandular trichomes on the leaf surface. The effect of supercritical CO₂ on the peltate glands was investigated by Scanning Electron Microscopy. It was observed that exposure to supercritical CO₂ led to disruption of the peltate glands and essential oil release. This phenomenon was used as a basic hypothesis of the mathematical model of the supercritical fluid extraction with CO₂. The model was applied to simulate basil, rosemary, marjoram and pennyroyal supercritical CO₂ extraction on the existing experimental data. An average deviation from the experimental data was less than 0.83%. The model results indicated a possibility of a decrease in the supercritical CO₂ consumption by modified and optimized processing of Lamiaceae family herbaceous material.     

Co-gasification study of biomass mixed with plastic wastes

Fluidised bed steam gasification has proven to be a possible way of converting biomass and plastic undesirable wastes into fuel gases. The addition of plastics to pine wastes decreased CO content, but increased H₂ released, up to values of 50% (v/v). The highest gas yield obtained was 1.96 Nl/g daf for 98% of energy conversion, when 60% (w/w) of plastic was in the feedstock. The steam/waste mixture ratio seems to have a small effect on gas composition. Temperature is the parameter that most influenced gases composition. The rise of temperature favoured the formation of H₂ and decreased the formation of hydrocarbons, tars and char. At 885°C and in presence of 40% (w/w) of plastic, conversion to char was around 2%, whilst feedstock conversion to gas was around 90%. In this paper, the effect of experimental conditions on gasification process, with the aim of enhancing the gas production and improving its composition and energetic content was analysed.     

Optimization of the Drying Process of Carrot (Daucus carota v. Nantes) on the Basis of Quality Criteria

The drying curves and the degradation kinetics of three different quality attributes (total carotenoids (TC) and total polyphenols (TP) contents and antioxidant activity (AA)) of carrots during drying at different temperatures (from 40 to 90°C) have been experimentally evaluated and modeled. A diffusional model taking into account the solid shrinkage and both the external and internal water transfer resistances was used to accurately represent the water transfer in carrot during drying (average mean relative error (MRE) of 3.3 ± 0.6%). The effective moisture diffusivity was found to follow the Arrhenius relationship (E_a = 76.0 kJ/mol) and the mass transfer coefficient a linear dependence with air temperature. The Weibull model was used to satisfactorily simulate the degradation kinetics of the three quality attributes considered (average MRE of 2.8 ± 1.2% for TC content, 5.7 ± 1.0% for TP content, and 3.6 ± 1.8% for AA); these were the E_a of 52.7 kJ/mol for TC; 22.1 kJ/mol for TP; and 27.5 kJ/mol for AA kinetics. By using the proposed models, the estimated optimum drying temperature to best retain the total carotenoids content ranged between ca. 42–46°C; meanwhile, in order to maintain the TP content and the antioxidant activity at the highest levels, the drying needed to be carried out at temperatures of ca. 60–75°C. These results indicate that the TC retention is more influenced by the drying temperature, while the TP and AA retentions are more sensitive to drying time exposure. However, it was possible to establish a global optimum air temperature which ranged between 52.6 and 57.7°C, decreasing the TC, TP, and AA retentions by less than 2.2% from their respective optimal values.     

灰绿藜叶总黄酮提取与测定及抗氧化活性研究

通过紫外-可见分光光度法,结合方法学研究,得到优化的灰绿藜叶黄酮含量测定方法;在此基础上采用单因素和响应面试验优化微波提取灰绿藜叶黄酮的工艺条件,同时研究了灰绿藜叶黄酮对?OH 及O2-?的清除效果。结果表明,以3%AlCl3在273.5nm下测定的灰绿藜叶黄酮含量的方法是合适的,该法的稳定性、重复性、精确度、回收率均较好,其RSD分别为：1.42%、1.83%、0.86%和0.60%;微波提取灰绿藜叶黄酮的最佳提取条件为: 乙醇体积分数57%,液料比20:1,微波功率500W,微波时间7.8min,在此工艺条件下,灰绿藜叶黄酮得率为3.292%。灰绿藜叶黄酮对?OH 及O2-?具有较好清除作用, 抗氧化能力与灰绿藜叶黄酮的含量呈正相关关系。     

Colored and White Sectors From Star-Patterned Petunia Flowers Display Differential Resistance to Corn Earworm and Cabbage Looper Larvae

Anthocyanins are likely a visual aid that attract pollinators. However, there is also the possibility that anthocyanins are present in some flowers as defensive molecules that protect them from excess light, pathogens, or herbivores. In this study, resistance due to anthocyanins from commercial petunia flowers (Petunia hybrida) was examined for insecticide/antifeedant activity against corn earworm (CEW, Helicoverpa zea) and cabbage looper (CL, Trichoplusia ni). The petunia flowers studied contained a star pattern, with colored and white sectors. CEW larvae ate significantly less colored sectors than white sectors in no-choice bioassays in most cases. All CEW larvae feeding on blue sectors weighed significantly less after 2 days than larvae feeding on white sectors, which was negatively correlated with total anthocyanin levels. CL larvae ate less of blue sectors than white sectors, and blue sectors from one petunia cultivar caused significantly higher CL mortality than white sectors. Partially purified anthocyanin mixtures isolated from petunia flowers, when added to insect diet discs at approximately natural concentrations, reduced both CEW and CL larva weights compared to the controls. These studies demonstrate that the colored sectors of these petunia cultivars slow the development of these lepidopteran larvae and indicate that anthocyanins play some part in flower defense in petunia.     

Extraction of flavonoids and carotenoids from Thai silk waste and antioxidant activity of extracts

Extraction of carotenoids and flavonoids from yellow Thai silk waste was investigated. The total recovery of 0.7 mg carotenoids and 5.1 mg flavonoids/g dry weight was obtained by ethanol extraction. Different methods for extractions of these pigments were carried out using two benign solvents: ethanol and subcritical water (SW) to determine the extraction efficiency of the solvents in various extraction conditions. For extraction of carotenoids, ethanol was suitable as extraction solvent and the amount of carotenoids increased with increasing temperature and extraction time. For flavonoids, SW extraction was suitable but the amount of flavonoids decreased with increasing SW temperature and extraction time due to decomposition at such conditions. In addition, the silk extracts were found to have low IC₅₀ values (15.6–23.3 μg/ml), the concentrations of the silk extracts that exhibit 50% reduction in 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), (ABTS) free radicals, thus indicating high antioxidant activities.     

Response surface methodology optimization applied to rubber tyre and plastic wastes thermal conversion

Thermal degradation was studied as a method to decompose mixtures of rubber tyre (RT) and different plastic wastes (PE, PP and PS) with the aim of producing a liquid fuel [1], as well as valuable chemical raw materials. An experimental set of runs was performed to establish the operational conditions that maximize liquid fraction production in a 1 litre batch reactor. Waste blends used were composed of 30% w/w RT and 70% w/w plastics (20% PE, 30% PP and 20% w/w PS). The complex hydrocarbon liquid mixture obtained during pyrolysis of these residues was highly dependent on experimental parameters, namely temperature, initial pressure and reaction time, which are the three most important factors affecting liquid yields. Regression analyses of experimental data were performed according to response surface methodology (RSM). As a result, experimental conditions optimized based on Factorial Design Methodology were 370 °C, 0.48 MPa for initial pressure and 15 min for reaction time. In order to validate the results obtained by the RSM model, three extra runs were conducted sequentially and average values were calculated and found to be: gas yield of 4.9% w/w, liquid yield of 81.3% w/w and solid yield of 12.7% w/w with an experimental deviation of 0.95%.     

超临界萃取生姜中姜油的研究

研究了应用超临界二氧化碳萃取生姜的工艺条件,结合萃取压力、温度、时间,物料水分、粒度等参数对萃取率的影响。采用单因子变化的实验方法,得出生姜萃取率的最佳工艺条件为：压力20MPa,温度40℃,二氧化碳流量20L／h,时间2h。