Free radical-scavenging activity of Aloe vera (Aloe barbadensis Miller) extracts by supercritical carbon dioxide extraction

The free radical-scavenging activities of extracts of Aloe vera of leaf skin by supercritical CO₂ extraction and solvent extraction were determined. An orthogonal array design matrix of L₉ (3⁴) was considered to optimize supercritical carbon dioxide extraction processing at a CO₂ flow rate of 12–36 l h⁻¹, 35–45 MPa and 32–50 °C. The optimum extracted yield of 1.47% was provided at 50 °C 36 l h⁻¹, 35 MPa and 20% of modifier of methanol. These four factors were all demonstrated to be significantly crucial in the supercritical carbon dioxide extraction operation, as two-variable interactions. The extracts of A. vera rind by supercritical carbon dioxide extraction and solvent extracts provided significantly higher free radical-scavenging activities of 33.5% and 39.7%, respectively, than extracts of A. vera gel extracted by ethanol with a free radical-scavenging activity of 14.2%. The inhibition percentage of extracts of A. vera and reference antioxidants followed the decreasing order: Trolox (76.8%) > ethanol extracts of A. vera skin (39.7%) > BHT (35.9%) > the extract of supercritical carbon dioxide extraction (33.5%) >α-tocopherol (25.6%) > ethanol extracts of A. vera pulp (14.2%). Compared to BHT and α-tocopherol, the extracts of A. vera skin, by supercritical carbon dioxide extraction and ethanol, showed stronger antioxidant activities. Components in the rind of A. vera are responsible for the higher antioxidant activity of A. vera extracts.     

Effect of high hydrostatic pressure on functional properties and quality characteristics of Aloe vera gel (Aloe barbadensis Miller)

The aim of this study was to evaluate the effects of high hydrostatic pressure treatment at three pressure levels (300, 400 and 500 Mpa) on the functional and quality characteristics of Aloe vera gel including vitamin C and E, aloin, minerals, phenolic content and antioxidant activity. The results show that HHP exerted a clear influence on minerals content, vitamin C and E content, antioxidant activity, total phenolic and aloin content. After 35 days of storage all treated samples presented a decrease in mineral content, except for phosphorus. Total phenolic content and vitamin C and E content decreased at high pressures (500 MPa), while all pressurised samples showed a higher antioxidant activity and aloin content than untreated sample after 35 days of storage. The maximum values of antioxidant activity and aloin were 6.55 ± 1.26 μg/ml at 300 MPa and 24.23 ± 2.27 mg/100 g d.m. at 400 MPa.     

Effect of High Pressure Processing on Rheological Properties,Pectinmethylesterase Activity and Microbiological Characteristics of Aloe Vera (Aloe barbadensis Miller) Juice

Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheological properties, pectinmethylesterase (PME) enzyme activity and microbiological characteristics of aloe vera juice was studied. A quadratic model was developed for rheological parameters and it was found that pressure level had the most significant effect on all the responses (p < 0.05) followed by pH and dwell time. Pectinmethylesterase activity was evaluated and a maximum of up to 30% inactivation was obtained. Microbial analysis of high pressure treated samples revealed that samples treated at 400 MPa for 20 min at pH 4 reduced microbial counts to <10 cfu mL^?1 achieving up to 5.66 log cycle reduction.     

Osmotic dehydration of Aloe vera (Aloe barbadensis Miller)

Aloe vera possess immunomodulatory, anti-inflammatory, antibacteria effects and wound and burn healing properties, but it is a very unstable product due to its high water content. Osmotic dehydration can be used to obtain stable products from aloe. In this work the effect of osmotic dehydration (OD) on Aloe vera (Aloe barbadensis Miller) leaves was studied. Peeled and unpeeled Aloe vera slices (15 × 50 mm), were immersed in sucrose solutions at 35, 50 and 65 °Brix at 25 and 40 °C. Moisture, effective diffusion coefficients and mass fluxes (water loss, solids gained and weight reduction) were determined. Osmotic dehydration experiments were conducted at atmospheric pressure. The best conditions for the OD of Aloe slices with the highest effect on diffusivity were obtained using a temperature of 40 °C for peeled samples. The analysis of the effect of temperature on mass transfer kinetics showed that unpeeled samples were more effected than peeled samples.     

大孔吸附树脂纯化库拉索芦荟中芦荟苷的研究

通过对芦荟苷的静态吸附和动态洗脱实验,对6种大孔吸附树脂进行了筛选。结果表明:HZ-801型树脂吸附与洗脱效果最佳。优化出的最佳工艺参数为:在上样浓度为0.2765mg/ml的条件下,上样体积为520ml、洗脱剂60%乙醇、洗脱速度2ml/min、洗脱体积3倍柱床体积。纯化倍数为14.72,回收率86.3%。     

Effect of high hydrostatic pressure pretreatment on drying kinetics, antioxidant activity, firmness and microstructure of Aloe vera (Aloe barbadensis Miller) gel

The effect of High Hydrostatic Pressure (HHP) and other pretreatments on the drying kinetics, antioxidant activity, firmness and microstructure of Aloe vera gel was investigated during convective drying at 70 °C. The pretreatments analyzed were high hydrostatic pressure, blanching, enzymatic and microwaves. Simulation of drying curves was studied through the application of several mathematical models such as Newton, Henderson and Pabis, Page, Modified Page, Wang and Singh, and Weibull. Among them, the Weibull model provided the best fit for the experimental data. All pretreatments increased the water diffusion coefficient compared to the control sample. Microwaves followed by HHP presented the fastest drying rates. All pretreatments modified the microstructure and hence the texture of the product. HHP and microwaves increased firmness while blanching and enzymatic treatments produced a softer final product. Blanching, microwaves and HHP enhanced A. vera antioxidant activity. However, the HHP pretreated samples showed the highest antioxidant activity compared to the rest. Based on these results, HHP together with convective drying offers the chance of producing dried aloe with high antioxidant attributes.     

Functional properties of pasteurized samples of Aloe barbadensis Miller: Optimization using response surface methodology

Functional properties (FPs) of pasteurized extracts of Aloe barbadensis Miller, rich in bioactive polymer acemannan and cell wall polysaccharides, were optimized using response surface methodology. Box–Behnken design was applied to evaluate the effects of three independent variables: age of plant (X₁ = 3–5 years), pasteurization temperature (X₂ = 65–85 °C), and pasteurization time (X₃ = 15–35 min) on swelling (Sw), water retention capacity (WRC), and fat adsorption capacity (FAC). Analysis of variance showed that the contribution of quadratic models was significant for the responses. From response surface plots, age of plant, time and temperature exhibited independent and interactive effects on Sw, WRC and FAC properties. The optimal conditions to obtain alcohol insoluble residues (AIRs) from pasteurized samples with the highest values for the FPs analysed were: (1) X₁ = 3.6 years, X₂ = 65 °C, X₃ = 15 min for Sw; (2) X₁ = 4.0 years, X₂ = 75.3 °C, X₃ = 20.5 min for WRC; (3) X₁ = 4.0 years, X₂ = 70.1 °C, X₃ = 15 min for FAC. These optimum conditions allowed the obtention of AIRs from pasteurized aloe samples exhibiting: (1) Sw of 308.0 mL g^?1 AIR; (2) WRC of 30.0 g H₂O g^?1 AIR; and (3) FAC of 33.9 g Oil g^?1 AIR. A close agreement between experimental and predictive values was found. These results may be used for the pasteurization process of A. barbadensis Miller in industry.     

Microbiological and lipid oxidation studies on mechanically deboned turkey meat treated by high hydrostatic pressure

Mechanically deboned turkey meat was treated by high hydrostatic pressure. Two treatments were applied, 200 MPa (20 min) for chilled, 400 MPa (20 min) for frozen meat, thawed-up for the treatment, then re-frozen for storage. In both cases, storage experiments were made (15 days and 8 months respectively). The changes in microbiological status and lipid oxidation parameters, as well as cholesterol oxidation products (COPs) concentration were examined. These factors could affect the shelf life, the safety and sensory quality of products. Due to the effects of treatments, a significant reduction in the numbers of viable cells, an increase in thiobarbituric acid reactive substances (TBARs) values and formation of COPs could be observed.     

Microbiological food safety assessment of high hydrostatic pressure processing: A review

High hydrostatic pressure (HHP) processing as a novel non-thermal method has shown great potential in producing microbiologically safer products while maintaining the natural characteristics of the food items. Scientific research of the process and its industrial applications has been widespread in the past two decades with many scientific publications describing its uses, advantages and limitations. The review describes the effect of HHP on foodborne pathogenic microorganisms, their structures and adaptive mechanisms, the intrinsic and extrinsic factors that affect its application with a focus on microbiological safety, and research needs. In a risk assessment context, tools and mechanisms in place to monitorize, optimize and validate the process, and procedures for assessing and modelling the lethal effect of the treatment are reviewed.     

Food processing by high hydrostatic pressure

The use of high hydrostatic pressures (HHP) for food processing is finding increased application within the food industry. One of the advantages of this technology is that because it does not use heat, sensory, and nutritional attributes of the product remain virtually unaffected, thus yielding products with better quality than those processed traditional methods. HHP have the ability to inactivate microorganisms as well as enzymes responsible for shortening the life of a product. In addition to lengthening the shelf-life of food products, HHP can modify functional properties of components such as proteins, which in turn can lead to the development of new products. Equipment for large-scale production of HHP processed products are commercially available nowadays. Guacamole, sliced ham, oysters, and fruit juices are some of the products currently available on the market. HHP technology is one of the most promising nonthermal processes.     

Characterization of amorphous granular starches prepared by high hydrostatic pressure (HHP)

Amorphous granular starches (AGS) and non-granular amorphous starches (non-AGS) of corn, tapioca and rice were prepared using high hydrostatic pressure (HHP) treatment with ethanol and water washing, respectively and their physicochemical properties were investigated. Water holding capacity and apparent viscosity of AGS and non-AGS were higher than those of native one in all starches. In RVA pasting properties, AGS and non-AGS showed higher pasting temperature and lower peak viscosity than those of native one. Furthermore, non-AGS showed distinctively lower peak viscosity compared to that of AGS possibly due to its non-granular structure. Apparent viscosity of non-AGS revealed relatively lower than commercial pre-gelatinized starch because of heat and pressure-induced gelatinization. Maintaining granular structure in HHP treated pre-gelatinized starch provide a distinctive physicochemical characteristics compared to native starch and preparation of gelatinized starch with different gelatinization and washing methods could cause big differences in their physicochemical properties.     

Safety evaluation of supercritical carbon dioxide extract of Aloe vera gel

Abstract: The gel of the Aloe vera plant has been used safely for oral and external applications. Previously, we found phytosterols derived from an extract of Aloe vera gel obtained with an organic solvent to have hypoglycemic and antiobesity effects. While developing of functional foods using Aloe vera gel, we produced an active Aloe vera gel extract (AVGE) using a supercritical carbon dioxide (CO₂) extraction procedure. In this study, we tested the safety of AVGE in vitro and in vivo. In an acute oral toxicological test in which AVGE was administered to rats at a dose of 150 mg/kg body weight, there were no deaths or apparent abnormalities at necropsy. In a 90‐d toxicity test in which rats were continuously administrered AVGE at 30 or 150 mg/kg, euthanized, and subjected to pathological examinations, no abnormalities attributable to the AVGE were found. AVGE was nonmutagenic in the Ames test and a chromosomal aberration test at concentrations of up to 5000 μg/plate and 1600 μg/plate, respectively, and in an in vivo bone marrow micronucleus test at up to 150 mg/kg/d. Practical Application: AVGE can be safely used as a functional food material.     

Hot-air drying characteristics of Aloe vera (Aloe barbadensis Miller) and influence of temperature on kinetic parameters

The aim of this research was to study and model the kinetics of the hot-air drying of Aloe vera (Aloe barbadensis Miller) and to evaluate the influence of temperature on the kinetic parameters for the proposed models. A convective dryer was used at 50, 60, 70, 80 and 90 °C with an air flow of 2.0±0.2 m/s. The sorption isotherm of the fresh product was mathematically described by the Guggenheim, Anderson and de Boer (GAB) model, giving as a result monolayer moisture of 0.20 g water/g d.b. The mathematical models evaluated in the kinetic research included five empirical equations (Newton, Henderson-Pabis, Page, modified Page and Fick's diffusional model). The fit quality of the proposed models was evaluated by using the linear regression coefficient (r²), sum square error (SSE), root mean square error (RMSE) and Chi-square statistic (χ²). The diffusivity coefficient increased with the temperature from 5.30 to 17.73×10⁻¹⁰ m²/s, for a range of temperatures between 50 and 90 °C, with an estimated activation energy of 30.37 kJ/mol. When comparing the experimental moisture values with those estimated by the proposed models, the modified Page model provided the best to fit of the data, showing that this equation correctly simulates the Aloe vera drying process and represents an excellent tool for estimating its drying time.     

Acceleration of the ageing process in mei (Prunus mume Siebold) liqueur by high hydrostatic pressure treatment

This study evaluated the effects of high hydrostatic pressure (HHP) treatment on the physicochemical composition, level of aromatic compounds and antioxidant properties of mei liqueur, as well as the microstructure of mei fruits during a 180-day ageing process. The titratable acidity, pH, and browning index of mei liqueur and HHP-treated mei liqueur did not exhibit significant differences. The HHP-treated mei liqueur displayed significantly higher ∆E, sugar and alcohol concentration during the 180-day maceration period (P ≤ 0.05). Electron microscopy revealed that HHP treatment damaged the cellular structure of mei fruits, promoting the penetration of rice wine into the fruits as well as the dissolution of aromatic and antioxidant components into rice wine, leading to the completion of the maturation of the mei liqueur. Thus, HHP technology could be used to accelerate mei liqueur maturation, shorten the time required for its ageing, exhibiting tremendous potential for applications in the liqueur industry.     

Microbiological quality of mechanically recovered poultry meat treated with high hydrostatic pressure and nisin

The combined effect of high hydrostatic pressure processing, addition of nisin and acidification on aerobic mesophilic and psychrotrophic bacterial populations of mechanically recovered poultry meat (MRPM) kept under refrigeration (2°C) was evaluated 1, 15 and 30 days after pressurization. Nisin (0, 12.055, 100 and 200 ppm) and glucono-delta-lactone (GdL; 0 and 1%) were added to MRPM. Vacuum-packaged samples were treated at 350 or 450 MPa and 2°C for 15 min using both continuous pressurization and three-cycle oscillatory pressurization for 5 min per cycle. In some samples a reduction of mesophile counts between 3.0544 and 5.0538 log cfu g⁻¹was found. Psychrotrophes seemed to be more sensitive; in samples with 100 ppm of nisin and GdL treated at 450 MPa with cycles they were reduced to undetectable levels (a lethality of approximately 7.055 log units). Cycle pressurization showed slightly better results than continuous pressurization. The combination of 350 MPa, 100 ppm of nisin and 1% of GdL was enough to extend the shelf life of MRPM during the 30 day chilled storage.