Thermal decomposition and oxidation of β-caryophyllene in black pepper during subcritical water extraction

Food Science and Biotechnology - Subcritical water extraction is an efficient technique for extracting components from various plants by changing the polarity of water. β-caryophyllene is a...     

Production of functional substances from black rice bran by its treatment in subcritical water

Black rice bran was treated by water and subcritical water at temperatures ranging from 20 to 260 °C for 5 min and at 200 and 260 °C for 5-120 min. The bran extracts were analyzed for their radical scavenging activity, protein and carbohydrate contents, molecular-mass distribution, antioxidation activity, emulsifying activity, and emulsion-stabilizing activity. The radical scavenging activity and the protein content of the extract were higher at higher treatment temperature. The carbohydrate content also increased with increasing temperature up to 200 °C, then steeply decreased at the temperatures higher than 200 °C. The bran extracts treated at 260 °C for 5 min exhibited a suppressive activity toward autoxidation of linoleic acid with the increasing the weight ratio of the bran extract to linoleic acid. The bran extracts prepared at 40-200 °C for 5 min showed the emulsifying- and emulsion-stabilizing activities, while the extracts prepared at 220-260 °C were low in the activities.     

Facts about the formation of new antioxidants in natural samples after subcritical water extraction

Subcritical water extraction (SWE) is a very promising technique for obtaining bioactives (mainly antioxidants) from natural sources; even if sometimes the high operation temperatures have been suggested as responsible for thermal degradation of bioactives, the fact is that this type of extraction processes may generate new bioactive (antioxidant) compounds. The present study involved the analysis of antioxidants either naturally found in raw samples and/or those formed during extraction via Maillard reaction and other chemical events. Samples of different nature like microalgae (Chlorella vulgaris), algae (Sargassum vulgare, Porphyra spp., Cystoseira abies-marina, Sargassum muticum, Undaria pinnatifida, and Halopitys incurvus) and plants (rosemary, thyme and verbena) were studied. Amino acid availability, sugar content, fluorescence and absorbance at different wavelengths were determined to follow chemical changes due to reactions such as Maillard, caramelization and thermoxidation. Folin reaction also provided information related to total phenol content of the samples. ABTS⁺, peroxyl as well as superoxide radical scavenging assays were used to measure the antioxidant capacity of the extracts. Results obtained from this study suggest that neoformed compounds derived from Maillard, caramelization and thermoxidation reactions affect the overall antioxidant capacity of water subcritical extracts depending on the nature of the sample. The brown algae U. pinnatifida was the sample in which these chemical events contributed to a higher extent to improve the antioxidant capacity (from 0.047 to 1.512 mmol/g and from 45.356 to 1522.692 μmol/g for the TEAC and ORAC_FL methods, respectively) when the extraction temperature was raised from 100 to 200 °C. To the best of our knowledge, this is the first work supporting the formation of neoantioxidants in natural complex matrices during subcritical water extraction.     

Decomposition kinetics of monoacyl glycerol and fatty acid in subcritical water under temperature-programmed heating conditions

The decompositions of monocaprylin, monocaprin, monolaurin and their corresponding fatty acids in subcritical water were measured under temperature-programmed heating conditions where the reaction temperature was linearly increased from room temperature to 350 °C at specified rates to estimate the activation energies E_i and the frequency factors k_i0 for the decompositions. The decompositions of both monoacyl glycerol and fatty acid obeyed first-order kinetics, and the decomposition of a monoacyl glycerol proceeded consecutively to form its constituent fatty acid and then further decomposition compounds. There was a tendency for both the E_i and k_i0 values for a monoacyl glycerol or fatty acid with a longer acyl chain to be smaller, and it was shown that the enthalpy–entropy compensation held for the decompositions of monoacyl glycerols and fatty acids as well as for those of fatty acid esters with various acyl and alkyl chains in subcritical water.     

Enhanced extraction of flavanones hesperidin and narirutin from Citrus unshiu peel using subcritical water

Flavanones including hesperidin and narirutin constitute the majority of the flavonoids that occur naturally in citrus fruits. The main purpose of this study was to extract valuable natural flavanones from agricultural by-products such as citrus peels using subcritical water extraction (SWE). Thus, the application of SWE to extraction of flavanones hesperidin and narirutin from Citrus unshiu peel was evaluated, and the effect of key operating conditions was determined by varying the extraction temperature (110–200 °C) and time (5–20 min) under high pressure (100 ± 10 atm). The maximum yields of hesperidin (72 ± 5 mg/g C. unshiu peel) and narirutin (11.7 ± 0.8 mg/g C. unshiu peel) were obtained at an extraction temperature of 160 °C for an extraction time of only 10 min. These yields accounted for approximately 99% of the total amount of these flavanones in the original material. The SWE was compared with three conventional extraction methods in terms of the extraction time and recovery yields for hesperidin and narirutin. The hesperidin yield by SWE was more than 1.9-, 3.2-, and 34.2-fold higher than those obtained by extraction methods using ethanol, methanol, or hot water, respectively, and the narirutin yield was more than 1.2-, 1.5-, and 3.7-fold higher.     

油炸温度对黑椒牛柳水分分布与品质相关性研究

以中式传统菜肴\     

Recovery of hesperidin and narirutin from waste Citrus unshiu peel using subcritical water extraction aided by pulsed electric field treatment

The objective of this study was to identify whether the efficacy of extracting hesperidin and narirutin from Citrus unshiu peel by-products can be increased by combining pulsed electric field (PEF) and subcritical water extraction (SWE). The samples were treated with a PEF at a strength of 3 kV/cm for 60 and 120 s. Subsequent SWE was conducted at extraction temperatures of 110–190 °C for 3–15 min. The concentration of hesperidin was highest at 46.96 ± 3.37 mg/g peel (dry basis) after PEF treatment at 120 s, combined with SWE at 150 °C for 15 min, while that of narirutin peaked at 8.76 ± 0.83 mg/g after PEF treatment at 120 s, integrated with SWE at 190 °C for 5 min. The concentrations of both hesperidin and narirutin increased with PEF treatment time. The PEF increased the amounts of hesperidin and narirutin extracted by 22.1% and 33.6%, respectively. This study demonstrate the potential of PEF pretreatment for enhancing the SWE of flavonoids from C. unshiu peel.     

Solubility and solution thermodynamic properties of quercetin and quercetin dihydrate in subcritical water

Fundamental physicochemical data is required for the design and optimization of food engineering processes, such as extraction. Flavonoids are present in natural products such as grapes and have numerous health benefits particularly with respect to their reported antioxidant properties. Such flavonoid compounds can be extracted from these natural products using a variety of solvents, among them water. In this study, the aqueous solubilities of 3,3′,4′,5,7-pentahydroxyflavone (quercetin) and its dihydrate were measured at temperatures between 25 and 140 °C using a continuous flow type apparatus. The flow rate of subcritical water was studied at 0.1, 0.2 and 0.5 mL/min to study its effect on quercetin solubility and thermal degradation at temperatures greater than 100 °C. The aqueous solubility of anhydrous quercetin varied from 0.00215 g/L at 25 °C to 0.665 g/L at 140 °C and that of quercetin dihydrate varied from 0.00263 g/L at 25 °C to 1.49 g/L at 140 °C. The aqueous solubility of quercetin dihydrate was similar to that of anhydrous quercetin until 80 °C. At temperatures above or equal to 100 °C, the aqueous solubility of quercetin dihydrate was 1.5–2.5 times higher than that of anhydrous quercetin. The aqueous solubility of quercetin anhydrate and dihydrate at different temperatures was correlated using a modified Apelblat equation. The thermodynamic properties of the solution of quercetin and its dihydrate in water were than estimated from their solubility values. A flow rate effect on the aqueous solubility of quercetin and its dihydrate was not observed until above 100 °C where higher solvent (water) flow rates (>0.1 mL/min) were required to maintain a constant solubility in the saturation cell and with minimal thermal degradation of the solute (quercetin dihydrate). The study of its particle morphology under SEM indicated an aggregation of the crystals of quercetin dihydrate at subcritical water temperatures and at lower flow rates (<0.5 mL/min), thereby inhibiting stable solubility measurements and solvent flow through the saturation cell.     

亚临界水萃取在天然产物有效成分提取中的研究新进展

本文简要阐述了亚临界水萃取技术的原理、特点和工艺,并与其他提取方式相比较,综述了亚临界水萃取技术在天然产物有效成分提取方面的研究新进展。      

Growth and survival of Salmonella in ground black pepper (Piper nigrum)

A four serovar cocktail of Salmonella was inoculated into ground black pepper (Piper nigrum) at different water activity (a_w) levels at a starting level of 4–5 log cfu/g and incubated at 25 and at 35 °C. At 35 °C and a_w of 0.9886 ± 0.0006, the generation time in ground black pepper was 31 ± 3 min with a lag time of 4 ± 1 h. Growth at 25 °C had a longer lag, but generation time was not statistically different from growth at 35 °C. The a_w threshold for growth was determined to be 0.9793 ± 0.0027 at 35 °C. To determine survival during storage conditions, ground black pepper was inoculated at approximately 8 log cfu/g and stored at 25 and 35 °C at high (97% RH) and ambient (≤40% RH) humidity. At high relative humidity, a_w increased to approximately 0.8–0.9 after approximately 20 days at both temperatures and no Salmonella was detected after 100 and 45 days at 25 and 35 °C, respectively. Under ambient humidity, populations showed an initial decrease of 3–4 log cfu/g, then remained stable for over 8 months at 25 and 35 °C. Results of this study indicate Salmonella can readily grow at permissive a_w in ground black pepper and may persist for an extended period of time under typical storage conditions.     

亚临界水萃取麦胚蛋白及其功能特性的研究

以小麦胚芽为原料,通过单因素和响应面分析实验对亚临界水萃取麦胚蛋白的工艺条件进行优化,并对其功能特性进行评价。结果表明,麦胚蛋白最佳提取条件为:萃取温度130℃,萃取时间15 min,料水比1∶20 g/m L,p H为9.4。在此条件下,麦胚蛋白的提取得率达42.25%,乳化活性为113.63 m~2/g,乳化稳定性为82.16%,起泡性为71.45%,起泡稳定性为36.05%,持水性为4.21%,持油性为4.49%,溶解度为60.93%。与传统碱溶酸沉法相比,亚临界水萃取麦胚蛋白在提取时间、提取率等方面均具有明显优势。      

亚临界水水解脱脂高温芝麻饼粕中蛋白与糖类研究

亚临界水是一种绿色化学反应介质,已经应用于农副产品加工。为拓展芝麻饼粕的利用途径,采用亚临界水将脱脂高温芝麻饼粕中的水不溶性蛋白与糖分别水解为水溶性小分子物质。以上清液中蛋白、多肽和氨基酸、还原糖浓度为指标,考察亚临界水温度、时间与pH对降解芝麻饼粕中蛋白与糖的影响。电泳结果显示亚临界水可以有效将因高温变性形成的高分子蛋白降解成低分子蛋白;亚临界水温度、加热时间与pH是芝麻蛋白和糖类水解的显著影响因素;选择适宜的亚临界水条件可以将原上清液中(0.08±0.01)mg/mL、(6.40±0.08)mg/mL、(1.2±0.1)μmol/L、(0.36±0.01)mg/mL的蛋白、多肽、氨基酸与还原糖浓度增加到(5.29±0.08)mg/mL、(22.28±0.05)mg/mL、(185.5±2.7)μmol/L和(4.28±0.12)mg/mL。     

Effects of sodium chloride on the degradation of hexoses and the hydrolysis of sucrose in subcritical water

The effects of sodium chloride on the degradation of hexoses at 220 °C and the hydrolysis of sucrose at 170 °C in subcritical water were examined. Sodium chloride accelerated the degradation at 220 °C of any hexose, especially the degradation of galactose which significantly accelerated depending on the sodium chloride concentration. On the other hand, the hydrolysis of sucrose at 170 °C was not affected by sodium chloride.     

辣椒籽精油超临界CO2萃取工艺优化及挥发性香气成分分析

为了提升辣椒籽综合利用价值,通过单因素试验和正交试验优化超临界CO₂萃取辣椒籽精油的提取工艺,并通过气相色谱-质谱(GC-MS)技术分析辣椒籽精油的挥发性香气成分。结果表明,辣椒籽精油的最佳萃取工艺为萃取压力30 MPa、萃取温度45℃、萃取时间4 h、CO₂流量30 L/h。在此优化条件下,辣椒籽精油得率可达7.04%。GC-MS检测结果表明,从辣椒籽精油中鉴定出54种化合物,包括烯烃类(16种,53.04%)、醇类(15种,29.83%)、酯类(9种,9.95%)、酮类(4种,2.5%)、酚类(2种,0.37%)、醛类(2种,0.25%)、酸类(2种,0.18%)、烷烃类(2种,0.11%)、芳香烃类(1种、0.25%)、萜类(1种,2.54%)。     

亚临界水萃取技术检测茶叶中铅、铬、镉、砷4种重金属元素残留量

目的建立以亚临界水萃取(subcritical water extraction,SCWE)及电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)检测茶叶中铅(Pb)、铬(Cr)、镉(Cd)、砷(As)4种重金属元素残留量的方法。方法待测茶叶样品在5 MPa、150℃的亚临界条件下经提取15 min后,用ICP-MS测定。结果各目标物在1~50 mg/kg范围内线性关系良好,相关系数均大于0.999。对茶叶基质进行1.0、5.0和10.0 mg/kg三个水平的加标回收实验,4种重金属元素的回收率为70.19%~113.25%,相对标准偏差RSD8.2%。结论本方法的灵敏度、准确度和精密度均符合重金属元素残留测定的技术要求,适用于茶叶中重金属元素残留的检测。     

Pressurized acidified water extraction of black carrot [<Emphasis Type="Italic">Daucus carota</Emphasis> ssp. <Emphasis Type="Italic">sativus</Emphasis> var. <Emphasis Type="Italic">atrorubens</Emphasis> Alef.] anthocyanins

The anthocyanins present in black carrot were extracted with pressurized water acidified with sulfuric, citric and lactic acids. Anthocyanin degradation became significant above 100 °C and there was no improvement when extraction pressure was increased to 100 bar. Therefore, the extraction from black carrot was carried out at temperatures 50, 75 and 100 °C under 50 bar pressure. The extraction efficiencies in terms of acylated and non-acylated anthocyanins were comparable for all three acids used to acidify water at 50 °C, while similar results were observed at 75 °C for both citric and lactic acids. Water acidified with lactic acid showed significantly higher extraction efficiency at 100 °C compared to water acidified with sulfuric and citric acids. Highest degree of polymerization together with increasing degree of browning was observed within extracts when sulfuric acid was used. On the other hand, when organic acids were used to acidify water, a higher extraction efficiency of anthocyanins, accompanied with a relatively low polymerization and browning was observed, with lactic acid giving the best results.