Optimization of Freeze Drying Conditions for Purified Pectinase from Mango (Mangifera indica cv. Chokanan) Peel

Response surface methodology (RSM) along with central composite design (CCD) was applied to optimize the freeze drying conditions for purified pectinase from mango (Mangifera indica cv. Chokanan) peel. The effect of pectinase content (-2.66, 62.66 mg/mL), Arabic gum (-1.21, 10.21%, w/v), and maltodextrin (0.73, 7.26%, w/v) as independent variables on activity, yield, and storage stability of freeze-dried enzyme was evaluated. Storage stability of pectinase was investigated after one week at 4 °C and yield percentage of the enzyme after encapsulation was also determined. The independent variables had the most significant (p < 0.05) effect on pectinase activity and yield of the enzyme. It was observed that the interaction effect of Arabic gum and maltodextrin improved the enzymatic properties of freeze-dried pectinase. The optimal conditions for freeze-dried pectinase from mango peel were obtained using 30 mg/mL of pectinase content, 4.5 (%, w/v) of Arabic gum, and 4 (%, w/v) of maltodextrin. Under these conditions, the maximum activity (11.12 U/mL), yield (86.4%) and storage stability (84.2%) of encapsulated pectinase were achieved.     

Potato peel extract as a natural antioxidant in chilled storage of minced horse mackerel (Trachurus trachurus): Effect on lipid and protein oxidation

The present work was undertaken to examine the utilisation of potato peel, a waste material, as a source of natural antioxidants for retarding lipid and protein oxidation in minced mackerel. Mackerel mince with two different concentrations (2.4 or 4.8 g/kg) of water or ethanol extracts of potato peel and a control with no added extracts were prepared. The samples were stored at 5 °C for 96 h and the sampling was done at time points 0, 24, 48 and 96 h. The ethanol extracts, which contained high amounts of phenolic compounds, was found to be very effective in retarding lipid and protein oxidation as it resulted in low levels of peroxide value, volatiles, carbonyl compounds and protected against the loss of α-tocopherol and tryptophan and tyrosine residues. Water extracts was less efficient especially at higher concentrations, which might be due to lower phenolic content or due to the pro-oxidative nature of some of the phenolic acids/co-extracted compounds.     

The optimisation of extraction of antioxidants from potato peel by pressurised liquids

Response Surface Methodology was used to optimise the solid–liquid extraction and Pressurised Liquid Extraction of polyphenols from industrially generated potato peel. Efficiency of extraction was optimised by measuring antioxidant activity, phenol content and the level of caffeic acid. Conditions for optimal antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were 75% ethanol, 80 °C and 22 min with solid–liquid extraction, resulting in an optimum activity of 352 mg Trolox Equivalents/100 g DW potato peel. In comparison, the use of Pressurised Liquid Extraction resulted in an optimum activity of 339 mg Trolox Equivalents/100 g DW potato peel at 70% ethanol and 125 °C. Therefore the use of Pressurised Liquid Extraction did not enhance extraction in comparison to solid–liquid extracts, but using aqueous ethanol as extraction solvent recovered a higher level of polyphenols than when using 100% methanol.     

真丝织物的核桃皮植物染料直接染色

真丝织物用植物染料核桃皮提取液染色,以K/S值为染色效果的评价指标,通过单因素试验和正交试验分析,确定了优化工艺。优化的工艺为:染液pH值2.5～3.0,染料100 mL/L,染色温度100℃,染色时间45 min。真丝织物采用该优化工艺染色,可获得较好的染色鲜艳度和较高的染色牢度,其色光偏红。     

Ultrasound-assisted extraction of polyphenols (flavanone glycosides) from orange (Citrus sinensis L.) peel

The present study reports on the extraction of polyphenols especially flavanones from orange (Citrus sinensis L.) peel by using ethanol as a food grade solvent. After a preliminary study showing that the best yield of extraction was reached for a particle size of 2 cm², a response surface methodology (RSM) was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE) followed by a central composite design (CCD) approach. The statistical analysis revealed that the optimised conditions were a temperature of 40 °C, a sonication power of 150 W and a 4:1 (v/v) ethanol:water ratio. The high total phenolic content (275.8 mg of gallic acid equivalent/100 g FW), flavanone concentrations (70.3 mg of naringin and 205.2 mg of hesperidin/100 g FW) and extraction yield (10.9 %) obtained from optimised UAE proved its efficiency when compared with the conventional method. Furthermore, the antioxidant activity determined by the DPPH and ORAC tests confirmed the suitability of UAE for the preparation of antioxidant-rich plant extracts.     

Polymethoxy flavones are responsible for the anti-inflammatory activity of citrus fruit peel

In traditional Chinese medicine, dried citrus fruit peels are widely used as remedies to alleviate some respiratory inflammatory syndromes and are considered as potential sources of anti-inflammatory components. Seven citrus fruits were selected for this study. We determined the inhibitory ability of citrus peel extracts on the production of pro-inflammatory mediators, prostaglandin E₂ (PGE₂) and nitric oxide (NO), in lipopolysaccharide (LPS)-activated RAW 264.7 cells. Among the tested citrus peels, Ponkan (Citrus reticulata Blanco) and Tonkan (Citrus tankan Hayata) deserve special attention due to their outstanding inhibitory effect on PGE₂ and NO secretion. We have also examined the composition, flavanone glycosides and polymethoxy flavones. The polymethoxy flavone content, especially nobiletin, appears to correlate well with the anti-inflammatory activities of certain citrus peel extracts. Thus, our results suggest that polymethoxy flavones contribute crucially to the anti-inflammatory activity of citrus peels.     

Clean recovery of antioxidant flavonoids from citrus peel: Optimizing an aqueous ultrasound-assisted extraction method

One of the main reasons for unsuccessful recovery of flavonoids from citrus by-products is the absence of effective extraction procedures. In this work, flavonoid fractions were obtained from citrus peels (lime, orange and tangerine) growing in South American cultivars using an optimized aqueous ultrasound-assisted extraction method with high yield (40.25 ± 12.09 mg of flavonoid fraction/g peel). Total phenolic content in flavonoid fractions obtained from different sources was 74.80 ± 1.90, 66.36 ± 0.75 and 58.68 ± 4.01 mg GAE (gallic acid equivalents)/g, for lime, orange and tangerine, respectively.The composition of flavonoid fractions was established by using HPLC/MS. Orange peel contained hesperidin, neohesperidin, diosmin, nobiletin and tangeritin, being the most complex source. Tangerine peel was the simplest source and contained only hesperidin and neohesperidin. Using the thiobarbituric acid-reactive substances (TBARS) assay it was demonstrated that all flavonoid fractions were able to inhibit cupper (Cu²⁺) or peroxynitrite (ONOO⁻) induced human low density lipoprotein (LDL) oxidation. Differences in the antioxidant activity of individual components from flavonoid fractions were also observed.     

石榴皮和石榴叶的总黄酮含量及变化研究

用分光光度法对石榴皮、石榴叶定期测量总黄酮含量,并分析其在不同时间的变化趋势。结果表明:石榴皮的总黄酮含量随时间变化而呈逐步下降趋势,在六月底石榴皮黄酮含量达到高峰值,为12.47mg/g,到九月底十月初果实成熟时,石榴皮总黄酮含量基本稳定,为6.48mg/g。石榴叶的总黄酮含量变化不大,在九月下旬有一个高峰期,达到3.04mg/g。通过组织培养的愈伤组织的总黄酮含量和石榴皮的平均水平相当,高于石榴叶的总黄酮含量。     

柚皮纤维素的提取工艺研究

以柚皮为原料,采用化学分离方法对其中纤维素的提取工艺进行了研究,以得到对重金属离子有较高吸附能力的纤维素。通过单因素实验,研究了提取过程中氢氧化钠浓度、过氧化氢浓度、脱色温度和脱色时间等工艺参数,在此基础上进行正交实验,通过极差分析确定了最佳的工艺条件,即氢氧化钠浓度为6%、过氧化氢浓度为10%、脱色时间30min和脱色温度为30℃时,柚皮纤维素含量最佳,为67.7%,对Cu2+、Pb2+的吸附容量分别为76.9mg/g与96.4mg/g,产品为乳白色粉末,带有略微柚香。     

西瓜皮营养成分分析

以西瓜皮为试材,定量分析西瓜皮中的微量元素、VC和硝酸盐含量,并研究西瓜皮中黄酮类化合物对羟基自由基的清除作用.采用火焰原子吸收光谱法对西瓜皮中Ca、Na、Mg、Fe、Cu、Zn和Mn 7种微量元素进行分析测定;利用邻二氮菲-Fe2+氧化法对西瓜皮中提取物清除羟基自由基作用的效果进行科学研究,结果表明:西瓜皮中富含对人体有益的微量元素,且VC含量较高,硝酸盐含量符合国家卫生标准.西瓜皮提取物对羟基自由基有明显的清除作用,清除率与黄酮含量呈正相关.