Combined Effect of High-Pressure and Conventional Heating on Pectin Extraction from Passion Fruit Peel

Passion fruit is one popular fruits in Brazil, and its annual production represents 70 % of the world production. About 60 % of fruit is mesocarp and epicarp (peel) and contains high levels of pectin that can be extracted using heating or alternative technologies. The purpose of the present work was to investigate the potential of high pressure to extract the pectin from passion fruit peel. The results showed that the extraction yield almost doubled (from 7.4 to 14.34 %) when high pressure was used as a pretreatment. The esterification degree and galacturonic acid of the pectin extracted were higher by 50 and 65 %, respectively. High pressure as a pretreatment was found to be an effective, time-saving, and eco-friendly method for the extraction of pectin from passion fruit peel.     

Effect of extraction conditions on the quality characteristics of pectin from passion fruit peel (Passiflora edulis f. flavicarpa L.)

Passion fruit (Passiflora edulis f. flavicarpa L.) yellow variety is composed of 50-55 g peel per 100 g of fresh fruit which is discarded as waste during processing. Utilization of passion fruit peel for pectin extraction was studied. Passion fruit peel obtained after juice extraction was blanched in boiling water for 5 min, dehydrated in a cross flow hot air drier at 60 ± 1 °C to a moisture content of 4 g/100 g of dried peel. The dehydrated passion fruit peel was used for extraction experiments of pectin. The effect of pH, peel to extractant ratio, and number of extractions, extraction time and temperature on the yield and quality characteristics of pectin were investigated. The optimized conditions for extraction of pectin from passion fruit peel yielded 14.8 g/100 g of dried peel. Pectin extracted from the dried peels had a methoxyl content of 9.6 g/100 g, galacturonic acid content of 88.2 g/100 g and jelly grade of 200. Extraction of pectin from dried peels of passion fruit may be considered for effective utilization of passion fruit processing waste.     

超声辅助柠檬酸提取百香果果皮高酯果胶及其理化性质分析

为开发优质果胶资源,利用超声辅助柠檬酸法从百香果果皮中提取高酯果胶,采用单因素实验探讨了料液比、pH、提取时间、超声功率对果胶得率的影响,应用正交试验确定果胶的最优提取工艺,并对其理化性质进行比较分析。结果表明,提取过程中各因素对果胶得率的影响大小为:提取时间 > 料液比 > pH > 超声功率;最佳提取工艺为:料液比1:40（g/mL）、pH2.00、提取时间60 min、超声功率为180 W。该条件下百香果果皮果胶得率为13.07%。经理化性质测定,果胶干燥失重为5.92%、灰分含量为4.18%、酸不溶物含量为0.27%、pH为3.55、酯化度为72.32%,属于高酯化果胶。本研究结果可为百香果果皮果胶的工业化生产提供技术支撑。     

Pectin quantity,composition and physicochemical behaviour as influenced by the purification process

To examine the purification procedure effect on the pectin amount, purity, macromolecular characteristics, and gelling ability, three pectin isolates, namely, alcohol (APP)-, dialysis (DPP)-, and metal ion (MPP)-purified pectins are obtained from acid extracts of yellow passion fruit rind using alcohol-precipitation, dialysis, or ion-binding precipitation. The results show that the amount of MPP (4.1 g/100 g) is significantly (p < 0.05) lower than the amount of the two other pectins (6.8–7.5 g/100 g). In contrast, MPP has a higher galacturonic acid (78.9 g/100 g) and lower neutral sugar (9.7 g/100 g), ash (0.9 g/100 g), and protein (1.4 g/100 g) contents than the remainder (62.4–70.1, 16.0–17.8, 2.7–5.8, 3.1–3.2 g/100 g, respectively). Molecular-weight distribution patterns suggest that MPP is free of neutral sugar oligosaccharide contaminants unlike the others, especially APP. Therefore, the term of ‘the galacturonic acid yield’ is introduced to complement the conventional term of ‘the pectin yield’. Furthermore, MPP gel preparation is likely to set more rapidly, with the gel formed achieving a much higher strength. It is concluded that the pectin amount, composition, and physicochemical properties can be considerably affected by the purification mode.     

炮制法对三叶木通果皮果胶提取及理化性质的影响

为提高三叶木通果皮果胶提取率和质量,探究不同炮制方法对三叶木通果皮果胶提取及其理化性质的影响.以未处理的三叶木通果皮生粉和炒制、砂制、醋制、酒制方法处理的果皮粉为原料,酸法提取得到果胶并进行结构表征,测定其果胶提取率、半乳糖醛酸质量分数、酯化度、乳化活性、乳化稳定性及抗氧化性.结果表明:醋制果胶提取率、半乳糖醛酸质量分...     

酸提工艺对果胶品质的影响

选用福建特产琯溪蜜柚果皮为原料,考察酸提工艺条件对果胶的酯化度、黏均分子质量和半乳糖醛酸含量的影响,设计正交试验L9(34)考察各因素的影响。结果表明:在试验范围内,酸提工艺条件对果胶的酯化度基本无影响,对半乳糖醛酸的含量有明显的影响,对果胶的分子质量影响最显著。9个不同试验条件下,酸提果胶的酯化度63.5%～63.8%,半乳糖醛酸含量74.2%～88.5%,果胶的黏均分子质量101～202ku。     

Sequential high pressure extractions applied to recover piceatannol and scirpusin B from passion fruit bagasse

Passion fruit seeds are currently discarded on the pulp processing but are known for their high piceatannol and scirpusin B contents. Using pressurized liquid extraction (PLE), these highly valuable phenolic compounds were efficiently extracted from defatted passion fruit bagasse (DPFB). PLE was performed using mixtures of ethanol and water (50 to 100% ethanol, w/w) as solvent, temperatures from 50 to 70 °C and pressure at 10 MPa. The extraction methods were compared in terms of the global yield, total phenolic content (TPC), piceatannol content and the antioxidant capacity of the extracts. The DPFB extracts were also compared with those from non-defatted passion fruit bagasse (nDPFB). Identification and quantification of piceatannol were performed using UHPLC–MS/MS. The results showed that high TPC and piceatannol content were achieved for the extracts obtained from DPFB through PLE at 70 °C and using 50 and 75% ethanol as the solvent. The best PLE conditions for TPC (70 °C, 75% ethanol) resulted in 55.237 mg GAE/g dried and defatted bagasse, whereas PLE at 70 °C and 50% ethanol achieved 18.590 mg of piceatannol/g dried and defatted bagasse, and such yields were significantly higher than those obtained using conventional extraction techniques. The antioxidant capacity assays showed high correlation with the TPC (r > 0.886) and piceatannol (r > 0.772). The passion fruit bagasse has therefore proved to be a rich source of piceatannol and PLE showed high efficiency to recover phenolic compounds from defatted passion fruit bagasse.     

Analysis of cell-wall pectin from hot and cold break tomato preparations

The initial processing of tomatoes includes a break step, which involves rapid heating of the freshly chopped tomatoes to >90 °C for hot break, or 60–77 °C for cold break. It is believed that pectolytic enzyme deactivation is the key element in the hot break step; therefore the pectin content of the different products should be qualitatively distinct. There are two general sources of pectin in a tomato fruit: the middle lamella which is rich in homogalacturonan, and the cell-wall. In this study, a 0-min or 24-min hold time (room temperature) for the chopped tomatoes preceded the break step to replicate hot and cold break, respectively, with minimum variation in the processing. The cell-wall pectin was then isolated and analyzed for the carbohydrate composition, degree of polymerization, and degree of esterification. The results showed no observable differences in pectin isolated from the two preparations, indicating that there is no significant pectolytic activity in the cell wall during the 24 min hold time; thus, the pectolytic enzymes probably act on the lower ester, middle lamella pectin in cold break products.     

Improving the pressing extraction of polyphenols of orange peel by pulsed electric fields

The influence of pulsed electric field (PEF) treatment on the extraction by pressing of total polyphenols and flavonoids (naringin and hesperin) from orange peel was investigated. A treatment time of 60 μs (20 pulses of 3 μs) achieved the highest cell disintegration index (Zp) at the different electric field strengths tested. After 30 min of pressurization at 5 bars, the total polyphenol extraction yield (TPEY) increased 20%, 129%, 153% and 159% for orange peel PEF treated at 1, 3, 5 and 7 kV/cm, respectively. A PEF treatment of 5 kV/cm to the orange peels increased the quantity of naringin and hesperidin in the extract of 100 g of orange peels from 1 to 3.1 mg/100 g of fresh weigh (fw) orange peel and from 1.3 to 4.6 mg100 g fw orange peel respectively. Compared to the untreated sample, PEF treatments of 1, 3, 5 and 7 kV/cm increased the antioxidant activity of the extract 51%, 94%, 148% and 192%, respectively.The results of this investigation demonstrate the potential of PEF as a gentle technology to improve the extraction by pressing of polyphenols from fresh orange peel. This procedure enhances the antioxidant capacity of the extracts, reduces extraction times and does not require using organic solvents.Industrial relevanceProcessing of orange fruits to obtain fresh juice or citrus-based drinks generates very large amounts of byproduct wastes, such as peels that are a rich source of polyphenols mainly flavonoids. Extraction of these compounds from orange peels is a crucial step for use of these compounds in the food and pharmaceutical industries as antioxidants. PEF-assisted extraction by pressing of polyphenols from fresh orange peels stands as an economical and environmentally friendly alternative to conventional extraction methods which require the product to be dried, use large amounts of organic solvents and need long extraction times.     

Recovery of colorants from red prickly pear peels and pulps enhanced by pulsed electric field and ultrasound

The aim of this work was to evaluate the potential of the non-conventional pre-treatments; pulsed electric fields (PEFs) and ultrasounds (USNs), to enhance the extraction of red colorants from red prickly pear (Opuntia stricta Haw.) peels and pulps. The overall goal was to valorize the thick part of the fruit, being discarded for fruit's consumption. PEF and USN treatments were first optimized using fruit slices, followed by a supplementary aqueous extraction (+ SAE) up to 1 h. The optimal conditions were then applied for peels and pulps, separately. Results showed that PEF + SAE and USN + SAE enhanced significantly the extraction of red colorants (betanin/isobetanin), compared to untreated tissues. Promising results for colorants recovery were obtained from fruit peels, using both pre-treatments, compared to that obtained from pulps, and without pre-treatment. Scanning electron microscopy revealed cell denaturation after PEF and USN pre-treatments, which can provide better recovery of the intracellular compounds with less impurity.Industrial relevanceWastes and by-products generated during fruit processing constitute a great source of high-added value compounds, which have the potential to be used as food additives and/or as nutraceuticals. Opuntia fruits constitute a great source of bioactive compounds. In particular, Opuntia fruit processing by-products are interesting as they contain a great amount of potential food additives, including food colorants (i.e. betanin/isobetanin), thus constituting an important alternative to replace synthetic colorants that have been restricted by governmental organizations. In this line, pulsed electric field and ultrasounds are proposed in this work as promising technologies for the enhancement of the extraction of colorants from red prickly pear peels and pulps.     

Characterization of pectin extracted from banana peels of different varieties

Pectins were extracted from banana peels of five different varieties using citric acid solution. The chemical characteristics of banana peel pectins were investigated and compared with citrus peel and apple pomace pectins which were extracted under the same extraction conditions to assess the potential of banana peels as an alternative source of commercial pectin. The yield of banana peel pectins ranged from 15.89 to 24.08%. The extracted banana peel pectins were categorized as high methoxyl pectin with the degree of esterification between 63.15 and 72.03% comparable to those of conventional pectin sources from citrus peel (62.83%) and apple pomace (58.44%). The anhydrouronic acid (AUA) content of banana peel pectins varied from 34.56 to 66.67%. Among various banana varieties being studied, pectin from Kluai Nam Wa variety had the highest AUA content (66.67%) which met the criteria for food additive pectin indicating its commercial significance as an alternative pectin source.     

干燥方法对柠檬果胶理化性质影响

为探究不同干燥方法对柠檬果胶理化性质的影响,实验以柠檬干渣为原料制备果胶,固定提取和浓缩条件,采用热风干燥、真空干燥、冷冻干燥及喷雾干燥等干燥方法对柠檬果胶进行干燥处理,研究不同干燥方法对柠檬果胶得率、半乳糖醛酸、酯化度、能耗、复水比、凝胶强度及果胶结构的影响,采用变异系数法对各指标加权评分,确定柠檬果胶最佳干燥方法。结果表明:所有干燥后的果胶半乳糖醛酸含量均达到国标65%的要求;酯化度均大于50%,傅立叶红外光谱(Fourier Transform Infrared Spectrometry,FTIR)显示,不同干燥方法干燥后的果胶均具有果胶的特征官能团,说明所用干燥方法不会对果胶结构产生影响。不同干燥方法干燥后的果胶各指标均存在显著性差异(P<0.05),加权综合评分最高的方法是:60℃真空干燥,所得柠檬果胶得率、半乳糖醛酸、酯化度、单位能耗、复水比、凝胶强度分别为17.84%、82.44%、73.16%、28.13 kJ/g、5.36%、149.71 g。真空干燥所需设备简单,且能耗相对较低、产品品质好,对柠檬果胶制备研究具有重要意义。     

制备方法对山楂果胶理化特性的影响

山楂果胶作为一种纯天然的食品添加剂,在食品生产和加工中起着重要作用。本实验采用热风干燥和冷冻干燥两种不同的干燥方法以及研磨、剪切、气流3 种不同的粉碎方法来处理山楂,得到6 种山楂粉,进而对山楂粉热特性进行分析,并以山楂粉为原料进行山楂果胶的提取,同时通过半乳糖醛酸质量分数、总糖质量分数、酯化度测定和傅里叶变换红外光谱、X射线衍射、流变学分析对不同方法制备的山楂果胶理化特性进行比较。结果表明：不同处理条件的山楂粉热特性并未表现出明显差异,冷冻干燥组果胶得率和半乳糖醛酸质量分数均高于热风干燥组。同种干燥方法不同粉碎方法对山楂果胶的理化性质影响总体差异不显著（P＞0.05）,同种粉碎方法不同干燥方法处理下,冷冻干燥组的各项理化性质显著优于热风干燥组（P＜0.05）。本实验可为实际生产山楂果胶产品提供理论参考。     

不同部位柚子果胶提取率与理化特性相关性研究

采用酸处理乙醇沉淀法从柚子黄皮、白皮、囊衣、果肉中提取果胶,计算提取率,对提取的柚子果胶进行pH、半乳糖醛酸、酯化度、溶解度、黏度等理化特性的测定,并分析果胶液的热稳定性、提取率与理化特性的相关性。结果表明,柚子不同部位果胶的提取率表现为：果肉>白皮>囊衣>黄皮,pH为：黄皮>囊衣>白皮>果肉,半乳糖醛酸含量：白皮>黄皮>囊衣>果肉,酯化度：囊衣>白皮>果肉>黄皮,溶解度：果肉>白皮>囊衣>黄皮;各部位提取率、半乳糖醛酸、酯化度均存在极显著差异（p <0.01）,黄皮、囊衣、白皮果胶之间pH差异不显著（p> 0.05）;柚子果胶提取率与pH呈显著负相关（r=-0.973,p<0.05）;柚子各部位果胶的黏度均优于市售果胶,但高温降低了柚子果胶的热稳定性。     

Cloud stability of apple juices in relation to their particle charge properties studied by electro-optics

Turbidity, cloud stability, pulp and pectin contents, and particle charge properties of apple juices were studied depending on the normal atmosphere cold storage of four apple cultivars. Cloud stability and adsorbed pectin content increased after the cold storage, while coarse/fine pulp ratio decreased. The rise of stability was correlated well (R = 0.92) with the increase of particle electric polarizability determined by electric light scattering. The latter effect is probably due to the enhanced amount and reduced degree of esterification of the adsorbed pectin. The results of the present study clearly demonstrate the advantage of the electro-optics for elucidation of the cloud stability mechanism. Moreover, the processing of apples after their cold storage is shown to be worthwhile, allowing an improvement of cloud stability.     

响应面法优化籽瓜皮中高纯度果胶的提取工艺

利用响应面法优化籽瓜皮中高纯度果胶的提取工艺条件,以半乳糖醛酸的含量为果胶纯度的评价指标,采用咔唑-硫酸比色法测定果胶中半乳糖醛酸含量。在单因素试验的基础上,选择提取温度、提取时间和提取液pH值等因素进行响应面试验设计。结果表明,果胶提取最佳工艺条件为提取时间150 min、提取温度88 ℃、提取液pH值为1.6、料液比为23∶1(g∶L)。优化工艺所提取果胶中半乳糖醛酸含量理论值为78.03%,实测值为76.65%,实际测定值与理论计算值基本吻合。     

Rheology,spontaneous whey separation,microstructure and sensorial characteristics of probiotic yoghurts enriched with passion fruit fiber

Beyond demonstrated beneficial health attributes, passion fruit rinds are a by-product of the fruit pulp industry, rich in total dietary fiber, particularly pectin. The aim of this study was to evaluate the influence of the addition of passion fruit fiber on the whey formation, rheological parameters, microstructure and sensorial characteristics of probiotic yoghurts. Skim milk bases enriched with 1% of passion fruit fiber or not were heat treated and inoculated with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and divided into four groups according to the probiotic strain added — Lactobacillus acidophilus strains L10 and NCFM and Bifidobacterium animalis subsp. lactis strains Bl04 and B94. Fermentations were performed until the pH reached 4.5. Rheological characteristics of yoghurts were determined by a rotational rheometer in two cycles of shear rate ranging from 0 to 15 s^? 1 in both upward and downward curves. Sensorial analysis of passion fruit fiber yoghurts, either without any probiotic or co-fermented by L. acidophilus L10 or B. animalis subsp. lactis Bl04, was evaluated against a control yoghurt without fiber. Photomicrographs of freeze-dried yoghurts were made by field-emission scanning electron microscope (SEM). Thixotropy of enriched yoghurts was higher than that of their respective controls in the two cycles of shear rate. Apparent viscosity was significantly higher in fiber yoghurts co-fermented by the lactobacilli than in their controls at the end of cold storage. Photomicrographs demonstrated that in passion fruit fiber yoghurts the casein gel was more compact and overlaid the fiber, while filaments of exopolysaccharides were more frequent in control yoghurts. Appearance, odor and color of the passion fruit fiber yoghurts received scores as ‘good’, and the intensity of the passion fruit flavor was considered weak by the sensory assessors. Results indicate that the passion fruit fiber is an almost neutral ingredient for the design of new high value-added yoghurt.     

Pasteurization of citrus juices with ohmic heating to preserve the carotenoid profile

This study was carried out to assess, for the first time, the effect of ohmic heating on the carotenoid profile of two citrus fruit juices: grapefruit and blood orange. Two heat treatments were designed to obtain pasteurization values of 50 and 150 min (Tref = 70 °C and z-value = 10 °C) with ohmic heating as compared to conventional heating. The results showed that xanthophyll losses could reach 70% for epoxyxanthophylls (cis-violaxanthin and cis-antheraxanthin) and 40% for hydroxyxanthophylls (β-cryptoxanthin, lutein, and zeaxanthin) with conventional heating, but losses were under 30% and 20%, respectively, with ohmic heating. Carotene species (lycopene and β-carotene) were stable regardless of the treatment. No negative non-thermal effects of ohmic heating were shown on carotenoids. Loss simulations of the studied carotenoids showed that the high temperatures reached with ohmic heating during pasteurization could substantially increase the organoleptic and nutritional quality of acid carotenoid-rich juices.Industrial relevanceCitrus are the top fruit crops in terms of world trade. This craze for them -particularly orange and grapefruit- is notably due to their high content in organoleptic and nutritional compounds of interest and among them carotenoids. About 50% of the Citrus production is processed in juice. From the growing variety of products, minimal processed juices now have a significant market share. This work assessed for the first time the effect of ohmic heating, a thermal method for stabilizing juices while minimizing the impact on the juice quality, on the carotenoid profiles of blood orange and grapefruit juice. Pasteurization with ohmic heating was proven to be a very good alternative for protecting carotenoids and especially xanthophylls compared to conventional heating. These results will help in designing ohmic heating process parameters for optimizing the overall quality of carotenoid-rich fruit juices.     

The potential of ohmic heating as an alternative to steam for heat processing shrimps

The potential application of Ohmic Heating as an alternative to the conventional steam cooking for shrimps is examined in this study. Defrosted unpeeled shrimps (Pandalus borealis) were cooked either in a steamer or ohmically up to a 72 °C core-temperature. The head, body and tail of steam-heated shrimps cooked at different rates whereas the OH treatment was more uniform and faster. The impact of shrimp size on heating rate was also evaluated, with an overall cooking time of 38 s and 59 s for steam-cooked small and large shrimps, respectively, while only 40 s where needed for OH regardless of shrimp size and measured anatomical location. No differences were found for cook loss and texture (WBSF and Kramer methods) between cooking methods. However, shrimp size seemed to determine the effect of OH on colour differences (ΔE), with greater differences observed in large vs. small shrimps, although overall ohmically-cooked shrimps showed less colour differences compared to those cooked conventionally with steam.Industrial relevanceTraditional heating processes such as boiling or steaming are used in industrial cooking of shrimps. However, the low rate of heat penetration to the thermal centre of shrimps leads to heterogeneous treatments resulting in overcooking which may reduce yield. Ohmic heating technology offers a potential alternative over conventional heat treatments as heat is generated volumetrically inside the food. This form of heat generation results in more uniform temperature distribution which leads to shorter processing times and potentially higher yields while still maintaining the colour and nutritional value of food. This paper hence exploits the potential of Ohmic heating technology as an alternative to conventional steam processing for the cooking of shrimps.     

百香果皮果胶提取工艺及其对面团和面包品质的影响

从百香果皮中提取果胶作为面包改良剂,以未添加改良剂和添加豆渣的面团为对比,通过质构仪分析百香果皮果胶对生面团延展性和面包坚韧性的影响。结果显示:百香果皮果胶提取的最佳工艺条件为:质量分数为0.45%的草酸铵、料液比1∶45(g/mL)、50 W超声波辅助提取90 min,果胶提取率为24.79%。质构测试结果表明:添加百香果皮果胶的面团拉丝长度、弹性、粘性和内聚性较大,而硬度较小,其面团品质最好。添加豆渣和百香果皮果胶均使面包的硬度和咀嚼性降低,有效改善面包的质构特性。Kramer感官评定结果表明百香果皮果胶面包最受消费者喜爱。