銅藻膳食纖維提取條件的優(yōu)化的綜述

1、附錄一.文獻(xiàn)綜述銅藻膳食纖維的應(yīng)用及發(fā)展現(xiàn)狀摘要 銅藻作為褐藻的一種，在我國沿海地區(qū)有著廣泛的分布，資源豐富，民間可全藻用藥,多作為制膠工業(yè)原料，但其化學(xué)成分特別是有生物活性的特效成分研究得較少，已見報(bào)道含褐藻酸，甘露醇，多糖等成分。膳食纖維是人類消化過程所需要的一類重要的食物營養(yǎng)素，對人類的健康有著重要作用1。本文主要介紹膳食纖維的分類、分離提取、在食品中的應(yīng)用、研究現(xiàn)狀及發(fā)展趨勢。關(guān)鍵詞 膳食纖維；銅藻；應(yīng)用Abstract To be one kind of the brown algae, Sargassum Horneri widely distributes in Coastal

2、area in our country.Being rich in the resources,it can be used in medicine and be treated as material for industry.But its chemical composition, particularly characteristic components that have biological activity have been studied lesser.It has been reported that it included algin, mannitol and amy

3、lose.Dietary fiber is a kind of food nutriment in digestion.It has important effect in healthiness of human being.In this paper,it mostly introduced the classification, The separation withdraws,the application in food, the study actuality and the development tendency.Key Words Dietary fiber;Sargassu

4、m Horneri;Application銅藻產(chǎn)于嵊山、中街山、漁山、韭山、大陳和南麂。我國沿海都有分布。本種系北太平洋西部特有的暖溫帶性海藻。可作。 藻體黃褐色，樹狀，枝葉繁茂，高0.5l米，可達(dá)7米。主枝圓柱形，下部有數(shù)條縱走淺溝，直徑1.53毫米。互生、對生分枝，吟片披針形，中肋及頂，鋸齒深裂。柄細(xì)長。氣囊圓柱形，長0.5l厘米，直徑23毫米，兩端尖細(xì)，冠吟羽裂， 中肋及頂，固著器裂瓣?duì)?。生殖托圓柱形，有短柄，雄托長48厘米，直徑1.52毫米；雌托長1.53厘米，直徑23毫米。生長在風(fēng)浪較大的干潮線以下至3米處的巖石上或低潮帶石沼中。生長盛期35月。膳食纖維是人類消化過程所需要的一類重要

5、的食物營養(yǎng)素2。大量研究表明，膳食纖維在結(jié)腸癌、高膽固醇血癥、冠心病、肥胖、糖尿病以及其它多種慢性疾病防止中具有積極作用。隨著現(xiàn)代科學(xué)技術(shù)在醫(yī)學(xué)、生物學(xué)等領(lǐng)域取得的突破性成就，近年來國際營養(yǎng)學(xué)家一致認(rèn)為膳食纖維能夠平衡人體營養(yǎng)，調(diào)節(jié)機(jī)體功能，可與傳統(tǒng)的6大營養(yǎng)素（即蛋白質(zhì)、脂肪、水、礦物質(zhì)、維生素、碳化物）并列為第七大營養(yǎng)素3。我國居民以植物性食物為主，膳食纖維的攝入相對充足。但近年來，人們的膳食結(jié)構(gòu)發(fā)生了很大變化，慢性病的患病率也在不斷上升。1 膳食纖維的性質(zhì)及分類膳食纖維按其溶解性，可分為水溶性膳食纖維(soluble dietary fiber, SDF)和水不溶性膳食纖維(insolu

6、ble dietary fiber ,IDF) 4。水溶性膳食纖維主要指細(xì)胞壁內(nèi)的儲存物質(zhì)和分泌物，如果膠、樹膠、葡聚糖、瓜兒豆膠、梭甲基纖維素等;水不溶性膳食纖維主要指細(xì)胞壁的組成部分，如纖維素、半纖維素、木質(zhì)素、殼聚糖和植物蠟等。按膳食纖維的來源分，可分成植物來源膳食纖維、動物來源膳食纖維、海藻多糖類膳食纖維、微生物多糖、合成半合成類膳食纖維等5。2 膳食纖維的分離提取膳食纖維依據(jù)原料和對膳食纖維產(chǎn)品特性要求的不同，分離提取方法有很大不同，必須的幾道工序包括原料粉碎、浸泡沖洗、漂白脫色、脫水干燥和產(chǎn)品粉碎過篩等。2.1 化學(xué)法 采用化學(xué)法提取膳食纖維，以堿法提取應(yīng)用較普遍，如在提取過程中改

7、變堿液濃度，并輔以其它化學(xué)試劑，還可將水溶性或非水溶性膳食纖維進(jìn)一步分離。除堿法提取外，還有酸法、絮凝劑法等。其原理是利用化學(xué)試劑除去原料中的蛋白質(zhì)、淀粉、脂肪等成分，從而分離提取膳食纖維。2.2 酶法 加人各種酶類分解原料中的蛋白質(zhì)、淀粉、脂肪等成分，從而分離提取膳食纖維。若在所得的膳食纖維中再引人半纖維素酶、阿拉伯聚糖酶等，可制備一些活性成分，從而提高膳食纖維品質(zhì)。2.3 膜分離法 膜分離法制備膳食纖維的報(bào)道不多，由于該法能通過改變膜的分子截留量制備不同分子量的膳食纖維，且能實(shí)現(xiàn)工業(yè)化生產(chǎn)，可以預(yù)見，它將是分離水溶性膳食纖維最有前途的方法。2.4 化學(xué)試劑和酶結(jié)合分離法采用化學(xué)分離法制備的

8、膳食纖維還含有少量蛋白質(zhì)和淀粉，要制備極純凈的膳食纖維，必須結(jié)合酶處理，利用酶降解膳食纖維中殘存的蛋白質(zhì)和淀粉等雜質(zhì)5。3 膳食纖維的應(yīng)用膳食纖維食品在西方國家的風(fēng)行始于20 世紀(jì)70年代， 日本對膳食纖維的興趣起源于 20世紀(jì) 90年代，我國食品行業(yè)到20世紀(jì)90 年代末才開始有強(qiáng)化膳食纖維食品問世?，F(xiàn)在，膳食纖維的獨(dú)特生理功能和營養(yǎng)保健作用使其作為主要食品組分在食品中得到了廣泛的應(yīng)用，與維生素和礦物質(zhì)處于同等的地位。3.1 在主食食品中的應(yīng)用膳食纖維可用于制作饅頭、掛面、方便面等主食。 饅頭中加入6%的膳食纖維，成品顏色及味道如同全麥粉做成的饅頭，并且有特殊的香味， 口感良好。面條中加入5

9、%的膳食纖維，面條熟后強(qiáng)度增加、韌性良好、耐煮耐泡，口感清爽。 也可把膳食纖維添加到谷物原料中， 通過適當(dāng)?shù)募庸すに囎龀稍绮褪称贰?.2 在焙烤食品中的應(yīng)用膳食纖維在焙烤食品中得到了廣泛的應(yīng)用，典型產(chǎn)品有：高膳食纖維面包、蛋糕、餅干等。膳食纖維在焙烤食品中的添加，能改變制品的質(zhì)構(gòu)，提高其持水力，增加其柔軟度和疏松度，延長制品的貨架期。膳食纖維在焙烤食品中的添加量宜控制在5%-6%，添加量不宜過大，否則會影響制品的質(zhì)地和口感。 比如，在糕點(diǎn)制作中含有大量的水分， 烘焙時會凝固成松軟的產(chǎn)品而影響質(zhì)量， 膳食纖維的添加可保持糕點(diǎn)制品的綿軟、滋潤，增加其保質(zhì)期。3.3 在乳制品中的應(yīng)用乳制品被認(rèn)為是含

10、有除膳食纖維外人體所需的全部營養(yǎng)素，一杯牛奶能強(qiáng)壯一個民族，到2001年底我國人均乳制品消費(fèi)已接近10kg/年。在乳制品中添加膳食纖維能同時滿足人們對蛋白質(zhì)、 維生素A脂肪等動物性營養(yǎng)成分和膳食纖維等植物性營養(yǎng)成分的需求， 能進(jìn)一步提高乳制品的營養(yǎng)價值和應(yīng)用范圍。長期飲用添加膳食纖維的乳制品能使腸道舒暢，防治便秘，并可降低膽固醇、調(diào)節(jié)血脂、血糖、協(xié)助減肥，尤其適合中老年人、糖尿病人、肥胖者飲用。 在液態(tài)乳品中的建議添加量為 1%-5%；在固態(tài)乳品中的建議添加量為1%-3%。3.4 在飲料制品中的應(yīng)用 膳食纖維飲料是西方國家很流行的功能性飲料，它既能解渴、補(bǔ)充水分，又可提供人體所需的膳食纖維。這

11、類產(chǎn)品，尤其是水溶性膳食纖維在歐美和日本比較流行。我國的膳食纖維飲料種類繁多，主要用于液體、固體和碳酸飲料，也有將膳食纖維用乳酸桿菌發(fā)酵后制成乳清型飲料。水溶性膳食纖維在果汁、果肉混濁類飲料中的建議添加量為0.5%-1.5%在透明類飲品中的建議添加量為 0.3%-1.2%。3.5 在肉制品中的應(yīng)用 對肉制品行業(yè)而言，隨著瘦肉型豬的普及，充分利用肥肉已不是迫切需要解決的問題， 但是日益關(guān)注健康的消費(fèi)者對食物提出了更高的要求， 即高蛋白、低脂肪，但降低脂肪會嚴(yán)重影響肉制品的風(fēng)味和口感， 解決這一問題的途徑之一就是脂肪代用品的使用。脂肪代用品主要有三大類：蛋白質(zhì)類、淀粉類、膳食纖維類。蛋白質(zhì)類主要用

12、于冷凍食品；淀粉類具有良好的吸水作用，并具有一定的黏度，而且價格低廉，因而為多數(shù)企業(yè)所使用，但淀粉用量增多后，產(chǎn)品的粉質(zhì)感較重，導(dǎo)致產(chǎn)品的品質(zhì)下降；膳食纖維類是一些高分子聚合物，不易為人體所消化和吸收，它具有良好的保水、保油和凝膠性能，并會使產(chǎn)品具有豐厚、潤滑的口感，從而達(dá)到模擬脂肪的感官特征。比如在火腿腸中添加2.53的膳食纖維， 可提高產(chǎn)品的出品率，增強(qiáng)其口感和質(zhì)構(gòu)。3.6 在其它食品中的應(yīng)用 除上述應(yīng)用外，膳食纖維還可用于快餐、膨化食品、糖果、肉類、罐頭和一些功能性保健食品中，它同樣可起到相同的生物功效6。4 膳食纖維的研究現(xiàn)狀及發(fā)展趨勢4.1研究現(xiàn)狀膳食纖維資源豐富，價格低廉，因此有著

13、廣泛的應(yīng)用前景， 國外膳食纖維食品的開發(fā)應(yīng)用已經(jīng)較為普遍，而我國對于膳食纖維的研究與開發(fā)與國外還是有一定的差距，應(yīng)用研究也處在起步階段。因此在我國還有待統(tǒng)一規(guī)劃，有計(jì)劃地協(xié)調(diào)全國力量，確定重點(diǎn)開發(fā)資源，協(xié)作攻關(guān)，早日在我國形成膳食纖維多品種生產(chǎn)的龍頭產(chǎn)業(yè)，以滿足廣大食品市場的需要，優(yōu)化和改善我國人民膳食結(jié)構(gòu)7 ?？梢钥隙ǖ氖牵瑢ι攀忱w維所具有的生理功效進(jìn)行研究和應(yīng)用，一定具有較好的社會效益和經(jīng)濟(jì)效益，并且在經(jīng)濟(jì)發(fā)展的同時，減少相關(guān)疾病的發(fā)生，保證人民身體健康8。4.2 發(fā)展趨勢膳食纖維研究的發(fā)展趨勢主要體現(xiàn)在以下幾點(diǎn)： 膳食纖維資源的開發(fā)，一方面是對現(xiàn)有的資源(如米糠、麥麩、豆渣、蘋果渣等)的

14、進(jìn)一步利用，另一方面是對未發(fā)掘的資源進(jìn)行調(diào)查與開發(fā)； 膳食纖維分離制備方法的研究，由于不同的加工方法對膳食纖維產(chǎn)品的理化性質(zhì)和生理功能有明顯影響，如反復(fù)用水浸泡沖洗和頻繁的熱處理會明顯減少膳食纖維終產(chǎn)品的持水力和膨脹力，這樣不僅會惡化其工藝特性，而且會影響其生理功能的發(fā)揮。因此，采用較為溫和的工藝方法和高新技術(shù)提取分離膳食纖維是今后膳食纖維的研究方向之一； 膳食纖維的生理功能的研究，關(guān)于膳食纖維的生理功能已有不少報(bào)道，但是膳食纖維的抗氧化作用和清除自由基的活性作用是否能進(jìn)入血液循環(huán)對人體生理過程產(chǎn)生影響，膳食纖維的解毒機(jī)理，膳食纖維中單糖與醛酸與由它們構(gòu)成的膳食纖維生理功能之間確定的關(guān)系以及膳

15、食纖維其它一些理化特性與人體的生理關(guān)系等等方面都值得進(jìn)一步研究； 膳食纖維用途進(jìn)一步的拓展，膳食纖維的各種獨(dú)特理化性質(zhì)、生理功能以及作為環(huán)保材料的種種優(yōu)點(diǎn)的確有許多可開發(fā)的用途值得進(jìn)一步去探索； 膳食纖維的工業(yè)化生產(chǎn)的研究，如何將膳食纖維這一長期被忽視的寶貴資源充分利用起來，不僅要求其應(yīng)用范圍的拓寬，更要求將膳食纖維產(chǎn)品以工業(yè)化規(guī)模開發(fā)出來，使之有經(jīng)濟(jì)上的可行性，提高膳食纖維的開發(fā)利用的經(jīng)濟(jì)價值，也是研究方向之一。參考文獻(xiàn)1 袁清香，付玲.銅藻Sargassu Horneri的化學(xué)成分研究J.廣東化工，2006,33(5):42-432 陳培基，李劉冬，楊賢慶等. 酶處理馬尾藻提取膳食纖維的研

16、究J. 食品與發(fā)酵工業(yè)， 2003，29(12):76-793 粱永江.膳食纖維與人類健康關(guān)系的研究進(jìn)展J.中華臨床醫(yī)藥,2004,5(5):43-454 劉曉婷.膳食纖維的開發(fā)及應(yīng)用J.中國食物與營養(yǎng),2004,(9):21-245 曾順德，張迎君，漆巨容.膳食纖維開發(fā)利用現(xiàn)狀J.西南園藝，2005,33:99-1016 陸勤豐.膳食纖維制品的開發(fā)研究J.糧食加工，2005,(4)：44-477 劉成梅，李資玲，梁瑞紅等. 膳食纖維的生理功能與應(yīng)用現(xiàn)狀J. 食品研究與開發(fā)，2006，33（1）：122-1258 修建成,曹榮安 ,孫保華等. 膳食纖維的生理功能與應(yīng)用現(xiàn)狀J，農(nóng)產(chǎn)品加工,200

17、5,(8):48-539 Nuria Grigelmo-Miguel ，Olga MartõÂ n-Belloso*.Characterization of dietary fiber from orange juice extraction. Food Research International,1999,(31) 5: 355-361 10 S.H. Knutsen a,*, A.K. Holtekjolen a,b. Preparation and analysis of dietary fibre constituents in whole grain from

18、hulled and hull-less barley. Food Chemistry ,2007,(102):707-715附錄二.外文文獻(xiàn)原文一Characterization of dietary fiber from orangejuice extractionNuria Grigelmo-Miguel & Olga MartõÂ n-Belloso*Food Technology Department, UTPV-CeRTA, University of Lleida, Rovira Roure 177, 25198 Lleida, SpainResidu

19、es from orange juice extraction are potentially an excellent source of dietary fiber (DF), because this material is rich in pectin and may be available in large quantities. Chemical and physical characteristics of DF obtained from orange pulp were determined for three varieties of oranges. Total DF

20、content reached quite high values: 35.4±36.9% dry matter (DM). Orange DF was rich in pectins (15.7±16.3% DM), as well as cellulose and hemicellulose (16.6±18.1% DM) and lignin (2.2±3.0% DM). The product showed a relatively high water holding capacity (7.3±10.3 g water/g fibe

21、r), high oil absorption property (0.9±1.3 g oil/g ®ber) and ow caloric value(3519±3735 cal/g). Chemical analyses of orange DF concentrate howed low contents of protein, fat and ash (8.1±10.1%, 1.5±3.0% and 2.6-3.1% DM, respectively). The orange DF color ranged from yellow to

22、 light orange. These characteristics suggested many potential applications such as, clouding agent in beverages, thickener and gelling agent as well as binder, texturizer and low calorie bulk ingredient. # 1999 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All

23、 rights reservedKeywords: by-products, orange, dietary fiber, pectin.INTRODUCTIONThe availability of high quality foods with a high dietary fiber (DF) content is of key importance in obtaining changes in fiber intake recommended for adults in western societies. High dietary fiber intake is indicated

24、 in the treatment and prevention of many diseases including colon cancer, coronary heart disease, obesity, diabetes and gastrointestinal disorders (Anderson et al.,1994). The usual sources of DF in fiber-enriched foods are cereals but the use of fruits as a source of DF could be more physiologically

25、 adequate (Saura-Calixto, 1993) and quite feasible.The world production of citrus fruits was nearly 58 million metric tons in the 1993±1994 growing season, with oranges accounting for 75% of the total (Florida Department of Agriculture, 1995). Two major producers, Brazil and the United States,

26、grow 60% of the world's oranges and 85% of their production is processed as juice. Mediterranean countries are quickly becoming both producers and processors (Johnson, 1994).When orange juice extraction is completed, the amount of rejected bagasse is almost equal to that of juice. This refuse is

27、 treated as waste and discarded or used as raw materials for vinegar, molasses and feedyeast (Braddock, 1995), but these are limited applications. By-products from orange juice extraction have apotential use as a DF source. The material is rich in pectin and, in addition, plentiful and inexpensive.T

28、here is an increasing interest in pectins for their potential to bring down blood cholesterol levels, specifically, by decreasing the low-density-lipoprotein-cho-lesterol fraction without changing the levels of high-density-lipoprotein-cholesterol and triglycerides. Pectins also a.ect glucose metabo

29、lism by lowering the glucose response curve (Ink and Hurt, 1987; Reiser, 1987; Baker,1994). Besides clinical applications, pectin is used as a food additive because of its specific properties as a gelling agent (Sanderson, 1981; Pilnik and Voragen, 1992). Given that DF concentrates from oranges may

30、be used as an ingredient in food formulations, it is necessary to evaluate orange DF components and properties.The objectives of this study were to determine the DF content and the main constituents of orange DF concentrates obtained from the juice extraction residue. Three orange varieties were con

31、sidered: Navel, Salustiana and Valencia Late. The proximate composition of orange DF and the most important physical and chemical properties (pH, acidity, color, apparent density, energy value, and water and oil holding capacities) were also evaluated.MATERIALS AND METHODSSample preparationThe DF co

32、ncentrates from orange (Citrus sinensis) vars. Navel, Salustiana and Valencia Late were supplied by the factory Indule rida, S.A. (Alguaire, Lleida, Spain). The ripeness indexes (RI = soluble solids/titrable acidity, citric acid) of the original oranges were Navel=12±14; Salustiana=8±

33、;11; Valencia Late=12±15 (data from the supplier). The orange DF concentrates were obtained from orange bagasse, which remained after orange juice extraction. The bagasse was collected from a juice extractor (291-B model, FMC Corporation, Citrus Machinery Division, Lakeland, FL). The juice extr

34、actor discharged the rind, and the inner part of the fruit was pressed in the central extraction tube. All orange rind was discarded. After the oranges were thoroughly squeezed, the juice and the bagasse were passed through a prefinisher in the central extraction tube and,finally, through a fine scr

35、een in the finisher to separate juice from bagasse. The bagasse consisted of the central core, the segment membrane and the pulp. This bagasse was washed and dried according to factory protocol (Sorribas, 1993), to obtain orange DF concentrate.Upon arrival to our laboratory, the orange DF concentrat

36、es were grounded to 30 mesh with a centrifugal milling (Cyclotec 1093, Tecator, HoÈ ganaÈ s, Sweden) prior to physical and chemical determinations.Fiber analysisEnzymatic removal of protein from orange DF concentrates and separation into soluble and insoluble fractions by centrifugation wa

37、s carried out according to ManÄ as (1992), a modification of the AOAC method (Prosky et al., 1988) (Fig. 1). The entire treatment was carried out in a centrifugation tube, avoiding any possible sample loss. Samples were enzymatically digested under the conditions specified in the AOAC ocial met

38、hod (Prosky et al., 1988). Given that the samples did not contain starch, -amylase and amyloglucosidase treatments were not necessary. After performing the protease treatment, insoluble DF residue was obtained through a centrifugation step (1000 g). Supernatant and water washes were collected in the

39、 same tube for further isolation of the soluble DF fraction, which was dialyzed using a continuous water-renovation system. The system consisted of a 30 l methacrylate dialysis chamber linked to a pre-chamber, with a thermostat and an evaxcuation system. Tap water was propelled with a peristaltic pu

40、mp to the bottom of the pre-chamber, where it was heated to 25, overflowing then into the dialysis chamber. Waterflow was 7 l/h. Soluble DF fractions were introduced into dialysis tubing (12 000±14 000 MWCO, Dialysis Tubing Visking 9-36/32 mm, Medicell International, Ltd., London, UK) and place

41、d into the dialysis chamber. An additional device that created an elliptical movement, attached to a speed control system achieved continuous agitation of the dialysis bags. Neutral Sugars and Uronic Acids in the soluble DF fraction were quantified by spectrophotometric procedures (Southgate, 1976;

42、Scott, 1979,respectively).pH and acidityThe pH was determined potentiometrically with a pH meter using 10% (w/v) orange DF solutions. The acidity of these solutions was determined by titration with NaOH 0.1 N to pH 8.10. Results were expressed in g acid citric/100 ml of sample.Color determinationThe

43、 cieLab coordinates (L*, a*, b*) of the orange DF concentrates were directly read in a glass cuvette with a spectrophotocolorimeter MiniScan MS/Y-2500 (Hun-terLab, In., Reston, VA, USA), calibrated with a white tile (L*=94.0, a*=ÿ1.1, b*=0.6), at 60_ with a D-65 illuminant source.Apparent densi

44、tyThis was determined as the weight divided by the volume of the orange DF concentrate (Larrauri et al., 1994).Energy valueThe energy value was determined by combustion with the aid of a calorimetric pump (Autobomb,Gallenkamp, UK).Water (WHC) and oil (OHC) holding capacity determinationThe WHC and O

45、HC of the orange DF concentrates were determined at 25 by centrifugation according to the Chevalier (1993) method.Complementary analysisProtein, ash, fat and moisture determinations of orange DF were carried out by standard procedures (AOAC, 1997).Statistical analysisThree measurements were taken on

46、 each analysis, and the results were expressed as the mean of those values.standard deviation. Analysis of variance procedure (Statgraphics, 1993) was performed at p > 0.05 to study the variation among orange varieties. The Least Significant Difference (LSD) test was employed todetermine di.erenc

47、es among results.RESULTS AND DISCUSSIONDietary fiber contentInsoluble, soluble and total DF contents of orange DF concentrates are shown in Table 1. The insoluble DFwas the major fraction in orange DF concentrates, but a high soluble DF fraction content was obtained (11.3±13.0% DM). The high pr

48、esence of both fractions in orange DF concentrates indicates a DF with very good physiological e.ects, better than cereals which have a very low soluble DF proportion (0.40±3.17% DM) (Table 2). Insoluble DF is important to intestinal regulation, whereas the soluble fraction is involved in reduc

49、tion of both blood cholesterol and intestinal glucose absorption (Periago et al., 1993). Soluble DF was 30.6±36.2% of total DF content. This is a relatively high value in comparison with other fruit and vegetable processing by-products (Table 3).Total DF content of the three orange DF concentra

50、tes di.ered with orange variety (Table 1). DFconcentrate from Valencia Late showed the highest content (% DM) while that from Navel hadthe lowest (Table 1). As regards insoluble and soluble fractions of total DF, Valencia Late was significantly di.erent from the other two varieties, Navel an

51、d Salustiana, with the highest proportion of insoluble DF (%DM) and the lowest proportion of soluble DF (.3% DM).The main components of the insoluble fraction were neutral sugars, representing approximately 60%. The highest proportion of neutral sugars was found in orange DF concentrate from

52、 var. Salustiana and the lowest from var. Navel (Table 4). Klason lignin (.2% DM) and insoluble uronic acids (%DM) were highest in orange DF concentrate from Valencia Late.The soluble fraction of orange DF concentrates contained more uronic acids than neutral sugars (Table 4).According to McP

53、herson Kay (1982), the ripening of the plant cell is associated with a gradual shift in fiber composition toward increasing proportions of cellulose and lignin. In this study, the DF concentrate from Valencia Late, which came from the ripest fruit, did have the highest Klason lignin content, while c

54、ellulose and hemicelluloses, represented by neutral sugars, did not vary with the ripeness index.The orange DF concentrates were high in uronic acids (approximately 45% total DF) (Table 4) indicative of high proportions of pectins. These substances have important applications in the pharmaceutical i

55、ndustry for their anti-diarrheal and detoxicant activities and for their regulation and protection of the gastro-intestinal tract (Pilnik and Voragen, 1992).Water and oil holding capacitiesThe WHC of orange DF concentrates was high, indicating that this material could be used as a functionalingredie

56、nt to reduce calories, avoid syneresis and modify the viscosity and texture of formulated foods (Table 5 and Table 6). The WHC of DF concentrates from Navel and Salustiana oranges (10.02 and 10.32 g water/g fiber, respectively) were higher than that from Valencia Late (7.3 g water/g diber) (Table 6)

57、. Both concentrates, from Navel and Salustiana, also had higher soluble DF content (Table 1) which is attributed to the WHC (McBurney et al., 1985; Adams et al., 1986).The OHC in the three orange DF concentrates were similar (Table 6) to those obtained by Chevalier (1993)in pea fiber and by Femenia

58、et al. (1997) in cauliflower fiber. This property makes these DF concentratesappropriate for stabilization of foods with a high percentage of fat and emulsions.Proximate compositionThe moisture of DF concentrates depends primarily on the intensity of the pulp dehydration during the processing of DF

59、concentrates. Indule rida, S.A. kept the moisture of all the orange DF concentrates under 10% to avoid the growth of microorganisms.Significant di.erences in the carbohydrate content of the orange DF concentrates were found among varieties. Valencia Late had the highest, followed by Navel, while Salustiana DF concentrate had the lowest (Table 7). These di.erences could be due to the ripeness of the original oranges because, according to Salu