微波辅助提取桔皮果胶的理化及凝胶特性比较

为了增加桔皮利用率,提高桔皮中果胶得率和品质,以5种新鲜桔皮(丑橘、砂糖橘、芦柑、金橘、贡桔)为原料,采用微波辅助法提取桔皮中果胶,对果胶理化特性和凝胶特性进行研究。分析果胶理化及凝胶特性的相关性,并采用主成分分析法确定影响果胶凝胶特性的主要因素,优化微波辅助法提取工艺参数。结果表明:5种桔皮果胶都是高酯果胶,5种果胶理化及凝胶特性存在显著差异(P0.05),其中芦柑果胶得率和半乳糖醛酸质量分数最高,分别为12.36%、78.61%;且5种果胶理化及凝胶特性呈显著相关性(P0.05),主成分分析法确定甲氧基质量分数和果胶得率分别为主成分1和2中主要影响因子,甲氧基质量分数决定果胶种类,因此果胶种类和得率是桔皮果胶提取的主要因素。微波提取优化参数:以芦柑桔皮为原料,料液比为1:26 g/g,p H值1.30,微波功率440 W,微波时间62 s,果胶得率为16.00%。研究结果为桔皮果胶加工和应用提供理论指导。     

微波辅助提取中pH值与脱色对苹果果胶的影响

为了得到高得率、高品质的苹果果胶,该文利用不同pH值的盐酸溶液对苹果渣中果胶进行微波辅助提取（Microwave-assisted extraction, MAE）,之后对果胶提取液进行大孔树脂XAD-16HP脱色,研究了pH值与脱色对果胶得率和品质的影响。结果表明：微波辅助提取工艺中随着pH值的升高,果胶得率、半乳糖醛酸质量分数和总离子含量减少,酯化度、黏均分子量和总多酚增加,褐变度无显著变化;大孔树脂吸附脱色后果胶褐变度、总多酚、彩度C*值显著下降,色调角H°值显著增加,半乳糖醛酸质量分数和酯化度没有     

豆皮果胶类多糖的提取及其在大豆蛋白凝胶类食品的应用

为提高大豆副产物利用率,拓展豆皮果胶类多糖（Soybean Hull Pectin Polysaccharide, SHPP）在凝胶类食品的应用,该研究采用盐辅助结合水热处理技术提取大豆豆皮中的豆皮果胶类多糖,并对其基本理化性质进行表征。通过以大豆蛋白为主要成分的凝胶类食品豆腐花为模型,探究不同添加量豆皮果胶类多糖（0～2.0%）与大豆蛋白的离散型相分离行为,分析其微相分离行为与宏观流变学性质、机械性能、持水性与感官评定的关联性,并与商品化柑橘果胶（Citrus Pectin, CP）作对比。结果表明,该提取法所得豆皮果胶类多糖提取率为17.95%±0.21%,其半乳糖醛酸含量为42.13%±2.05%,平均粒径为（210.3±2.9）nm,多分散性指数（Polydispersity Index, PDI）为0.466±0.037,豆皮果胶类多糖具有良好的亲水性和低黏度特性,易分散于水。添加0～0.5%豆皮果胶类多糖制备豆腐花,发现其微观上无相分离产生,具有良好的网络微结构;宏观上表现为外观白嫩,黏弹性、持水性与口感均良好。添加1.0%豆皮果胶类多糖的豆腐花宏观上出现明显析水,凝胶黏弹性和持水性均显著（P<0.05）减少。继续增加豆皮果胶类多糖至1.5%添加量则会导致相分离产生,蛋白凝胶网络微结构变得无序,网状孔隙增大,凝胶强度进一步减弱,保水性极差（46.2%±3.2%）。由此确定,豆皮果胶类多糖适宜添加量为0.5%。与经优化的柑橘果胶添加量为0.1%的豆腐花作比较,发现添加0.5%豆皮果胶类多糖的豆腐花在质构特性以及色泽、组织状态、滋味气味、口感、可接受度各方面的感官评分上均优于含柑橘果胶的豆腐花。结果表明豆皮果胶类多糖更适用于蛋白凝胶类食品。研究结果为豆皮果胶类多糖的应用开发,大豆副产物的再利用以及全豆食品的发展提供一定推动作用。     

超高压辅助酶法制备低酯果胶

为明确超高压辅酶法在低酯果胶生产中的可行性,该研究以传统碱法为对照,研究了超高压(200、300 MPa)辅助果胶甲酯酶法对果胶的理化性质、分子量分布及流变性质的影响。结果表明,与传统碱法相比,超高压辅酶法制备的低酯果胶的表观黏度、固有黏度及黏均分子量均显著大于碱法低酯果胶(P0.05),而黏流活化能较低(P0.05),说明其黏-温敏感性更低。通过尺寸排阻色谱分析,超高压辅酶法制备的低酯果胶与脱酯前没有显著性差异(P0.05),说明该法对果胶分子无降解作用。以上结果表明超高压辅酶法(200、300 MPa)避免了传统碱法的果胶分子降解,该法制备的低酯果胶黏度更高,可作为一种制备低酯果胶的高效、环保的新型技术。     

传统与微波辅助工艺提取苹果果胶品质比较

该研究比较了传统工艺（CSE）与微波辅助工艺（MAE）所提取苹果果胶的品质差异,微波工艺[pH=1.0,提取时间20.8 min,功率499 W,料液比=1︰14.5（m/V）]提取的苹果果胶其得率、纯度和总离子含量均显著高于传统工艺[pH=2.0,提取时间1.5 h,温度85℃,料液比=1︰13],动态模式下对果胶溶液凝胶性能分析发现,传统工艺提取的苹果果胶凝胶温度为94℃,微波工艺提取的温度为82℃,但其酯化度和黏均分子质量显著小于传统工艺;传统工艺提取的苹果果胶溶液褐变指数、屈服应力、表观黏度、活化能显著高于微波工艺,总酚含量显著低于微波工艺;传统工艺提取苹果果胶溶液的亮度值和色调角均高于微波工艺,彩度值低于微波工艺提取的苹果果胶;频率扫描发现,传统工艺提取的果胶溶液具有更加稳定的三维结构,分子间相互结合得更加紧密,具有更好的凝胶特性。     

鸡蛋壳膜角蛋白不同提取工艺的效果比较

为探索不同方法提取的鸡蛋壳膜角蛋白的得率及其结构的区别,为鸡蛋壳膜角蛋白工业化生产方法的选择提供理论依据,分别采用氢氧化钠碱法、过氧化氢氧化法、碱性蛋白酶法从鸡蛋壳膜中提取角蛋白,以其反应速率及产品角蛋白的得率、分子量、结构完整性等为指标,比较3种不同提取方法对鸡蛋壳膜角蛋白性质的影响。试验比较结果表明,角蛋白得率:氧化法(24.33%)碱法(19.31%)酶法(15.19%);反应速率:氢氧化钠碱法最快,过氧化氢氧化法次之,碱性蛋白酶法最慢;角蛋白分子量:碱性蛋白酶法(31~43 kDa)氢氧化钠碱法(14.4~20.1 kDa)过氧化氢氧化法(14.4 kDa);角蛋白结构:碱性蛋白酶法和氢氧化钠碱法提取的角蛋白,二级结构保存完整,过氧化氢氧化法提取的角蛋白二级结构受到了破坏。氢氧化钠碱法和碱性蛋白酶法可用于生产分子量高、二级结构完整的角蛋白产品,而过氧化氢氧化法是生产小分子肽类角蛋白产品较好的方法。     

微波加热法提取柚果皮果胶的工艺（简报）

对新鲜柚果皮中果胶进行微波提取,采用咔唑比色法测定提取液中的果胶含量.探讨了料液比、微波功率、微波处理时间、盐析条件等对果胶得率和半乳糖醛酸含量的影响,运用L9(34)正变试验对微波加热提取果胶的工艺条件进行了优化.结果表明:微波功率对果胶得率有极显著影响,微波处理时间影响较小.较佳工艺是:液料比(V/m)8:1,调pH值为2.0,微波功率640W,处理时间8 min,盐析饱和硫酸铝用量与酸萃取液比例为3:5,此条件下提取柚皮果胶得率为4.457％,果胶的半乳糖醛酸含量为42.58％．     

柚子皮基可食性膜的制备及性能研究

为了促进果蔬加工副产物的高附加值利用,以柚子皮干粉为材料,海藻酸钠为增稠剂,甘油为增塑剂,采用流延法制备了柚子皮基可食性膜,分析柚子皮干粉质量分数、海藻酸钠、甘油质量分数对柚子皮基膜力学性能、阻湿性能和透光率等的影响,并对柚子皮基膜的制备配方进行优化。结果表明,柚子皮基膜的最佳制备配方为:柚子皮干粉质量分数3%、海藻酸钠质量分数0.15%(以柚子皮粉浆料质量为基础,下同)、甘油质量分数0.5%,此配方制备的柚子皮基膜外观平滑、颜色淡黄,具有较好的综合性能,其拉伸强度为17.53±0.35 MPa,断裂伸长率为19.46%±0.43%,水蒸气透过系数为(2.327±0.128)×10^-12g·cm^-1·s^-1·Pa^-1,透光率为63.2%±0.15%。本研究结果为柚子皮基可食性膜在食品包装等领域的应用提供了理论参考。     

工艺条件对猪皮提取物质构和微观结构影响的初步研究

为了给猪皮提取物在肉制品加工中的应用创造条件,采用单因素试验,分别测定不同提取条件(煮沸时间、料液比、pH值、盐浓度)下凝胶质构和微观结构的变化,在此基础上,采用正交试验优化提取条件。单因素试验表明煮沸时间、料液比、提取液pH值对猪皮提取物的质构特性都有显著影响,煮沸时间为60min、料液比为1:5、提取液pH值为5时形成的凝胶最好,盐浓度对质构特性无显著影响。正交试验表明,料液比1:5,盐浓度为3%,煮沸时间60min,pH=6的提取条件下获得的提取物凝胶的质构特性及微观结构最好。     

适量卵磷脂改善低酯苹果果胶凝胶流变性

为了进一步了解卵磷脂在果胶凝胶中的作用,该文考察卵磷脂对果胶凝胶流变性的影响,以低酯苹果果胶为原料,在钙离子浓度为12 mmol/L条件下,加入质量分数0.2%~1.2%的卵磷脂,考察凝胶过程中储能模量(G′)与损耗模量(G″)变化。通过凝胶结构形成速度(structure developing rate,SDR)流变学分析方法探讨在果胶凝胶过程中卵磷脂对凝胶体系的影响,结果显示:卵磷脂的添加对果胶钙凝胶的形成速度(SDR)和储能模量(G′)有影响,在整个温度变化范围内,卵磷脂添加量小于0.4%时对SDR曲线和G′曲线的影响不明显;卵磷脂添加量为0.4%时SDR曲线和G′曲线明显上升,显示出较快的凝胶速度和较强的凝胶强度;当卵磷脂添加量大于0.4%时,SDR曲线和G′曲线下降。凝胶形成动力学研究显示,加入0.4%的卵磷脂,使果胶的凝胶过程在高温区和低温区的差别更大,活化能差别也较大(P0.05):高温区活化能为290.6 k J/mol,低温区活化能为67.1 k J/mol。电镜扫描显示添加0.4%卵磷脂的果胶钙凝胶结构更为均匀紧密。研究结果为卵磷脂/果胶体系的应用提供理论参考数据。     

Monovalent salt-induced gelation of enzymatically deesterified pectin

Pectin gels were induced by monovalent salts (0.2 M) concurrently with deesterification of high methoxy pectin using a salt-independent orange pectin methylesterase (PME). Constant pH was maintained during deesterification and gelation. If salt or PME was absent, the pectin did not form a gel. The gel strength was influenced by both pH and species of monovalent cation. At pH 5.0, the pectin gel induced by KCl was significantly stronger than the NaCl-induced gel. In contrast, a much stronger gel was produced in the presence of NaCl as compared to KCl at pH 7.0. LiCl did not induce pectin gelation at either pH. Molecular weights of pectins increased from 1.38 x 10(5) to 2.26 x 10(5) during NaCl-induced gelation at pH 7. One proposal to explain these pectin molecular weight changes is a hypothetical PME transacylation mechanism. However, these pectin molecular weight changes can also be explained by metastable aggregation of the enzymatically deesterified low methoxy pectin. We postulate that gelation was induced by a slow deesterification of pectin under conditions that would normally salt out (precipitate) low methoxy pectin in the absence of PME.     

Extraction of green labeled pectins and pectic oligosaccharides from plant byproducts

Green labeled pectins were extracted by an environmentally friendly way using proteases and cellulases being able to act on proteins and cellulose present in cell walls. Pectins were isolated from different plant byproducts, i.e., chicory roots, citrus peel, cauliflower florets and leaves, endive, and sugar beet pulps. Enzymatic extraction was performed at 50 degrees C for 4 h, in order to fulfill the conditions required for microbiological safety of extracted products. High methoxy (HM) pectins of high molar mass were extracted with three different enzyme mixtures. These pectins were subsequently demethylated with two pectin methyl esterases (PMEs), either the fungal PME from Aspergillus aculeatus or the orange PME. It was further demonstrated that high molar mass low methoxy (LM) pectins could also be extracted directly from cell walls by adding the fungal PME to the mixture of protease and cellulase. Moreover, health benefit pectic oligosaccharides, the so-called modified hairy regions, were obtained after enzymatic treatment of the residue recovered after pectin extraction. The enzymatic method demonstrates that it is possible to convert vegetable byproducts into high-added value compounds, such as pectins and pectic oligosaccharides, and thus considerably reduce the amount of these residues generated by food industries.     

Enzymatic modification of pectin to increase its calcium sensitivity while preserving its molecular weight

A commercial high-methoxy citrus pectin was treated with a purified salt-independent pectin methylesterase (PME) isozyme isolated from Valencia orange peel to prepare a series of deesterified pectins. A series of alkali-deesterified pectins was also prepared at pH 10 under conditions permitting beta-elimination. Analysis of these pectins using high-performance size exclusion chromatography (HPSEC) with on-line multiangle laser light-scattering, differential viscometer, and refractive index (RI) detectors revealed no reduction in weight-average molecular weight (M(w); 150000) in the PME-treated pectin series, whereas a 16% reduction in intrinsic viscosity (IV) occurred below a degree of esterification (DE) of 47%. In contrast, alkali deesterification rapidly reduced both M(w) and IV to less than half of that observed for untreated pectin. PME treatment of a non-calcium-sensitive citrus pectin introduced calcium sensitivity with only a 6% reduction in the DE. Triad blocks of unesterified galacturonic acid were observed in (1)H nuclear magnetic resonance spectra of this calcium-sensitive pectin (CSP). These results demonstrate that the orange salt-independent PME isozyme utilizes a blockwise mode of action. This is the first report of the preparation of a CSP by PME treatment without significant loss of the pectin's M(w) due to depolymerization.     

Yellow passion fruit rind--a potential source of low-methoxyl pectin

Yellow passion fruit (Passiflora edulis f. flavicarpa Degener) rind pectic substances were fractionated with water, ammonium oxalate, and dilute acid solutions. The extracted pectins were rich in anhydrogalacturonic acid and had a low degree of methyl esterification. Moreover, their acetyl groups and neutral sugar contents were relatively low. Furthermore, a low amount of proteinaceous material was also found within them. Their gelling ability and viscoelastic properties as evaluated by the SAG and small amplitude oscillatory shear tests, respectively, were comparable to those of a commercial citrus low-methoxyl pectin. Hence, yellow passion fruit rind occurs as a potentially good source of naturally low-methoxyl pectin.     

Particle size distribution of orange juice cloud after addition of sensitized pectin

The effect of the addition of commercial pectin to orange juice that was de-esterified by alkaline treatment or pectinmethylesterase was evaluated. Pectin at various degrees of esterification (DE) was added to reconstituted frozen orange juice concentrate, and the extent of cloud loss was determined after centrifugation. Of the five pectin treatments, percent transmittance (% T) of juice remained <5%, except for the pectin treatment with a residual methoxyl content (% DE) of <5%. Addition of 100--600 ppm of 5% DE pectin to juice resulted in % T between 36 and 73%. Despite the absence of clarification, increases in cloud particle size were observed and depended on the % DE, the amount of pectin added, and the method used to modify the pectins.     

Seasonal Changes of Mineral Nutrients in Fruit and Leaves of ‘Newhall’ and ‘Skagg's Bonanza’ Navel Oranges

In southern Jiangxi province of China, ‘Newhall’(Citrus sinensis Osbeck) navel orange presented a conspicuous symptom of boron (B) deficiency in mature leaves, whereas B deficiency symptoms were not manifested on ‘Skagg's Bonanza’(C. sinensis Osbeck) navel orange. In this study, changes in concentrations of B, calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) were comparatively investigated in the structural parts of the fruit (rind and pulp) and leaves (old leaves from last season and spring-flush leaves from current year) of ‘Newhall’ and ‘Skagg's Bonanza’ navel orange during the growing season. Two peaks of B concentrations were observed in the rind of the two cultivars during fruitlet growth and fruit enlargement, respectively. Boron concentrations were relatively high in the rind during fruitlet growth, and then decreased in both rind and pulp, whereas, during middle and late fruit enlargement significant increases were found for B in both rind and pulp of the two cultivars. Boron concentrations in old leaves of ‘Newhall’ decreased progressively and remained relatively low, whereas that of ‘Skagg's Bonanza’ was relatively high and changed slightly as the season progresses. Both Ca and K concentrations were above the critical threshold values, while their dynamics were reverse to that of B in fruit and leaves during certain times. Old leaf Mg concentrations of samples at 140 days after full bloom from the two cultivars and spring-flush leaves from ‘Newhall’ were below the threshold limit for sufficiency. In addition, Mg in old leaves was much lower from ‘Newhall’ than from ‘Skagg's Bonanza’. Spring-flush leaf concentrations of Mn and Zn and Mn concentrations in old leaves from ‘Newhall’ were relatively lacking during middle and late season, which accelerated the occurrence of B deficiency symptoms on mature leaves of ‘Newhall.’     

氯化钾对脐橙园土壤–树体氯积累及叶片营养和果实品质的影响

  【目的】  探讨施用氯化钾对脐橙叶片营养、果实产量及品质的影响,分析土壤和植株中氯元素含量与积累状况。  【方法】  以9年生纽荷尔脐橙为试材,于2018—2019年连续进行了两年田间试验。脐橙果园土壤一个为酸性、一个为碱性。氯化钾年施用量处理为250 g/株 (T1)、500 g/株 (T2)、1000 g/株 (T3),以硫酸钾556 g/株为对照 (CK)。在果实成熟期,测定了春梢和秋梢叶片中的N、P、K、Ca、Mg、Cl元素和相对叶绿素含量,测产并取样测定了果实品质及Cl–含量,在施肥后测定了0—20和20—40 cm土壤中的Cl–含量。  【结果】  1) 施用不同量氯化钾后果皮、果肉中氯元素含量没有显著变化,土壤和叶片中氯元素含量显著增加。T1处理在酸性土中氯元素含量较碱性土中多,与CK相比,T1处理酸性土中氯元素含量平均增加50.20%,而碱性土增加28.02%;T2处理氯元素含量在酸性土与碱性土中相差不大;T3处理氯元素含量在碱性土中大于酸性土中,与CK相比,酸性土增加79.70%,碱性土增加99.36%。2)T1处理下,在酸性土上脐橙春、秋梢叶片氯元素含量较CK分别增加了21.9%和8.0%,在碱性土上分别增加25.5%和12.7%;T2处理下,在酸性土上分别增加51.9%和45.0%,碱性土上分别增加33.3%和19.3%;T3处理下,在碱性土上分别增加109.7%和98.7%,而在酸性土上分别增加63.8%和58.0%。施用氯化钾后叶片中相对叶绿素、氮和钙元素含量没有显著变化,钾和部分磷元素含量随氯化钾施用量的增多呈增加趋势,镁元素含量略有下降。3) 施用氯化钾对果实产量、单果重、亮度、黄色度、可溶性固形物和可滴定酸含量均没有显著影响,部分果实红色度在施用氯化钾代替硫酸钾后显著提高,维生素C含量随氯化钾浓度的增高有增加趋势。  【结论】  短期施用氯化钾对果实中氯元素含量无显著影响,土壤和叶片中氯元素含量则显著增加,但均处在安全阈值以内。短期施用氯化钾对柑橘果实产量及品质无显著不良影响,叶片营养受影响较小,因此,酸、碱性土壤脐橙园短期内施用适量的氯化钾代替硫酸钾是可行的。     

Characterization of flavonoids and pectins from bergamot (Citrus bergamia Risso) peel, a major byproduct of essential oil extraction

Bergamot peel is an underutilized byproduct of the essential oil and juice-processing industry. As with other Citrus peels, it still contains exploitable components, such as pectins and flavonoids. Commercial glycoside hydrolases, specifically a combination of pectolytic and cellulolytic enzymes, solubilized a high percentage of the material (81.94%). The flavonoid profile of the peel consisted of characteristic Citrus species flavanone rutinosides and neohesperosides derived from naringenin, eriodictyol, and hesperetin. In addition, a number of minor flavanone and flavone glycosides, not found in orange and lemon peels, were identified. The majority of flavonoids were extracted in the two 70% v/v EtOH extractions. Processing this material clearly has economic potential leading to low environmental impact.     

Determination of lignans in edible and nonedible parts of pomegranate (Punica granatum L.) and products derived therefrom, particularly focusing on the quantitation of isolariciresinol using HPLC-DAD-ESI/MSn

A method for the characterization and quantitation of phyto-estrogenic lignans from pomegranate (Punica granatum L.) fruits and fruit-derived products by HPLC-DAD-MS(n) was developed. For this purpose, edible and nonedible parts of pomegranate (aril, peel, mesocarp, seed, and twigs), commercial juices, juices produced on pilot-plant scale, and encapsulated dietary supplements were analyzed. In addition to the peel, mesocarp, and twigs, lignans were detected in two juices obtained from entire fruits, four commercial juices, and three encapsulated pomegranate extracts. Isolariciresinol was the predominant lignan with contents of 5.0, 10.5, and 45.8 mg/kg dry matter in processed pomegranate mesocarp, peel, and twigs, respectively. In contrast, due to their low amounts, quantitation of lignans in pomegranate products was impossible. Therefore, contrary to previous assumptions, lignans were found to be less relevant in pomegranate-derived products. However, the byproduct from pomegranate processing may be used for lignan extraction. The method presented allows one to differentiate between pomegranate-derived products obtained from fruits without peels or by dejuicing applying low pressures, which were devoid of lignans, and those obtained from entire fruits applying high pressures, thus containing lignans. Consequently, this study helps to optimize process technology aiming at the recovery of preparations with well-desired compositions, which may reduce the risk of a wide range of diseases, such as certain types of cancer.