香蕉皮中果胶提取工艺的研究

采用盐析的沉淀方法对香蕉皮果胶的提取工艺进行了系统研究。通过L9(34)正交实验,得出酸解工艺的最优化条件为:以pH1.5的盐酸溶液为萃取剂、液料比5mL/g、温度95℃、时间2h、螯合剂六偏磷酸钠添加量为0.3%;盐析的最优化条件为:每100mL果胶液中加入7mLAl2(SO4)3饱和溶液,边均匀搅拌边用浓氨水调pH至4.5左右,70℃保温45min;果胶盐脱盐的条件为:每5g果胶盐置于200mL脱盐液(组成为60%乙醇 3%盐酸 37%水,V/V)中,边搅拌边脱盐30min左右,所得果胶产量0.7846g。     

Rheological and functional properties of flours from banana pulp and peel

Unripe banana flour can be an alternative to minimize post‐harvest loss and to increase the aggregate value of banana fruit. Flour from unripe banana is rich in phytosterols and resistant starch, being proposed as health food. Flours from unripe banana peel and pulp were evaluated on their composition, phytosterols content, thermal and rheological properties, and pasting profiles. High amounts of β‐sitosterol, campesterol, and stigmasterol were found in flour from banana peel. These samples showed lower viscosity values of pasting profiles, lower energy enthalpy on gelatinization, and higher temperature of gelatinization than those ones from pulp. Anti‐oxidant treatment of fruits with citric acid does not change pasting profiles of flours from pulp, but resulted in slight increase in viscosity, suggesting that structure of starch could be modified by acidification.     

超声波协同草酸铵法提取香蕉皮中果胶的研究

该文研究采用超声波辅助草酸铵法提取香蕉皮中果胶的最佳工艺条件,研究了不同草酸铵浓度、料液比、超声功率、超声时间、超声温度和浸提时间对果胶提取率的影响。通过正交试验确定提取香蕉皮果胶的最优工艺条件为:草酸铵浓度0.8%,超声温度65℃,料液比35︰1,超声时间65 min,此条件下香蕉皮果胶的提取率为23.27%。     

Modification of pectin polysaccharides during ripening of postharvest banana fruit

Pectin is one of the major components of the primary cellular walls and middle lamella in plant tissues. In this study, water-soluble pectin (WSP) and acid-soluble pectin (ASP) fractions were isolated from pulp tissues of banana fruit at various ripening stages. Their monosaccharide compositions, glycosyl linkages and molecular mass distributions were evaluated. As ripening progressed, fruit firmness decreased rapidly, which was associated with the increase in the WSP content and the decrease in the ASP content. Meanwhile, the molecular mass distributions of WSP and ASP fractions exhibited a downshift tendency, indicating the disassembly of pectin polysaccharides. Moreover, galactose and galacturonic acid as the major monosaccharide compositions of pectin polysaccharides increased in WSP fraction but decreased in ASP fraction during fruit softening. GC–MS analysis further revealed that pectin polysaccharide had a 1,4-linked galactan/galacturonan backbone with different types of branching and terminal linkages in WSP and ASP fractions. During banana fruit ripening, the amount of 1,4-linked Galp residues of ASP fraction decreased significantly whereas 1,3,6-linked Galp, 1,2-linked Manp and 4-linked Araf residues disappeared, which was related to depolymerization of pectin polysaccharides. Overall, the study indicated that the modifications in polysaccharide compositions and glycosyl linkages, reduced molecular mass distributions and enhanced depolymerization of pectin fraction during banana ripening were responsible for fruit softening.     

Effect of extraction method and ripening stage on banana peel pigments

Carotenoids are one of the most widespread pigments in nature and can be used as health‐promoting natural food colorants. Banana peel, which is a by‐product of banana processing, contains a range of bioactive compounds including carotenoids. There is no published research on the extraction of food‐grade carotenoids from banana peels. This study evaluated the change in the banana peel carotenoid content over its ripening stages and determined the best possible solvent to extract carotenoid for food applications. The solvents permitted under Food Standard Australia New Zealand were used in the study. Ripeness stage 5 contained the highest content of total carotene at 1.86 μg g^?1 of banana peel. From one gram of banana peel, 0.57 μg of xanthophyll and 0.84 μg of beta‐carotene were extracted from ripening stage 5 with a solvent combination of hexane–diethyl ether–acetone and hexane–diethyl ether, respectively.     

微切变-助剂互作技术辅助提取柑橘皮果胶的工艺研究

目的建立并优化微切变-助剂互作技术提取橘皮果胶的工艺方法。方法采用固态氯化钠为助剂,雪峰蜜橘为主要原料,以果胶的提取率为评价指标,采用单因素和正交实验探索果胶的最优提取工艺,包括Na Cl助剂量、浸提时间、料液比、提取液pH 4个单因素。结果最优工艺条件为:助剂添加量2.5%(m:m)、浸提时间80 min、料液比1:20(m:V,g:mL)、提取液pH为2,此条件下果胶提取率为23.16%,比对照组提高了48.18%,且提取总时长由242 min缩短到102 min。结论以氯化钠为助剂的微切变-助剂互作技术高效省时、安全可靠,为柑橘副产物的高附加值综合利用提供了理论参考。     

Comparing physicochemical properties of banana pulp and peel flours prepared from green and ripe fruits

Banana pulp and peel flour prepared from green and ripe Cavendish banana were assessed for physicochemical properties such as pH, total soluble solids (TSS), water holding capacity (WHC) and oil holding capacity (OHC) at 40, 60 and 80 °C, colour values L^∗, a^∗ and b^∗, back extrusion force (BEF) and viscosity. Data obtained were analysed by MANOVA, discriminant analysis and cluster analysis. All statistical analyses showed that physicochemical properties of flour prepared from pulp and peel, and green and ripe banana were different from each other. TSS, WHC40, WHC60 and BEF can be used to discriminate between peel and pulp flour, whilst TSS and viscosity can be used to discriminate between flour prepared from green and ripe banana.     

大孔吸附树脂对香蕉皮多酚吸附特性的初步研究

研究了8种大孔吸附树脂对香蕉皮多酚的静态吸附和解吸性能，筛选出吸附和解吸性能较好的树脂，并对其进行了动态吸附与解吸研究。实验结果表明：DM-301树脂具有较好的吸附和解吸效果，确定吸附流速为2 BV／h．浓度为3mg／mL，乙醇洗脱浓度为70％。     

柚皮果胶理化性质的研究

以柚皮干粉为原料提取果胶,采用正交实验优化柚皮果胶提取工艺,并对其理化性质进行检测。研究表明在提取温度100℃,pH2.0,时间60min,料液比1∶50(g/mL)的条件下柚皮果胶的得率最高,为27.06%,纯度达84.3%,酯化度为73.75%,所得果胶为淡黄色。常温下pH为4.86,属于酸性高酯果胶。柚皮果胶的溶解度随温度升高而增大、随着pH增大,溶解度有下降的趋势;柚皮果胶的热稳定性优于商品果胶,但随着时间增加迅速降低,15min后趋于稳定;柚皮果胶粘度与果胶浓度和蔗糖浓度的正相关,随pH的增大和温度的升高而下降;柚皮果胶理化性质与商品柑橘果胶相似,柚皮果胶的粘度和乳化性能优于商品柑橘果胶。实验结果表明柚皮果胶是一种优质的果胶。      

Rheological Properties of Wheat (Halberd) Amylopectin

The non‐Newtonian flow behavior and dynamic viscoelasticity of wheat (Halberd) amylopectin in aqueous solution were investigated. The flow curves of Halberd amylopectin at 25 °C showed shear‐thinning behavior at various concentrations (2.0, 4.0 and 6.0%). The viscosity decreased gradually with increase in temperature at all concentrations investigated. The storage modulus of Halberd amylopectin was rather small and decreased gradually during increase in temperature even in 6.0% solution. The tan δ showed a value of 1.8 at 6.0% even at low temperature (0 °C) and increased slightly with increase in temperature. The storage modulus of Halberd amylopectin (6.0%) increased slightly upon addition of urea (4.0 M) and decreased gradually with increase in temperature. The storage modulus was higher in 0.05 M aqueous NaOH solution (6.0%) than in pure water. However, for tan δ almost the same values were observed in aqueous urea (tan δ = 1.7) and in alkaline (tan δ = 1.6) solution as in pure water (tan δ = 1.8). The storage modulus had a very large value in 85% DMSO. However, the tan δ value in DMSO was almost identical to that in aqueous solution. The results obtained led to the suggestion that in aqueous solution the wheat (Halberd) amylopectin molecules might be involved to a little extent in secondary associations. The structure of wheat (Halberd) amylopectin molecules seems to be different from that of rice amylopectin molecules.     

Physicochemical properties of sugar beet pulp pectin by pulsed electric field treatment

This research focused on pulsed electric field (PEF) modification of pectin from sugar beet pulp. Experimental parameters including electric field intensity (18–30 kV cm^?1) and pulse time (806–2418 μs) were used, and the physicochemical properties of PEF‐treated pectin were evaluated by various instrumental techniques such as scanning electron microscopy, X‐ray diffraction, dynamic light scattering and Fourier transform infrared spectroscopy. The results showed that the degree of esterification, viscosity average molecular weight and particle size of pectin decreased with the increase in electric field intensity and pulse time. Meanwhile, some sharp interstices were shown on the surface of pectin, and its crystalline regions were destroyed after being treated with PEF. Results revealed that PEF technology is an effective method to obtain low‐molecular‐weight pectin with different degrees of esterification and obtain a desired production in food application.     

内源果胶酯酶制备低甲氧基果胶的研究

以新鲜橙皮为原料，在盐酸水解乙醇沉淀提取果胶之前，激活并利用果皮中固有的果胶酯酶进行果胶的酶法脱酯，制备低甲氧基果胶，以产品的甲氧基含量和果胶得率为指标，确定最佳工艺条件。结果表明新鲜橙皮内源酶法制备低甲氧基果胶的最佳工艺条件为：加入果皮浆液量0．15％的内源性果胶酯酶激活剂碳酸钠，控制温度45℃，pH值8．0进行脱酯，时间60min；果胶提取温度90％，时间60min，pH值2．0；在此条件下制备的果胶甲氧基含量为5．93％，符合低甲氧基果胶标准，果胶得率为2．46％。     

柑橘皮渣中高酯果胶的提取与纯化

以柑橘皮渣为原料,采用离子交换树脂提取法与大孔吸附树脂纯化法来制备高,酯果胶,通过单因素及正交试验确定果胶的最佳提取工艺为料液比1:20(m:V),离子交换树脂含量4%,pH 1.7,温度85℃,时间140 min,此时粗果胶提取率19.806%;在纯化工艺研究中,通过对AB-8树脂使用次数及不同恒流泵流速的研究,确定最佳流速4 BV/h,此时脱色率为54.45%,果胶纯化得率为95.32%.柑橘果胶实际得率为18.88%,酯化度为53.75%,半乳糖醛酸含量和分子量分别为75.26%和62 040,其他基本性质如灰分(1.20%)、0.1%溶液pH(3.201)、干燥失重(8.56%)等均达到国标要求,表明该方法适宜用于提取高酯果胶.     

Effect of extraction conditions on the yield, purity and surface properties of sugar beet pulp pectin extracts

The extraction of pectins from sugar beet pulp was carried out in an aqueous acid medium under different conditions using a full two-state experimental design for three extraction parameters (pH, temperature and time). The yields of the extracted pectins ranged from 4.1% to 16.2%. Their contents in pectin constituents were 35.2–76.3% galacturonic acid, 6.8–32.9% neutral sugars, 2.0–4.2% methoxy groups, 0.8–3.8% acetyl groups, and 0.1–0.7% ferulic acid. Moreover, protein residues were present in all the extracts within the range of 0.9–6.8% and varied with the extraction conditions. On high performance size exclusion chromatography, the elution pattern of the acid-extracted pectins showed a wide molar mass distribution consisted of two relatively broad peaks. Their weight-average molar mass values determined by HPSEC-RALLS ranged widely from 20,200 to 90,100 g/mol. Most of the extracted pectins were surface-active, and some of them were quite able to produce and stabilize with effectiveness oil-in-water emulsions. Thus, it was inferred that yield, physico-chemical characteristics and surface properties of acid extracted pectins from sugar beet pulp were influenced by the extraction conditions.     

Sustainable production of pectin from lime peel by high hydrostatic pressure treatment

The application of high hydrostatic pressure technology for enzymatic extraction of pectin was evaluated. Cellulase and xylanase under five different combinations (cellulase/xylanase: 50/0, 50/25, 50/50, 25/50, and 0/50 U/g lime peel) at ambient pressure, 100 and 200 MPa were used to extract pectin from dried lime peel. Extraction yield, galacturonic acid (GalA) content, average molecular weight (M_w,ave), intrinsic viscosity [η]_w, and degree of esterification (DE) were compared to those parameters obtained for pectins extracted using acid and aqueous processes. Pressure level, type and concentration of enzyme significantly (p < 0.05) influenced yield and DE of pectin. Enzyme and high pressure extraction resulted in yields which were significantly (p < 0.05) higher than those using acid and aqueous extraction. Although pressure-induced enzymatic treatment improves pectin yield, it does not have any significant effect on M_w,ave and [η]_w of pectin extracts indicating the potential of high pressure treatment for enzymatic pectin production as a novel and sustainable process.     

The effect of pectin concentration on viscoelastic and sensory properties of processed cheese

The effect of pectin addition on viscoelastic properties of model processed cheeses with 40% w/w dry matter and 50% w/w fat in dry matter after 42 days of storage at temperature 6 ± 2 °C has been investigated using dynamic oscillation rheometry (plate–plate geometry; frequency range 0.1–50.0 Hz; temperature 20 °C). The role of pectin concentration (0.2%, 0.4%, 0.6% and 0.8% w/w) has been studied. Also, the sensory evaluation of samples has been made to assess cheese appearance, rigidity, spreadability and flavour. All samples with the pectin addition were more rigid and less spreadable compared with processed cheeses without pectin. With the increasing concentration of pectin the storage ( G ') and loss ( G ") moduli rose at the whole tested frequency range (0.1–50.0 Hz). Growing pectin content resulted in the decrease in loss tangent (the nature of gel was changed to more elastic material). The dependence of processed cheese rigidity on pectin concentration (in range 0–0.8% w/w) was not linear. The appearance and flavour were not worse by pectin addition.     

Rheological properties of Lepidium sativum seed extract as a function of concentration, temperature and time

The seeds of Lepidium sativum (Garden Cress) were selected as a new source of hydrocolloid and its chemical composition and molecular parameters were determined. The macromolecular component of the extract had a molecular weight of 540 kDa, and was nearly as rigid as xanthan with regard to chain conformation. The main rheological features were investigated as a function of shear rate, concentration and temperature. The extract exhibited strong shear-thinning behaviour, which was even more pronounced than for xanthan. An increase in concentration or temperature led to an increase in pseudoplasticity. The Arrhenius model was applied to the temperature dependence of viscosity, and the activation energy (E_a) was found to decrease with increasing concentration. The extract solutions showed thixotropic behaviour at all the concentrations and temperatures studied, and the first-order stress decay model with a non-zero equilibrium stress fairly described the time-dependent behaviour. The rheological characteristics found indicated a potential application of the extract as a novel thickener.     

响应面优化提取血柚皮果胶的工艺研究

采用响应面法优化了血柚皮果胶的提取工艺,在单因素实验基础上,选取柠檬酸浓度、提取温度、液料比和提取时间为自变量,果胶得率为响应值,根据Box-Behnken实验设计方法,对提取血柚皮果胶的关键因素参数进行了优化,建立了血柚皮果胶得率的数学模型。结果表明:四个因素对血柚皮果胶得率的影响大小依次为提取温度>柠檬酸浓度>液料比>提取时间;血柚皮果胶提取的最佳工艺参数为:柠檬酸浓度1.5%,提取温度82℃、液料比32∶1m L/g、提取时间99min。在此条件下,血柚皮果胶得率达18.85%,与预测值仅相差0.32%,验证了数学模型的有效性。      

超声波辅助酸法提取柚皮果胶生产工艺的研究

以柚皮为原料,研究了料液比、超声功率、超声温度、超声时间对柚皮果胶提取得率的影响,在单因素试验的基础上通过正交试验设计优化柚皮果胶的提取工艺条件。结果表明,柚皮果胶提取的最佳工艺条件:料液比1 g∶15 m L,超声功率150 W,超声温度为80℃,超声时间为40 min。采用优化工艺提取果胶,产品总得率达22.76%。