微生物与柑桔汁脱苦

对用于柑桔汁脱苦的微生物种类及其脱苦机理进行了综述,同时介绍了与脱苦有关的酶及微生物细胞的固定化在柑桔汁脱苦中的应用。     

水溶性食物纤维强化柑桔汁饮料的开发研究─再论中国产HB801吸附树脂对柑桔苦味物质的脱除效果

本试验对已吸附树脂脱苦处理后的柑桔皮果胶液，用于水溶性食物纤维强化柑桔汁饮料的开发进行了研究。在以前研究的基础上［１］，对３种吸附树脂不同处理的样品中残留的苦味成分柚皮苷和柠碱的含量，应用高效液相色谱仪进行了分析。证明了中国产ＨＢ８０１的脱苦效果稍优于目前国际果汁饮料业界常用的美国产ＡｍｂｅｒｌｉｔｅＸＡＤ－２等。同时还试制了已经ＨＢ８０１脱苦处理后的柑桔皮果胶液作为水溶性食物纤维的强化柑桔汁饮料。为使普通柑桔皮果胶液适用于饮料生产，本文作了一些探索。     

三种脱苦方法脱除柑桔汁苦味的研究

柠碱和柚苷是柑桔汁及柑桔其它制品中主要苦味成份。本文着重研究了酶法脱苦、β—环糊糟脱苦和乙烯利代谢脱苦三种方法脱除柑桔汁内苦味的效果和工艺实施。进行了黑曲霉(Aspergillus niger.)不同菌株产酶筛选试验,对由黑曲霉诱导产生的柚苷酶及其固定化柚苷酶的一些基本酶学特性进行了探索性研究,对β—环糊精脱苦的机制、工艺及效果也进行了研究,并提出了采用综合脱苦的方法应用于生产实际的措施。     

固定化醋酸杆菌细胞特性的研究

研究了用于柑桔汁脱苦的固定化醋酸杆菌细胞的特性,研究表明：固定化细胞脱苦最佳供氧为：摇床转速160r/min,最适pH为4.5,最适温度为25℃;而细胞脱苦的相应条件分别为160r/min,pH5.5,25℃。低浓度NaCl对固定化细胞和游离细胞的脱苦都有强烈的抑制作用;固定化细胞在柠碱浓度达到30mg/kg后,柠碱降解速度趋于饱和,而游离细胞的柠碱浓度则为35mg/kg;固定化细胞的热稳定性比游离细胞好。     

柑桔汁脱苦方法研究进展

对柑桔汁形成苦味的原因及目前柑桔汁脱苦方法的研究进展进行了综述,并提出了今后的研究方向。     

柑桔类果汁的脱苦技术

简要介绍了脱除柑桔类果汁苦味的一些技术。这些技术包括；代谢脱苦法、屏蔽脱苦法、吸附脱苦法、酶法脱苦、固定化细胞脱苦、超临界CO2脱苦、膜技术脱苦、基因工程脱苦。     

柑桔类果汁的脱苦技术

本文简要介绍了脱除柑桔类果汁苦味的一些技术,这些技术包括:代谢脱苦法、屏蔽脱苦法、吸附脱苦法、酶法脱苦、固定化细胞脱苦、超临界CO2脱苦、超临界CO2脱苦法、膜技术脱苦、基因工程脱苦。     

柑桔类果汁苦味物质的脱除研究

柠碱和柚苷是柑桔汁和柑桔其他制品中的主要苦味成分,采用吸附脱苦法、酶脱苦法、β-环糊精脱苦法、乙烯利代谢脱苦法及其他脱苦法可将它们除去,文中还提出了采用综合脱苦法应用于生产实际的观点。     

酶技术在果蔬汁加工业中的应用

酶是生物细胞产生的有催化性的蛋白质。果蔬本身所含有的果胶、纤维素、蛋白质和柚皮苷等是引起果蔬汁混浊、褐变和产生苦味物质等不良现象的主要因素。本文对酶技术在柑桔类果汁脱苦、提高胡萝卜出汁率和增加β-胡萝卜素含量、荔枝汁澄清中的应用及酶法促进风味增强、酶法免疫检测方面的应用作一综合介绍。酶技术的应用不仅克服了传统工艺的缺点,更可有效地分解去除不良大分子物质,且大幅度提高了果蔬汁的品质。一、酶在柑桔类果汁脱苦加工过程中的应用(一) 固定化酶法脱苦机理柑桔类果汁在提炼之后不久就会变苦,这主要是由于柠檬苦素和柚…     

柑桔汁脱苦降酸方法研究进展

"全食"概念日渐为消费者青睐的情况下,柑桔全果制汁是柑桔精深加工的重要方向之一,有效的脱苦降酸工艺对促进柑桔汁生产有重要意义。本文对柑桔汁脱苦的9种方法及降酸的6种方法进行了综述。     

柑橘类果汁脱苦技术研究进展

柚皮苷和类柠檬苦素是柑橘类果汁的主要苦味物质,其存在明显影响了柑橘类果汁的品质。介绍了脱除柑橘类果汁苦味的一些技术：代谢脱苦、吸附脱苦、酶法脱苦、屏蔽法脱苦、分离技术脱苦和基因脱苦等。     

Changes in California Naval Orange Juice during Commercial Debittering

The nutritional and compositional changes (via adulteration screenings) in California navel orange juice during commercial debittering using a hydrophilic absorbent were studied. Both reconstituted and freshly extracted juices were analyzed. There were significant reductions in limonin, citrus oils and pulp. Citrus oils and pulp can be replenished without violation of federal standards of identity. Increases in mineral content resulted from the use of mineral-laden water for reconstituting concentrates before treatment and not from the use of the absorbent.     

膜分离技术在果蔬汁生产中的应用

介绍了膜分离技术在果蔬菜汁澄清，脱苦，浓缩等方面的应用，探索了利用膜联合过程生产高品质质果蔬汁的实际可能性。     

Enzymic debittering of Indian grapefruit (Citrus paradisi) juice

The present work explores the use of enzymes for debittering grapefruit (Citrus paradisi) juice. The debittering process was optimised using a statistical approach. A full factorial design using enzyme concentration (0.25, 0.5 and 1.0 g l^?1), incubation temperature (25, 30 and 40 °C) and time of incubation (1, 2 and 4 h) as variables gave a regression equation that could predict the extent of debittering. The optimum set of conditions recommended is an enzyme concentration of 1 g l^?1 at 40 °C for 4 h. The extent of naringin breakdown achieved under these conditions was 75%. © 2002 Society of Chemical Industry     

Industrial orange juice debittering: Impact on bioactive compounds and nutritional value

The impact of an industrial debittering process (DP) on nutritional and bioactive compounds in orange juice (OJ) was studied. The DP was aimed at removing bitter components in OJ by physical adsorption in a resin. The levels of bioactive compounds (carotenoids, ascorbic acid and phenolics), total antioxidant activity and the colour in the fresh orange juices (non-debittered) and in the debittered counterparts were measured. The results demonstrated that the carotenoid contents were not significantly affected by the treatment. However, the debittered orange juices showed a reduction (p < 0.001) of 26% in ascorbic acid, 32% in hydroxycinnamic acids, 28% of flavones and 41% of flavanones in comparison with the non-treated juices. The antioxidant activity of the hydrophilic fraction (HF) was significantly higher (p < 0.05) in untreated juice than in debittered juices. Some colour parameters (L^∗, a^∗ and h_ab) were also affected. Discriminant analysis revealed that the canonical function related to the levels of HF compounds allowed a 100% correct classifications of the different types of juices.     

Sorption of citrus flavour compounds on XAD‐7HP resin during the debittering of grapefruit juice

Grapefruit juice made from concentrate was debittered using a laboratory‐scale downflow column packed with XAD‐7HP adsorbent resin. Sorption of the bitter principle naringin was analysed by high‐performance liquid chromatography. In addition, the influence of the debittering process on the flavour of the juice was investigated using headspace gas chromatography for the volatile flavour compounds α‐pinene, β‐myrcene, d‐limonene, α‐terpineol and β‐caryophyllene. Kinetic constants were determined for all substances using the Lagergren adsorption model. The debittered juices showed a selective shift in their reduced flavour profile. Reduction of naringin to 51.28% of its initial value led to a decrease in α‐terpineol to 43.05%, whereas the other flavour compounds ranged from 76.27% (β‐myrcene) to 92.76% (β‐caryophyllene). The column flow rate influenced the adsorption of α‐terpineol and naringin. The highest affinity for adsorption was consistently observed for the off‐flavour α‐terpineol, which indicates a promising option for its selective removal from processed juices during debittering.     

Removal of limonin bitterness by treatment of ion exchange and adsorbent resins

This study, the selective removal of limonin bitterness from Washington navel orange juice by batch adsorption to the Amberlite XAD-16HP and Dowex Optipore L285 was investigated and the determination of some compositional changes that occurred with orange juices debittering using adsorption resins were the primary focus. Amberlite XAD-16HP and Dowex Optipore L285 have been successfully used to reduce bitterness to acceptable levels in Washington navel orange juices. Amberlite XAD-16HP does not have any important negative effects on the quality characteristics of orange juices. However, Dowex Optipore L285 reduces the titratable acidity (TA) in the orange juices and so increases the content of soluble solids contents (SSC), pH value, and ratio accordingly.     

Effect of technological processes and storage on flavonoids content and total, cumulative fast-kinetics and cumulative slow-kinetics antiradical activities of citrus juices

Juices from the mandarin Clemenules (Citrus clementina Hort. ex Tan.), the tangor Ortanique (Citrus reticulata Blanco × Citrus sinensis Osb.) and the sweet orange Valencia Late (Citrus sinensis) have been industrially squeezed, pasteurized, concentrated and stored under refrigeration (4 °C) and at room temperature (20 °C). After each process, the flavanone-7-O-glycosides (FGs) and fully methoxylated flavones (FMFs) contents as well as total, cumulative fast-kinetics and cumulative slow-kinetics antiradical activities were determined and compared with those from the corresponding fresh hand-squeezed juices. Neither industrial-squeezing, nor pasteurization or concentration significantly affected FGs and FMFs contents and antiradical activities of assayed juices. Storage caused a slight decrease of the FMFs contents but a significant reduction of both soluble hesperidin contents and cumulative fast-kinetics antiradical activities in all assayed juices. These decreases were dependent on storage temperature. Characteristic values of the varietal characterization parameters, which are derived from the FMFs contents and antiradical activities of fresh hand-squeezed juices, held valid for industrially squeezed, pasteurized and concentrated juices. After storage, however, only the FMFs-derived varietal characterization parameters and cumulative slow-kinetics antiradical activity remained valid for the resulting juices.     

Influence of processing steps and fruit maturity on volatile concentrations in juices from clementine, mandarin, and their hybrids

During growth, ripening, and post-harvest, the quality of fruits can be modified by various stresses. Ample maturation allows prolonged storage and increases the quality of citrus fruits. The eight major volatile compounds in fresh juices from mandarin (Citrus reticulata Blanco var. Willow Leaf), clementine (Citrus reticulata × Citrus sinensis var. Commune), and their six cross-pollinated hybrids were quantified by gas chromatography. Mandarin juice contained the highest volatile concentration (2177.6 ± 110.6 mg L⁻¹), whereas the total aromatic compounds of the hybrid and clementine juices were lower (1060.6 ± 81.6–1724.2 ± 138.5 mg L⁻¹ and 864.8 ± 67.8 mg L⁻¹, respectively). Limonene was the major compound (667.3 ± 53.7–1259.9 ± 98.4 mg L⁻¹) in all juices. We observed significant differences according to the process of juice extraction used (with and without peel). The relative volatile concentration was higher when the juice was extracted with peel, and the juicing process induced differences in the relative volatile concentrations of between 20 and 40%. The levels of volatile compounds in the juice changed according to the degree of fruit maturity. The concentrations of the eight major juice components increased during ripening and until the commercial maturity stage when the juice was obtained from peeled fruits, whereas their concentrations increased until the post-maturation stage when the juices were produced from whole fruits. These two factors determined the contributions of these compounds to the characteristic aromas of Citrus juices.     

毛霉AS3.2778脯氨酸氨肽酶的部分纯化及性质研究

毛霉蛋白酶对大豆蛋白有较高的水解效率并对蛋白水解物有良好的脱苦效果,因此在大豆多肽的制备方面显示出很好的应用前景。为了开发这一蛋白酶系,实验中P采用硫酸铵盐析、离子交换层析、疏水层析及凝胶层析等方法对其进行了分离纯化,从雅致放射毛霉AS3.2778的发酵麸曲中部分纯化得到一氨肽酶组分,并对其性质进行了探讨。纯化的毛霉氨肽酶是一典型的脯氨酸氨肽酶,它对小肽N端的脯氨酸有非常强的水解能力;该氨肽酶在40～45℃、pH6.5有最大催化活性,在30℃以内,pH5.0～8.0有很好的稳定性;在所试验的几种蛋白酶抑制剂中,仅1 mmol/L的苯甲基磺酰氟(PMSF)对毛霉氨肽酶有抑制作用,由此说明纯化的毛霉氨肽酶可能是一种丝氨酸蛋白酶;常见金属离子对该氨肽酶活性的影响不明显;脱苦实验结果表明,纯化的毛霉氨肽酶对于大豆蛋白水解物的苦味有明显的去除效果。