Effect of maturity and processing on bitter compounds in Thai tangerine juice

Optimum conditions of fruit maturity and processing for improved quality of Thai tangerine fruit juice were evaluated. Limonin and naringin components causing bitterness, acidity, total soluble solids and vitamin C were quantified in specified fruit setting and processing conditions.
Higher limonin contents were observed in tangerine fruits harvested early in the season of 1989, whereas naringin contents gradually decreased with maturity. The optimum harvesting time for Thai tangerine fruit which meets the worldwide quality indicators of extracted juice was nine months after fruit set.
Low temperature storage of tangerine juice was only effective in delaying limonin formation if not pasteurized, which resulted in higher limonin concentrations at the start of the storage period. However, naringin concentrations of tangerine juice were not affected by storage conditions and the pasteurization process. Lower extraction pressure of juice resulted in low limonin and naringin concentrations.     

Factors controlling the accumulation of limonin and soluble constituents within orange fruits

A study was made of the differences in the quality and chemical constituents of the juice and albedo from Washington Navel and Valencia Late oranges grown at one orchard location on trifoliata orange and rough lemon rootstocks and harvested over a period of 40 weeks. Variety was the most significant factor in determining limonin contents, with rootstock an important subsidiary factor. Although limonin contents decreased absolutely as the season progressed, the maturity factor was important only in fruit of high initial limonin content. Differences in limonin contents were due to greater accumulation of limonin during fruit development and not to more rapid disappearance of limonin as the season progressed. An unknown factor controlled the distribution of limonin and soluble solids within the fruit, leading to the accumulation of these constituents in the blossom end. This “distribution factor” was so important that the differences in the limonin contents of albedo from the two halves of the same fruit were greater than the differences arising from the rootstock factor. For both limonin and soluble solids contents, the distribution factor operated uniformly throughout the season, irrespective of variety or rootstock. There was a direct relation between the chemical compositions of fruits picked at the same time from trees grown on different rootstocks, suggesting that relatively few picks could provide a basis for comparison of rootstock/scion combinations. The fact that such relations held irrespective of variety indicates an environmental effect on chemical composition which overrides varietal differences, whereas differences in variety and rootstock were more important in determining the physical characteristics of the fruit. Besides providing a basis for selecting fruit to give juice of optimum quality, these findings carry at least equal importance for the new light they throw on the physiological origins of variations in fruit quality.     

Molecular Mass and Solubility Changes in Pectins during Storage of Satsuma Mandarin Fruits (Citrus unshiu Marc.)

Soluble pectins in satsuma mandarin fruits stored at 5°C were investigated by High Performance Gel Filtration chromatography. Pectins isolated from the flavedo, albedo, membranes and juice sacs were separated into four fractions. The hydrochloric acid soluble pectin fraction in each part was the highest and decreased slightly while the water-soluble pectin increased slightly. The avergae molecular weights of the fractionated soluble pectins in juice sacs were nearly constant but those in flavedo, albedo and membranes decreased as storage time increased. The ratios of higher molecular weight of water soluble and ammonium oxalate-soluble pectins in all the four parts and those of hydrochloric acid soluble pectin in flavedo and membranes decreased as ratios of lower molecular weight fractions increased.     

Pectinase and naringinase help to improve juice production and quality from pummelo (Citrus grandis) fruit

Pectinase and naringinase were investigated for improving the production of pummelo juice by increasing the juice yield and eliminating juice bitterness. Compared to a control, the enzymatic treatment significantly (p<0.05) increased the juice yield, soluble pectin and total soluble solid (TSS) contents, and the clarity, while decreasing the concentrations of the bitter chemicals naringin, limonin, and nomilin. A combined processing treatment of peeling and enzymatic hydrolyses using 5U/g of pectinase and 0.4 U/g of naringinase at 50oC for 60 min resulted in a juice yield of 42.3%, a TSS content of 11.4oBx, a titrable acidity (TA) of 0.96%, a vitamin C concentration of 38.4 mg/100 mL, and concentrations of naringin, limonin, and nomilin of 42.4 μg/mL, 33.5 μg/mL, and 13.3 μg/mL, respectively. The enzymatic method was effective and practical for production of high quantity pummelo juice.     

蜂胶涂膜对圆脆鲜枣贮藏保鲜效应

采用蜂胶涂膜剂对圆脆鲜枣进行保鲜处理,通过测定贮藏期鲜枣的腐烂指数、失重率、硬度、可溶性固形物含量、可滴定酸含量、Vc含量及呼吸强度的变化,评价其对圆脆鲜枣的保鲜效果。结果表明,蜂胶涂膜保鲜处理可以显著地降低圆脆鲜枣的失重率和腐烂指数,维持圆脆鲜枣的硬度,抑制可溶性固形物含量、可滴定酸含量和Vc含量的下降及呼吸强度增大,能明显延缓圆脆鲜枣采后的衰老,有效延长圆脆鲜枣的贮藏保鲜期,1.5%蜂胶涂膜处理保鲜效果最佳。     

库尔勒香梨及其芽变和杂交品种（系）果实品质评价因子的选择

采用主成分分析法和聚类分析法对库尔勒香梨及其芽变和杂交的13 个品种（系）果实的主要品质性状 （单果质量、果肉硬度、果形指数、心果比、可溶性固形物含量、可溶性糖含量、可滴定酸含量、石细胞含量、 VC含量、糖酸比、汁液含量）进行了分析,以简化库尔勒香梨及其芽变和杂交品种（系）果实品质的评价指 标。结果表明：不同品种（系）的果实品质存在明显差异,果实石细胞含量和单果质量的变异系数较大,果实汁 液含量变异系数较小,部分品质性状之间存在简单的相关性;主成分分析提取出5 个主成分,累计方差贡献率为 88.964 5%,可以在一定程度上概括这些性状的总体信息量;依据不同品种（系）的主成分得分,筛选出的5 个代 表性的品种（系）分别为84-1-1、84-1-15、新梨9号、新梨8号、84-4-72。经聚类分析,可将库尔勒香梨及其芽变和 杂交品种（系）果实品质评价指标简化为单果质量、果形指数、石细胞含量、可溶性固形物含量和汁液含量5 个主 要指标。综合运用主成分分析和聚类分析方法,可以简化库尔勒香梨及其芽变和杂交品种（系）果实品质的评价指 标,有助于库尔勒香梨优良果实性状品种的评价与筛选。     

荔枝汁结冰-解冻浓缩过程中品质的变化规律

以灭菌后的荔枝汁为原料,采用结冰-解冻浓缩工艺将其浓缩,研究了浓缩过程对荔枝汁的可溶性固形物含量、褐变度和可滴定酸度的影响,并运用气相色谱-质谱联用法对浓缩过程中的荔枝汁的挥发性风味物质进行测定,探讨其品质的变化规律。结果表明:荔枝汁中可溶性固形物的含量和褐变度随解冻所得的荔枝汁总体积的增加而逐渐降低;浓缩过程中,挥发性风味物质的相对含量的变化趋势因物质类型不同而不尽相同。综合考虑理化指标与风味物质的变化规律,可将解冻过程中荔枝汁总体积的40%(v/v)处选定为浓缩汁与剩余液的分界点,得到的浓缩汁中风味较高。     

Reduction of bitterness and acidity in grapefruit juice by adsorptive processes

By choosing an appropriate adsorbent, the bitter principles (naringin and limonin) and titratable acids could be removed from grapefruit juice in varying combinations. For example, Amberlite XAD-7 removed about 63% naringin, 85% limonin and 3% titratable acids and Deacidite-FFIP removed about 20% naringin, 8% limonin and 23% titratable acids when contacted for 1 h with grapefruit juice at the rate of 20 g (dry wt) of adsorbent per litre of juice. Such treatments, applied consecutively, would eliminate excessive bitterness and acidity from juices containing up to 2 g naringin and 36 mg limonin litre^?1 and with a total soluble solids:titratable acid ratio of < 6. The adsorbents are readily available, may be used as supplied and can be reactivated simply and economically; some of them have already been approved for use with foods, and such approval seems possible for the others.     

Multiple Forms of Pectinmethylesterase from Citrus Peel and Their Effects on Juice Cloud Stability

Heparin chromatography of a dialysis supernatant fraction from total salt extractable proteins of Citrus sinensis (L.) Osb. var. Valencia fruit peel (flavedo plus albedo) resolved four peaks of pectinmethylesterase activity (PME 1–4). One of these was thermally tolerant (PME 3). Binding to concanavalin A suggested PME 3 was a glycoprotein. At 30°C and 5 U - mL1 PME 1, 2 and 3 destabilized the cloud of pasteurized FCOJ within 10 days. PME 1 caused the most rapid cloud loss (3d), followed by PME 3 and PME 2. PME 4 had no effect on juice cloud during this time period. At 4°C PME 3 caused the most rapid cloud loss (3d), followed by PME 1 (14d) and PME 2 (>14d). PME 4 had no effect on juice cloud stability after 10 days at 30°C or 14 days at 4°C.     

Maturity and ripening effects on chemical and sensory properties of apple juice

The effects of harvest maturity and ripening on the chemical composition and sensory characteristics of ‘McIntosh’ and ‘Spartan’ apple juice were evaluated. Juice was extracted from fruit harvested at seven weekly intervals beginning 3–4 weeks before commercial harvest and from fruit held in air storage (1°C) for 1 to 3 months. Internal ethylene concentration and starch index were used as maturity indices. Principal component analysis of juice data (pH. titratable acidity, organic acids, soluble solids, sugars, phenols, turbidity, and Hunterlab colour) showed a distinctive maturity effect on the characteristics of juice extracted from fruit immediately after harvest or after storage. Triangle testing showed aroma and flavour differences in both ‘McIntosh’ and ‘Spartan’ to be first discernable when ethylene was first detected (internal ethylene concentration ≥ 0.1 μl litre^?1) and starch hydrolysis evident (starch index 3.0–5.0 for ‘McIntosh’, 1.5–3.0 for ‘Spartan’), or after 2–3 months of air storage. Sensory profiling of fruity aroma, total aroma, fruit flavour by mouth, sweetness, and sourness in the juices showed increased fruitiness and sweetness and decreased sourness with advancing maturity.     

Limonin Monolactone, the Nonbitter Precursor Responsible for Delayed Bitterness in Certain Citrus Juices

SUMMARY– Tissues of early-season navel oranges and grapefruit were found by paper electrophoretic procedures to contain a nonbitter precursor of limonin, but no significant amounts of limonin. Limonin is the intensely bitter triterpenoid dilactone responsible for the bitterness which develops in certain navel orange juices on standing. The nonbitter precursor was identified as limonin monolactone by comparison with the authentic compound prepared by partial hydrolysis of limonin and by acid-catalyzed conversion into limonin. Limonin monolactone is stable in the tissues of the intact fruit (which are not bitter) because it is apparently not in direct contact with the acidic juice. It is slowly converted into limonin (and the juice becomes bitter) when the fruit tissues come in contact with the juice, after the juice is expressed from the fruit. Limonin monolactone was not detected in late-season navel oranges or grapefruit. This agrees with the fact that juice made from these fruits does not contain limonin. Work is in progress to determine whether the naturally occurring limonin monolactone is the A-ring monolactone, the D-ring monolactone, or a mixture of the two.     

Process development for stabilization of sugarcane juice using response surface methodology

Sugarcane juice is a very popular drink in India and other Asian countries, where sugarcane is an important crop. Since sugarcane juice spoils very quickly and there is a lack of research in this area, no commercialized sugarcane juices are available in India. Here, stabilized sugarcane juice was developed using response surface methodology. Total soluble solids, reducing sugar, total sugar, polyphenol oxidase activity, ascorbic acid, pH, optical density, transmittance, titrable acidity, microbiological properties, and sensory scores of the stabilized juice were evaluated using a Box–Behnken design. The composition was optimized and the sugarcane drink was further processed using blending and hot filling techniques. The processed juice was hot-filled into glass bottles under aseptic conditions. The predicted shelf life of the processed sugarcane juice was 3 months at 18 °C and 6 months at 10 °C.     

云南酸木瓜风味果醋的研制

以云南酸木瓜为主要原料,添加普洱茶汤及新鲜咖啡汁进行液态发酵,酿制酸木瓜复合风味果醋。通过对可溶性固形物含量和总酸度的测定以及感官评分验证了试验的可行性,并在此基础上进行正交试验,确定了云南酸木瓜风味果醋的最佳配比:以酸木瓜为底料,添加普洱茶汤25%、新鲜咖啡汁10%、白砂糖19.5%。     

Reduction of Bitterness and Tartness in Grapefruit Juice with Florisil

Treatment of commercial grapefruit juice with Florisil (activated magnesium silicate) simultaneously reduced the content of citric acid and the bitter compounds limonin and naringin. Ascorbic acid concentration and °Brix (total soluble solids) were not altered by the Florisil treatment. Experienced taste panelists were able to differentiate between the nontreated and Florisil-treated juice on the basis of bitterness and tartness (acidity). The panelists indicated a preference for the Florisil-treated juice.     

龙眼核精油的体外抗氧化活性及其保鲜效果

本项目研究龙眼核精油体外抗氧化性及常温保鲜效果,以有机溶剂正己烷提取龙眼核精油,测定精油对1,1-二苯基-2-苦肼基自由基(DPPH·)、羟基自由基(·OH)及亚硝酸钠(NaNO_2)的清除能力,以龙眼果肉颜色、果皮褐变指数、失重率、可溶性固形物、可滴定酸含量等生理指标变化作为保鲜效果的评判标准。结果表明:龙眼核精油对DPPH·、·OH及NaNO_2均有一定清除作用,IC_(50)分别为11.04、4.58、0.12 mg/mL,在试验浓度范围内呈一定量效关系;精油可降低龙眼果皮褐变指数及失重率上升速度;可溶性固形物含量变化起伏小;贮藏前期,可滴定酸含量变化缓慢,后期上升较快;精油处理组与空白对照组间差异不显著(p0.05),龙眼核精油对龙眼果实不具备明显保鲜效果;精油浓度过大会对龙眼果实产生不同程度的药害。     

Purification of naringin and neohesperidin from Huyou (Citrus changshanensis) fruit and their effects on glucose consumption in human HepG2 cells

Huyou (Citrus changshanensis) is rich in naringin and neohesperidin, which are natural flavanone glycosides with a range of biological activities. Among the different fruit parts, i.e. flavedo, albedo, segment membrane (SM), and juice sacs (JS), albedo showed the highest contents of both compounds, with 27.00 and 19.09mg/g DW for naringin and neohesperidin, respectively. Efficient simultaneous purification of naringin and neohesperidin from Huyou albedo was established by the combination of macroporous D101 resin chromatography and high-speed counter-current chromatography (HSCCC). Purified naringin and neohesperidin were identified by both HPLC and LC-MS, and their effects on glucose consumption were investigated in HepG2 cells. Cells treated with naringin and neohesperidin showed increased consumption of glucose, and this was associated with increased phosphorylation of AMP-activated protein kinase (AMPK). Therefore, naringin and neohesperidin from Huyou may act as potential hypoglycaemic agents through regulation of glucose metabolism.     

Enzymatic added extraction and clarification of fruit juices–A review

Enzymatic treatment for juice extraction is most commonly used now a days. The enzymatic process is claimed to offer a number of advantages over mechanical-thermal comminution of several fruit pulps. Enzymes are an integral component of modern fruit juice manufacturing and are highly suitable for optimizing processes. Their main purposes are: increase extraction of juice from raw material, increase processing efficiency (pressing, solid settling or removal), and generate a final product that is clear and visually attractive. Juice extraction can be done by using various mechanical processes, which may be achieved through diffusion extraction, decanter centrifuge, screw type juice extractor, fruit pulper and by different types of presses. Enzymatic treatment prior to mechanical extraction significantly improves juice recovery compared to any other extraction process. Enzymatic hydrolysis of the cell walls increases the extraction yield, reducing sugars, soluble dry matter content and galacturonic acid content and titrable acidity of the products. Enzymatic degradation of the biomaterial depends upon the type of enzyme, incubation time, incubation temperature, enzyme concentration, agitation, pH and use of different enzyme combinations. We can conclude from the technical literature that use of the enzymes i.e. cellulases, pectinases, amylases and combination of these enzymes can give better juice yield with superior quality of the fruit juice. Pectinase enzyme can give maximum juice yield i.e. 92.4% at 360 minutes incubation time, 37°C incubation temperature and 5 mg/100 g of enzyme concentration. Whereas the combination of two enzymes i.e. pectin methyl esterase (PME) and polygalacturonase (PG) at 120 minutes of incubation time, 50°C of incubation temperature and 0.05 mg/100 gm of enzymatic concentration can give the maximum yield of 96.8% for plum fruits. This paper discusses the use of enzymes in fruit juice production focusing on the juice recovery, clarity and effect of the particular enzyme on the biochemical properties of the fruit juices.     

Important flavonoids and limonin in selected Thai citrus residues

The distributions of important flavonoids and limonin in selected Thai citrus residues were investigated in this study. The residues of interest were peels of pomelo (Citrus grandis (L.) Osbeck cv. Kao Yai and cv. Kao Nampheung), residues after juice extraction of tangerine (Citrus reticulata Blanco cv. Sainamphueng and cv. Bangmod) and peels and residues after juice extraction of kaffir lime (Citrus hystrix DC). Flavonoids were characterized and quantified in terms of flavanones, i.e., naringin and hesperidin, and polymethoxyflavones (PMFs), i.e., nobiletin, sinensetin and tangeretin. Naringin was a dominant flavanone in polmelo peels. Three PMFs were found in all samples with varying contents. Comparing the samples, residues from tangerine cv. Bangmod exhibited the highest value of each PMFs. Limonin was present in small amounts in pomelo peels and residues after juice extraction of tangerine and kaffir lime. All samples were good sources of dietary fibre, with a total dietary fibre content of more than 60 g/100 g on a dry weight basis with high proportion of soluble dietary fibre.     

常山胡柚果实不同部位有效成分含量及其 抗氧化活性比较

将常山胡柚全果分为白皮层、油胞层、籽、果渣和果汁5 部分,除果汁外其余4 部分烘干后用70%乙醇溶液热回流提取制备不同部位的醇提物,分别测定醇提物总黄酮和总酚含量,并采用4 种自由基评价体系比较其抗氧化活性的差异。研究表明,常山胡柚不同部位醇提物中总黄酮含量的高低依次为：油胞层（3.78%）＞白皮层（2.38%）＞籽（1.67%）＞果渣（0.77%）,总酚含量最高也为油胞层（21.30%）,最低为果渣（1.73%）;油胞层清除1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、O2－·和·OH的效果最佳,IC50值分别为0.37、0.24 mg/mL和1.31 mg/mL;而清除ABTS＋·效果最好的则是白皮层（IC50值为0.015 mg/mL）。同时,测得胡柚果汁的总黄酮和总酚含量分别为0.021%和0.19%,清除DPPH自由基、ABTS＋·、·OH和O2－·的IC50值分别为8.55、18.97、35.17 mg/mL和23.30 mg/mL。研究表明,胡柚果皮含有丰富的强抗氧化成分,且其质量约占全果的1/3,对其进行深入研究和综合开发是常山胡柚这一宝贵资源高值化利用过程中不可或缺的环节。     

柑橘果实中抗癌活性物质的研究现状和前景

从柑橘果实中 (幼果、果皮、果汁、种子 )提取分离具有抗癌药理作用的活性物质 ,在国内外受到关注。研究表明 ,至少在 3大类物质中即类胡萝卜素 (carotenoid)、黄酮类化合物(flavonids)及柠檬苦素类 (limonoids)的抗癌作用已被评价 ,其中从上述 3类物质中分离获得并鉴定的番茄红素 (lycopene)、柑橘苷配基 (naringenin)和柠檬苦素 (limonin)等 9种活性物质具有抗癌作用 ,β 胡萝卜素 (β carotene)可能对艾滋病有预防作用 ,更支持了上述的评价。