不溶性壳聚糖处理后苹果汁主要营养素的变化研究

研究苹果汁经不溶性壳聚糖处理后主要营养素的变化。苹果汁经不溶性壳聚糖的脱色和澄清处理后,除了Vc含量下降10%以外,其他主要营养成分几乎没有变化,果汁的色值和透光度均达到国际贸易标准的要求。由此可见,不溶性壳聚糖用于苹果汁的脱色和澄清,既可以保证果汁的品质,也不会对主要营养成分造成损失,可以用于苹果汁的工业化生产。     

用于苹果法吸附实验的不溶性壳聚糖制备工艺的研究

研究了用于苹果汁吸附实验的不溶性壳聚糖的制备工艺.不溶性壳聚糖的制备工艺条件为:脱乙酰处理时NaOH的质量分数为35%、50℃、6h.对不溶性壳聚糖的吸附性能、再生性能和质量标准进行了研究,制备的不溶性壳聚糖符合国家标准的要求,可以多次再生使用,不易造成二次污染,且具有良好的机械强度,适合用做苹果汁脱色和澄清的吸附材料.     

Detection of fruit juice adulteration in apple and pear juice

A method has been developed to detect the adulteration of pear juice with apples and apple juice with pears. In different varieties of apples and pears and in several commercial juices the flavonoids were examined by HPLC with respect to their quality and quantity. The chalcones phloretin glucoside and phloretin xyloglucoside are typical compounds found in apples (detection limit 7 ng). They are suitable indicators for detecting adulteration of pear juice with apples. Isohamnetin glucoside cannot be detected in apples (detection limit 10 ng), but can be used to detect pears in apple juice. The extract or juice was purified with the aid of a polyamide column. The evaporated eluate of methanol was analysed by HPLC (gradient: acetonitrile/1% acetic acid). An RP-18 column and a UV-detector were used. Additionally, the UV spectra of the compounds indicating an adulteration were recorded by a diode array detector.     

Evaluation of the sensory properties of irradiated apple juice concentrate

Summary Apple juice concentrate with or without addition of aroma essence was irradiated with doses of 0.5–2.0 kGy. The irradiated samples and nonirradiated control were evaluated for colour, clarity, odour and taste. The trained eight-member panel of judges examined the concentrate using a 10-cm long unstructured graphical scale method. In addition, the intensity of some odour and sensory profiles were obtained. Slight sensory differences could be noticed between the irradiated and nonirradiated samples, these differences were more pronounced in the concentrate irradiated with the dose of 2.0 kGy. Sensory evaluation of the colour confirmed the brightening of the irradiated samples which was also observed by spectrophotometric measurements. The clarity of the concentrate was not influenced by irradiation.

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Bestimmung der sensorischen Eigenschaften des bestrahlten Apfelsaftkonzentrates

Zusammenfassung Das Apfelsaftkonzentrat mit oder ohne Zugabe von Aromaessenz wurde mit Dosen von 0,5 bis 2,0 kGy bestrahlt. Die bestrahlten Proben und die nicht bestrahlte Kontrollprobe wurden auf Färbung, Klarheit, Geruch und Geschmack untersucht. Das Apfelsaftkonzentrat wurde durch acht erfahrene Personen unter Verwendung einer 10 cm langen graphischen Skala geprüft. Zusätzlich wurde die Intensität der Geruchsund Geschmacksprofile geschätzt. Es wurden geringfügige sensorische Unterschiede zwischen bestrahlten und nicht bestrahlten Proben gefunden. Die Unterschiede waren stärker wahrnehmbar nach der Bestrahlung mit 2,0 kGy. Sensorische Untersuchung der Färbung bestätigte die Aufhellung der bestrahlten Proben, die ebenfalls bei den spektrophotometrischen Messungen beobachtet wurde. Die Bestrahlung hatte keine Wirkung auf die Klarheit des Konzentrates.

     

苹果汁的掺假鉴定

从糖、有机酸、氨基酸、稳定性同位素、类黄酮、阳离子及光谱学等方面全面探讨了真假苹果汁的鉴定方法，为苹果汁加工业提出了一系列行之有效的鉴定掺假方法。     

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.     

浓缩苹果清汁色值下降问题的研究

<正> 浓缩苹果清汁因原料种类、加工工艺和保存条件不同,而造成果汁色值下降速度不同。有效控制色值下降,防止果汁的营养损失是关键。 色值下降机理 果汁的色素主要是酚类色素,如花青素、花黄素和鞣质等,这些色素都极不稳定。由于苹果在破碎过程中,作为呼吸传递的酚醌氧化还原系统受到破环,酚羟基氧化为醌型结构,醌大量聚集,醌一旦形成后会引起两种情况:一是羟醌自动聚合,随聚合程度增大,由红变褐,最后形成褐黑色素物质;二是醌和氨基酸发生非醌的缩合反应,形成     

Patulin reduction in apple juice from concentrate by UV radiation and comparison of kinetic degradation models between apple juice and apple cider

Patulin, a mycotoxin produced by several genera of fungi, including Byssochlamys, Aspergillus, and Penicillium, has been an important concern in apple cider and apple juice due to its toxicity and health consequences. In this study, the effects of UV on the patulin level, physical and chemical properties, and sensory attributes in apple juice from concentrate were investigated. Kinetic modeling of patulin reduction by UV radiation in apple juice from concentrate was calculated and compared with the degradation rate observed previously in apple cider. From an initial patulin contamination of approximately 1,000 ppb (μg/liter), the UV exposure, ranging from 14.2 mJ/cm(2) (one pass) to 99.4 mJ/cm(2) (seven passes), was successful in reducing patulin levels by 72.57% ± 2.76% to 5.14% ± 0.70%, respectively. Patulin reduction by UV radiation followed first-order kinetic modeling in a fashion similar to first-order microbial inactivation. An exponential correlation between UV exposure and the percentage of patulin remaining was observed, giving an r(2) value of 0.9950. Apple juice was repeatedly exposed to 14.2 mJ/cm(2) for each treatment, and patulin levels were significantly decreased when compared with the level obtained with the previous UV exposure treatment. While there were no significant differences in the percentages of titratable acidity and ascorbic acid (P > 0.05), there were minor yet random sampling differences in pH and degrees Brix (1 °Brix is 1 g of sucrose in 100 g of solution; the °Brix represents the soluble solids content of the solution as percentage by weight [%, wt/wt]) (P ≤ 0.05). A significant difference (P ≤ 0.05) in sensory perception for the finished apple juice was detected between the control and the full seven-pass UV radiation treatment using an experienced consumer panel and a triangle test. Patulin reduction by UV radiation from both the current study and a previous study involving apple cider was compared, which showed that both matrices strongly fit a first-order kinetic degradation model. However, the kinetic constant for degradation in apple juice was approximately 5.5 times greater than that observed in an apple cider matrix.     

Co-products of black-currant and apple juice production: Hydration properties and polysaccharide composition

The sugar composition in cell walls of apple and black currant pomaces was investigated with or without solvent extraction. Extraction of polyphenols by solvents changed the sugar composition of cell walls by increasing the alcohol insoluble solids (AIS) contents and increasing glucose content. Water binding capacity was increased by the ethanol extractions, but decreased again after acetone treatments. The enzyme treatments used for juice extraction increased the swelling capacity but decreased the water binding capacity, probably by loosening the cell wall structure. They resulted in decreased degrees of methylation. Pectin extractability of black currant pomaces differed between the commercial pomace (higher Water Soluble Pectins fraction and Chelator Soluble Pectins fraction), and the experimental pomaces (higher Diluted Alkali Soluble Pectins fraction).     

壳聚糖在果汁澄清中的应用

壳聚糖可由海洋生物虾、蟹的外壳中提取甲壳素经过脱乙酰基得到,是迄今为止发现的唯一的阳离子动物纤维和碱性多糖。作为天然澄清剂,壳聚糖属于阳性,能与果汁中属阴性的胶体物质产生静电作用,对胶体物质有很强的凝集力,因此可以使混浊的果汁变的澄清。     

Ascorbic acid degradation in a model apple juice system and in apple juice during ultraviolet processing and storage

Ultraviolet radiation induced degradation of ascorbic acid in a model apple juice system and in apple juice was studied using a collimated beam batch UV reactor. In the model system, ascorbic acid degradation was more rapid at higher dose levels and the reaction accelerated with increasing exposure time. Ascorbic acid degradation significantly (P < 0.05) increased as the pH was raised from 2.4 to 5.5, although no difference was observed between 2.4 and 3.3. Increasing malic acid concentration between 0.1 and 1%, increased ascorbic acid degradation (P < 0.05) although there was no difference between 0.5 and 1.0%. Solution absorbance, varied by addition of tannic acid, decreased ascorbic acid degradation with increasing concentration due to absorption of UV radiation. Fructose at levels found in apple juice significantly increased ascorbic acid degradation while glucose and sucrose did not. Factors identified that accelerate ascorbic acid degradation may at least partially explain why ascorbic acid degradation occurred more rapidly in UV-treated apple juice than in the 0.5% malic acid model system. Ascorbic acid degradation continued after UV treatments during dark storage. Storage decreases were faster at higher initial UV dose levels and higher storage temperature. PRACTICAL APPLICATION: The present study shows the effect of UV processing on ascorbic acid, a key vitamin found in many fruit juices. Process developers and researchers can use this study as a model for designing experiments to identify factors that influence the stability of vitamin C and other bioactive compounds during UV processing.     

Rheological behaviour of apple juice and pear juice and their concentrates

This paper reports the rheological behaviour of apple juice and pear juice. The effect of temperature on this behaviour for concentrated apple juice and pear juice of 71°Brix and 70°Brix, respectively, is examined and equations are given to describe the change in viscosity with temperature within the temperature range 5–60°C. The rheology of apple juice and pear juice of different soluble solids concentrations at 25°C is likewise reported with equations to relate the change in viscosity with concentration within the concentration range studied. In all these cases these juices are Newtonian in behaviour.     

Flavour losses in apple juice manufacture

Flavour losses occurring in apple juice manufacture were investigated by gas chromatography and sensory analysis in two factories A and B using different technologies and equipment. Samples were taken at different intervals during the processing season from the raw material, the pressed juice, the clarified and filtered juice, the apple juice concentrate and the apple flavour concentrate produced in plant A. The chromatograms of the pressed juice showed changes in volatile composition as compared to the raw material: the number of components was slightly reduced, although some new components could be detected, probably owing to enzymatic processes. The enzyme preparation and method used for clarification did not affect volatile composition to the extent expected. The volatile abstracting effect of vacuum evaporation for flavour recovery as performed in plant A seems to be compensated by flavour formation from precursors during pectolytic enzyme treatment. The greatest losses in both factories were encountered during evaporation concentration of the clarified and filtered juice. Chromatographically established volatile composition was distinctly different in the concentrated apple juice samples from the two plants, however, this difference was perceived by the sensory test panel only towards the end of the processing season. The apple flavour concentrate contained less than half of the volatile components present in the raw material. The gas chromatograms of the flavour concentrates produced at different times did not reflect the fluctuations observed in the volatile composition of the raw material and the intermediate and end products, however, sensory tests showed the samples from the beginning of the processing season to be superior to those from its end.     

Antiulcerative properties of crude polyphenols and juice of apple,and Chinese quince extracts

Effects of Chinese quince extract, apple juice, semi-purified phenolics and soluble pectin from these fruits on ethanol-induced gastric ulcers in rats were investigated. In rats given Chinese quince extract or apple juice, ulcer induction was strongly suppressed, and the effect was stronger for Chinese quince extract than for apple juice. Myeloperoxidase activity in gastric mucosa showed a similar tendency. The DPPH radical scavenging activity and total phenolic content were 4 times higher in Chinese quince extract than in apple juice. Semi-purified phenolics from both fruits strongly suppressed ulcer induction at doses of 5–10 mg; however, a 20 mg dose of apple phenolics showed a pro-ulcerative effect. The soluble pectin fraction also showed moderate activity. These results suggest that phenolic compounds are responsible for antiulcerative activity of Chinese quince extract and apple juice, and that concentration may be an important factor in the case of apple phenolics.     

鲜榨苹果汁与浓缩苹果汁酿酒特性的比较

以苹果鲜榨汁和浓缩汁为原料,分别通过添加蔗糖和稀释的方式使发酵起始糖度为200g/L进行酒精发酵。对发酵产品的常规理化指标和总酚,总类黄酮以及黄烷醇含量进行测定,并对发酵产品进行感官鉴评。实验结果表明:稀释浓缩汁和鲜榨果汁酒样总酸含量分别为2.6g/L和3.2g/L。鲜榨果汁酒样总酚含量、总类黄酮以及黄烷醇含量均高于稀释浓缩汁酒样。两种酒各具特色,鲜榨汁酒样果香浓郁,稀释浓缩汁酒样酒香醇厚。      

Free and bound patulin in cloudy apple juice

During validation of an HPLC-UV method for patulin analysis, a time and concentration dependent recovery of patulin was observed. Spiked cloudy apple juice was analysed on successive days, which resulted in recoveries on day 3 which were up to 20% lower than on day 1. This reduction was caused by an interaction between patulin and the solid parts of cloudy apple juice. Since these solid parts are richer in proteins compared to the liquid phase of cloudy apple juice, and the binding of patulin to proteins has been described in the literature, patulin will most probably interact with the proteins in the solid parts. As a consequence, up to 20% of the present patulin is bound and not detected during HPLC-UV analysis, which can lead to an underestimation on toxicological level.     

苹果汁和桃汁种类特异性PCR检测方法的研究

本文采用苹果属过敏原蛋白的mal d 4.02基因,桃属微卫星标记MA023a分别作为苹果汁和桃汁特异性引物,并以植物高度保守的叶绿体AccD基因作为内标物,利用PCR检测方法对两种果汁进行种属鉴定。结果表明,特异性PCR检测方法可以准确的对苹果和桃产品进行种属鉴定,苹果、桃属特异性PCR检测方法的最低检测限分别为5、10ng/μL,此方法能快速、准确对苹果汁和桃汁种类进行定性鉴定和掺假检测。      

Effect of heat treatment and evaporation on patulin and some other properties of apple juice

Patulin, hydroxymethylfurfural (HMF), colour and clarity values of 20 apple juice samples with different Brix contents were determined after heat treatment (90 and 100 °C for 5, 10, 15 and 20 min under atmospheric pressure) and evaporation (70 and 80 °C for 5, 10, 15 and 20 min) processes. As the heating and evaporation times increased, the concentration of patulin in the apple juice samples decreased. The 90 and 100 °C heat treatments resulted in reductions in patulin concentration of 18.81 and 25.99% respectively after 20 min; the corresponding values were 9.40 and 14.06% for 70 and 80 °C evaporation respectively. The increase in HMF was higher with heat treatment than with evaporation. Evaporation decreased the colour values of the samples, whereas heat treatment increased them. © 2003 Society of Chemical Industry     

High-pressure treatment of cloudy apple juice

A factorial design with four factors (pressure, holding time, temperature and waiting period between crushing of apple and high-pressure (HP) treatment) was built up to study the effect of HP treatment on pectin methylesterase activity (PME, EC 3.1.1.11) in cloudy apple juice. PME activity was measured by the methanol release during the storage of samples at 4 °C for 1 month. Only the holding time of the treatment and three interactions between factors (holding time×temperature, pressure×waiting and holding time×waiting) had significant effects on the PME level. Increasing the pressure or the holding time at moderate temperatures (15-40 °C) increased the activity. PME purified from apple was pressure stable in the range 100-600 MPa at 25 °C. The soluble pectin content was not changed after HP treatment. The particles size increased with the temperature reached during the treatment, in agreement with a diffusion-limited-aggregation model but were independent of pressure and holding time. In a separate experiment we found a positive correlation between the PME activity and the residual content of the catechins suggesting that polyphenoloxidase (PPO, EC 1.14.18.1) and oxidized polyphenols play a role in the PME activity level after HP treatment.     

苹果汁中果汁含量测定方法研究

原果汁含量是苹果汁及其饮料的主要质量指标,也是判定苹果汁是否掺假的重要依据。通过对6个产地5个品种自制苹果汁的部分组分进行研究,找出与苹果汁含量有良好定量关系的特征性组分——钾、总磷和氨基酸态氮,以它们作为苹果汁含量测定参数,并且确定了各组分的标准值、权值分配方案及异常数据修正原则。据此,推导出苹果汁含量计算公式;同时按此法对自制的苹果汁和市售的6个品牌的苹果汁进行了果汁含量测定,进一步验证了此方法的可行性。此方法可用于苹果汁果汁含量测定或用于鉴别苹果汁的真伪。