From Apple to Juice—The Fate of Polyphenolic Compounds

Apples are a rich source of polyphenolic compounds and significantly contribute to the antioxidants in our diet. Apple variety affects the levels of those compounds; concentration can also be reduced during processing, especially juice production. These compounds have been linked with numerous health benefits. Reviews on the apple polyphenolic compounds and their health benefits exist; however, a review on maximizing the retention of the polyphenolic compounds in apple juice has not been compiled. Therefore, the purpose of this paper is to review the literature regarding apple polyphenolic compounds and the effects of processing techniques on their concentration in apple juice.     

加工过程中添加剂对苹果汁非酶褐变的影响

加工过程中添加剂对苹果汁非酶褐变的影响很大。金帅苹果在破碎时加入EDTA－Na2、柠檬酸和CaCl2可减轻非酶褐变程度,最优化组合为0．03mol/L CaCl2 0.003mol/L EDTA-Na2 0.005mol/L柠檬酸（A420值为0．100）;而对于富士苹果其最优化组合为0．06mol/L CaCl2 0.006mol/L EDTA-Na2 0.005mol/L柠檬酸（A420值为0．075）;在富士苹果破碎时加入NaHSO3、Cys和VC亦可减轻非酶褐变程度,其最优化组合为0．001mol/LNaHSO3 380mg/mlCys 0.006mol/L VC(A420值为0．231）。     

Portable, low-cost equipment for small-scale fruit juice processing

Simple, low-cost portable equipment to extract citrus juice, and pasteurize it and other fruit juices by passing through a coil of stainless steel tube in boiling water was designed, constructed and tested. Temperature reached was varied by altering the hydrostatic feed height, and the product was directly hot-bottled and capped. Pasteurization was microbiologically effective, and had little effect on ascorbic acid, furfural and colour of freshly prepared pineapple orange, Valencia orange and apple juices, and an orange squash drink, and only the expected changes occurred on storage at 21°C for periods up to 6 months, although with no indication of microbial activity. Taste panel ratings showed a loss of liking for treated orange juice, but not for apple. The equipment is suitable for improved utilization of crops by community technology in less-developed areas.     

Effect of apple cultivar and enzyme treatment on phenolic compounds content during clear apple juice production

The aim of the investigation was evaluation of phenolic compounds content, measured by HPLC method at selected stages of clear apple juice production with pectolytic mash enzymation from ‘Shampion’ and ‘Idared’ apples. Sum of phenolic compounds in ‘Shampion’ mash was significantly higher than in ‘Idared’ mash, 520 and 352 mg kg^?1, respectively. Enzymation of ‘Idared’ mash resulted in a higher phenolic compounds decrease compared to ‘Shampion’, 23% and 14% respectively. Sum of phenolics in juices from ‘Shampion’ for Panzym at 50 °C (366 mg kg^?1) was significantly higher than in juices from ‘Shampion’ for Rohapect at 20 °C and ‘Idared’ for Panzym at 50 °C (256 and 234 mg kg^?1, respectively). The lowest phenolics (95 mg kg^?1) was in juices from ‘Idared’ for Rohapect at 20 °C. There was a positive correlation (R² = 0.933) between phenolics content and antioxidant activity of juices (ABTS^?+). In general, enzymation at 50 °C with Panzym lead to a higher content of the phenolic compounds in juices compared to Rohapect at 20 °C.     

苹果汁芳香物质的研究——传统蒸发、精馏工艺回收苹果汁芳香物质

为了评价用于芳香物质回收和果汁浓缩的蒸发、精馏设备的合理性及完善工艺,利用三效蒸发、精馏试验设备(PAF 53S,Unipektin)对苹果汁芳香物回收进行了研究。结果表明,芳香物在分离、回收过程中有相当部分被损失掉,回收率只有33.84％。这主要取决于芳香物的冷凝回收体系。醇类物质可以经过表面冷凝器凝结下来,而大部分酯和醛则要经过气体冷却器或真空泵循环系统沉降下来。精馏过程中芳香物在精馏塔内的浓度是非常低的,这一结果表明,对于苹果汁芳香物的回收可以不应用精馏塔这一昂贵设备。使用气体淋洗器增加了芳香物的损失,或者不使用,或者改变其结构。芳香物通过精馏塔水和冷凝水的损失可以忽略不计。     

浓缩苹果汁酶促褐变及其控制

酶促褐变是引起苹果浓缩汁色值降低、品质劣变的主要原因之一 ,本文介绍了浓缩苹果汁酶促褐变的三个必要生化条件 :酚类物质、多酚氧化酶 (PPO)和氧气 ,并综述了浓缩苹果汁生产中酶促褐变的控制方法 ,如加热钝化酶、调节pH值、添加酶或底物的抑制剂、使用膜技术、添加漆酶等 ,均能有效控制浓缩苹果汁的酶促褐变 ,提高果汁的品质     

What are domestic apples worth? Hedonic responses and sensory information as drivers of willingness to pay

The effects of written information of key sensory characteristics of apple cultivars on hedonic ratings and willingness to pay (WTP) were measured in an experimental auction. Participants (n = 118, 95F, 23M, mean age 37 y.) rated, in three subsequent rounds, pleasantness and WTP based on (1) appearance only (n = 25), (2) appearance, written information and tasting (n = 44), or (3) appearance, tasting and written information (n = 49). Four domestic cultivars were described as medium sour and crispy (‘Amorosa’), sour and medium crispy (‘Konsta’), medium sweet and medium crispy (‘Lobo’) and sweet and medium crispy (‘Tobias’). The differences between the cultivars in pleasantness and WTP were minimal when the evaluation was based on appearance only. The effect of tasting after visual inspection was positive in three cultivars and negative in one (‘Konsta’). Written information after tasting did not affect pleasantness or WTP. For one cultivar (‘Tobias’), information given before tasting created expectations that were not fulfilled, thus tasting decreased hedonic ratings and WTP. Mean WTP was 2.36 euro/kg. When pleasantness increased by one point, WTP increased by 0.31–0.45 euro/kg. Regression models showed that pleasantness explained 38–55% of WTP. Respondents who reported consuming domestic apples more often than once a week had 0.52–0.74 euro/kg higher WTP than those who consumed them less frequently, suggesting that familiarity with the product increases WTP. Results indicate that both written information and tasting contribute to the ratings of pleasantness and WTP.     

苹果汁复合澄清法和壳聚糖澄清法的优化研究

研究了果胶酶复合澄清法和壳聚糖澄清法对苹果汁的澄清效果,确定了最佳工艺条件,采用优化的澄清方法,苹果汁的透光率可达98％以上。论文对不同成熟期的苹果制汁的澄清工艺进行了调整,还探讨了澄清工艺对苹果汁主要成分的影响。     

不溶性壳聚糖对苹果汁脱色及澄清效果的研究

本论文对不溶性壳聚糖在苹果汁脱色及澄清中的作用进行了研究,初步确定了不溶性壳聚糖用量、温度、pH值对苹果汁色值和透光度的影响从而分别提出不溶性壳聚糖脱色的最佳工艺条件是:不溶性壳聚糖用量3.0g/100ml,温度35℃,pH值4.0不溶性壳聚糖澄清的最佳工艺条件是:不溶性壳聚糖用量2.5g/100ml,温度25℃,pH值4.0对不溶性壳聚糖装柱连续吸附法也进行了研究,结果表明此法可用于苹果汁的工业生产     

Differentiation of apple juice samples on the basis of heat treatment and variety using chemometric analysis of MIR and NIR data

The potential of mid-infrared (MIR) and near-infrared (NIR) spectroscopy for their ability to differentiate between apple juice samples on the basis of apple variety and applied heat-treatment was evaluated. The heat-treatment involved exposure of juice samples (15 ml) for 30 s in a 900 W microwave oven and the apple varieties used to produce the juice samples were Bramley, Elstar, Golden Delicious and Jonagold. The chemometric procedures applied to the MIR and NIR data were partial least squares regression (PLS1 for differentiation on the basis of heat-treatment, PLS2 for varietal differentiation) and linear discriminant analysis (LDA) applied to principal component (PC) scores. PLS1 and PLS2 gave the highest level of correct classification of the apple juice samples according to heat-treatment (77.2% for both MIR and NIR data) and variety (78.3–100% for MIR data; 82.4–100% for NIR data), respectively.     

Modeling the combined effects of pH, temperature and ascorbic acid concentration on the heat resistance of Alicyclobacillus acidoterrestis

In this study, thermal inactivation parameters (D- and z-values) of Alicyclobacillus acidoterrestris spores in McIlvaine buffers at different pH, apple juice and apple nectar produced with and without ascorbic acid addition were determined. The effects of pH, temperature and ascorbic acid concentration on D-values of A. acidoterrestris spores were also investigated using response surface methodology. A second order polynomial equation was used to describe the relationship between pH, temperature, ascorbic acid concentration and the D-values of A. acidoterrestris spores. Temperature was the most important factor on D-values, and its effect was three times higher than those of pH. Although the statistically significant, heat resistance of A. acidoterrestris spores was not so influenced from the ascorbic acid within the concentration studied. D-values in apple juice and apple nectars were higher than those in buffers as heating medium at similar pH. The D-values ranged from 11.1 (90 °C) to 0.7 min (100 °C) in apple juice, 14.1 (90 °C) to 1.0 min (100 °C) in apple nectar produced with ascorbic acid addition, and 14.4 (90 °C) to 1.2 min (100 °C) in apple nectar produced without ascorbic acid addition. However, no significant difference in z-values was observed among spores in the juices and buffers at different pH, and it was between 8.2 and 9.2 °C. The results indicated that the spores of A. acidoterrestris may survive in fruit juices and nectars after pasteurization treatment commonly applied in the food industry.     

Effect of ozone processing on the colour,rheological properties and phenolic content of apple juice

Apple juice samples were ozonated with processing variables of ozone concentration (1–4.8% w/w) and processing time (0–10 min). Effects of processing variables on colour values (L, a and b), rheological properties and phenolic content were studied. Significant reductions in these parameters were observed during ozonation. Second order polynomial regression modelling was used to investigate the main effects of ozone concentration and processing time on the changes in the selected quality parameters of ozonated apple juice. Predicted models were found to be significant (p < 0.05) with low standard error and high coefficients of determination (R²).     

Effect of previous enzymatic recirculation treatment through a tubular ceramic membrane on ultrafiltration of model solution and apple juice

The process of ultrafiltration of a model solution and 12% soluble solids apple juice containing pectins through tubular membranes of 100 and 300 kDa (1 and 3 channels) was studied. Furthermore, in order to obtain a higher permeate flow, the fluids were previously treated with pectinolytic enzymes recirculating through a tubular membrane at different concentrations and treatment times. The permeate flow was analyzed with respect to time and the influence of enzymatic treatment on different parameters: viscosity, density, absorbance at 420 nm, reducing sugars, °Brix, color and pH. Depectinization increased the permeate flow for the model solution and apple juice with 67.52% and 53.11% when the pectinolytic enzyme preparation re-circulated across the tubular membrane. Using the lowest concentration of enzyme treatment and the longest recirculation treatment, an increase in permeate flow was obtained leading to a more favourable clarification process and economic benefits.     

Influence of ultra-high pressure homogenisation on antioxidant capacity,polyphenol and vitamin content of clear apple juice

Ultra-high pressure homogenisation (UHPH) is a recently developed technology and is still under study to evaluate its effect on different aspects of its application to food products. The aim of this research work was to evaluate the effect of UHPH treatments on quality characteristics of apple juice such as antioxidant capacity, polyphenol composition, vitamin C and provitamin A contents, in comparison with raw (R) and pasteurised (PA) apple juice. Several UHPH treatments that include combinations of pressure (100, 200 and 300 MPa) and inlet temperatures (4 and 20 °C) were assayed. Apple juice was pasteurised at 90 °C for 4 min. Antioxidant capacity was analysed using the oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) assay while total phenolic content was determined by the Folin–Ciocalteau assay. According to the FRAP and DPPH assays, UHPH processing did not change apple juice antioxidant capacity. However, significant differences were detected between samples analysed by TEAC and ORAC assays. In spite of these differences, high correlation values were found between the four antioxidant capacity assays, and also with total polyphenol content. The analysis and quantification of individual phenols by HPLC/DAD analytical technique reflects that UHPH-treatment prevented degradation of these compounds. Vitamin C concentrations did not change in UHPH treated samples, retaining the same value as in raw juice. However, significant losses were observed for provitamin A content, but lower than in PA samples.     

Purification of polygalacturonase from Aspergillus awamori Nakazawa MTCC 6652 and its application in apple juice clarification

Polygalacturonase (PG) is necessary during fruit juice clarification process for the degradation of insoluble viscous pectinacious compounds. In the present study, PG from Aspergillus awamori Nakazawa MTCC 6652 produced by solid-state fermentation of mosambi (Citrus sinensis var mosambi) peel was decolorized and purified 34.8 fold with 69.8% recovery exploiting activated charcoal. The SDS-PAGE profiling revealed molecular weight of the purified PG as 30 kDa. The optimum pH and temperature of the purified enzyme were 4.5 and 50 °C, respectively. After decolorization and purification it was applied in the apple juice clarification process. The clarified juice exhibited 38% viscosity reduction with % T₆₆₀ of 93%, A₄₂₀ of 0.3 and pH 3.     

Clarification of apple juice by electroflotation

Apple Juice industry is in search of a simplified technology which enables a quick clarification and stabilisation of apple juice. This study aimed to evaluate the potential of electroflotation as an alternative for the clarification of apple juice. Clarification of apple juice by electroflotation was first done at various current densities (10, 20 and 40 mA/cm²) with and without addition of gelatin (200 mg/l). Afterwards, the electroflotation treatments were done at a current density of 20 mA/cm² with various concentrations of added gelatin (0, 50, 100 and 200 mg/l). It was shown that electroflotation treatments alone was efficient to reduce the tannin and protein contents of apple juice. However, the decrease in the protein content was in large part due to the use of pectinases prior to the electroflotation treatments. The use of gelatin in combination with the electroflotation aided in the clarification process. The highest gelatin concentration used in this study (200 mg/l) resulted in a better reduction of tannin and protein levels, while a current density of 20 mA/cm² was found to be optimal. Turbidity observed in the juices clarified with electroflotation treatments was in average lower than 10 NTU but higher than 2 NTU which is generally required to produce a stable clarified juice. Brix degree and pH of the apple juice was not affected by the electroflotation treatments while the color was improved.

Industrial relevance

The production of clarified and stable apple juice is a subject of interest for the beverages industries. The clarification step which remained long and discontinuous implied the addition of a large quantity of pectolytic enzyme and of clarifying agents (such as gelatin) to the freshly pressed juice to induce the precipitation of proteins and other suspended matter in 15–20 h. Fining treatments were followed by a separation step usually consisting of decantation and classical filtration on filter-press, or flotation by dispersed gas. The development of membrane separation processes to replace the traditional approach has enabled the automation of the whole production resulting in lower labor requirement and a considerably shorter process time than the traditional process.However, the performance of membrane separation processes is influenced by the declining permeate flux with time, which is due to membrane fouling. In some instances, permeate flux decline makes membrane separation processes unattractive for the clarification of apple juice. To our knowledge, we are the first research group to use electroflotation (EF) for clarification of apple juice. It was shown that EF treatments alone were efficient to reduce the tannin and protein contents of apple juice. In addition, the use of gelatin in combination with the EF aided in the clarification process. Turbidity observed in the juices clarified with EF treatments for 30 min was in average lower than 10 NTU. Brix degree and pH of the apple juice were not affected by the EF treatments while the color was improved.When compared to the values reported in the literature for flotation by dispersed gas, it seems that EF shows better efficiency than flotation in decreasing the juice turbidity (99% decrease for EF as compared to 90% decrease for flotation). In addition, for experiments carried out by conventional flotation larger amount of fining agent are used (70–150 mg of gelatin/l, 400–800 mg/l of silica sol and 200–500 mg/l of bentonite). For these reasons, the new process we propose is advantageous when compared to the traditional flotation approach and it should have a measurable impact on the advancements in the production of clarified apple juice. If used as a pre-treatment to ultrafiltration clarification, it is expected that it would reduce membrane fouling resulting in higher productivity.