Effects of ascorbic acid retention on juice color and pigment stability in blood orange (Citrus sinensis) juice during refrigerated storage

Blood orange juice samples with two different levels of ascorbic acid content were placed in HDPE plastic bottles, pasteurized, and stored at 4.5 °C. The influence of ascorbic acid retention on color stability of blood orange juice was investigated using CIE L*a*b*, hue, chroma, polymeric color, and browning index during the storage period. Changes in monomeric anthocyanin pigments, total carotenoid contents, cyanidin-3-glucoside, and ascorbic acid were also measured. Ascorbic acid degradation was highly correlated (r>0.93) to anthocyanin pigment degradation. Ascorbic acid content also showed linear correlation with red color intensity (CIE a*, and chroma) in the juice. Polymeric color and browning index increased with storage time and were more pronounced for juice fortified with ascorbic acid.     

Use of kinetic, Weibull and PLSR models to predict the retention of ascorbic acid, total phenols and antioxidant activity during storage of pasteurized pineapple juice

In this study, the usefulness of different mathematical models to predict the retention of ascorbic acid (AA), total phenols (TP) and DPPH radical scavenging activity (SA) of pasteurized pineapple juices during storage has been evaluated. The results indicate that first-order kinetic model provided the best prediction of the degradation of AA (MAE = 0.0059; MRE = 0.0117; MSE = 0.0001; R² = 0.9995) whereas Weibull model provided the less satisfactory prediction (MAE = 0.2387; MRE = 0.2911; MSE = 0.0769; R² = 0.9993). In addition, zero-order (MAE = 0.0016; MRE = 0.0017; MSE = 0.0000; R² = 0.9992) and first-order (MAE = 0.0027; MRE = 0.0029; MSE = 0.0000; R² = 0.9989) kinetic models are adequate models for application in the prediction of TP loss, and first-order kinetic (MAE = 0.0294; MRE = 0.0549; MSE = 0.0015; R² = 0.9845) and Weibull (MAE = 0.0533; MRE = 0.0881; MSE = 0.0044; R² = 0.9823) models are recommended to predict the change of SA. These results show that the behaviors of AA, TP and SA during storage of juices can be accurately described by different prediction models. Therefore, the selection of the most adequate model is of great importance to predict nutritional deterioration in food products during storage.     

Effect of high pressure processing on the stability of anthocyanin,ascorbic acid and color of Chinese bayberry juice during storage

The stability of anthocyanin (Cy3Gl) and ascorbic acid (AA) of pressure treated Chinese bayberry (Myrica rubra Sieb. et Zucc.) juice was investigated during storage at temperature of 4 °C and 25 °C. Samples of Chinese bayberry juice (350 mL each, packed with a polyethylene bag) were processed at 400, 500, 600 MPa in room temperature for 10 min. The retention ratio of Cy3Gl and AA content after pressure treatment was more than 98% and 96%, respectively. Both Cy3Gl and AA of pressure treated juice were more stable during storage as compared to those of the untreated control juice. The degradation of Cy3Gl and AA of samples during storage could be described using first order kinetic model. It was observed that there was a significant (p < 0.01) correlation between changes of Cy3Gl and AA content for all tested samples of Chinese bayberry juice during storage.     

Storage quality of pineapple juice non-thermally pasteurized and clarified by microfiltration

Microfiltration (MF) is classified as a non-thermal process for the fruit juice industry. It could provide a better preservation of the phytochemical property and flavor of the juice. This work aimed to study the stability of phytochemical properties including vitamin C, total phenolic content, antioxidant capacity (2-Diphenly-1-picrylhydrazyl: DPPH, free radical scavenging capacity and Oxygen Radical Absorbance Capacity: ORAC assays), microbial and chemical–physical (color, browning index, pH and total soluble solid) properties of MF-clarified pineapple juice during storage at various temperatures (i.e. 4, 27, and 37 °C). The juices were clarified by microfiltration using hollow fiber module. The results showed that most of the phytochemical properties and soluble components were retained in the juice after microfiltration. No microbial growth was detected after 6 months of storage. The storage time and temperature did not affect total soluble solids and pH (P > 0.05). The color (L^*) of clarified juice stored at 4 °C was lighter than the juices stored at higher temperature levels (P < 0.05). The phytochemical properties and total phenol content of the juice significantly decreased as storage time and temperature increased (P < 0.05). Vitamin C content was the attribute that affected storage time and temperature most as indicated by reaction rate constant and activated energy. Storage of non-thermally pasteurized and clarified pineapple juice at 4 °C was the most suitable since it allowed the best quality preservation.     

Non-enzymatic browning and ascorbic acid degradation of orange juice subjected to electroreduction and electro-oxidation treatments

Orange juice was submitted to electroreduction and electro-oxidation treatments prior to pasteurization and compared to a control juice for oxido-reduction potential (ORP), dissolved oxygen and ascorbic acid contents. Evolution of non-enzymatic browning reactions and ascorbic acid degradation was evaluated at 4, 21 and 37 °C storage temperatures. Electroreduction treatment of the juice at 6 V (cell length of 1.58 cm) created a substantial reducing reservoir as ORP decreased from + 161 to −406 mV and it decreased dissolved oxygen by more than 90% of its initial content while the ascorbic acid content was not altered. In contrast, the electro-oxidation treatment raised the final ORP of the juice by 15 to 20 mV, increased substantially the dissolved oxygen content and decreased significantly the ascorbic acid retention. Electro-oxidation treatment resulted in an increase of non-enzymatic browning reactions during storage. Both the control and electroreduced juice showed very similar trends in ascorbic acid degradation over the 3 months storage period whereas the anions, cations and amino acids profiles of the juice remain unchanged. Contrary to the control and electroreduced juices, the electro-oxidation process decreased severely the orange flavor intensity and character being characterized as musty with sour-bitter aftertaste.

Industrial relevance of electrolytic treatment to modulate the oxidation-reduction potential of comestible food systems

The limitation of shelf life imposed on comestible beverage systems (juice, beer, milk, wine, etc.) is an important and common issue for food manufactures and consumers. The shelf life is shortened by the time-dependent development of off-flavors, browning, change of colors, and deterioration of nutrients, caused by the oxidative reactions of chemical and nutrient components in the food systems. Consequently, the food is becoming unattractive to consumers. The electrochemical technique by means of an electrochemical cell has the potential in inhibiting or accelerating these deterioration reactions through reduction or oxidation of organic and inorganic compounds inherent to the products, as well as effectively controlling the oxygen content in the products. This technique can be used as an alternative to the deliberate addition of chemical compounds (sulfite and others reducing substances) to inhibit the deterioration reactions (electroreduction) as well as to accelerate the aging process of the comestible products via accelerated oxidation process (electro-oxidation).     

Maintaining the quality of sugarcane juice with blanching and ascorbic acid

The physicochemical changes in fresh sugarcane juice stored at 10 °C were studied by determining juice yield, color, reducing sugar, titratable acidity, viscosity, pH, polyphenol oxidase (PPO), sucrose neutral invertase (SNI) and total microbial count. Results showed that blanching of stems before squeezing effectively prevented degreening and/or browning, and reduced activities of PPO and SNI in fresh sugarcane juice. Added ascorbic acid delayed the increase of reducing sugar, titratable acidity, viscosity and total microbial count, and also prevented degreening and/or browning with reduced PPO and SNI activities in fresh sugarcane juice during storage. Addition of 0.1% ascorbic acid seemed to be more effective than blanching of sugarcane stems, and was able to maintain the quality of fresh sugarcane juice for up to 5 days at 10 °C. Deterioration of fresh sugarcane juice was demonstrated as a rapid increase of titratable acidity and viscosity with a obvious browning.     

Integrated effects of ascorbic acid,flavonoids and sugars on thermal degradation of anthocyanins in blood orange juice

This study aimed to elucidate how the major intrinsic factors, such as ascorbic acid (AA), flavonoids and sugars affected the thermal degradation of blood orange anthocyanins. The results in our study indicated that AA and sugars significantly accelerated anthocyanins degradation while flavonoids had a protective effect on degradation of anthocyanins. Flavonoids and AA could reduce the influence of temperature on anthocyanins degradation rate. However, the promoting effects of sugars on anthocyanins degradation correlated with the temperature. Moreover, the degradation of anthocyanins in the presence of sugars followed complex reaction kinetics when temperature was above 70 °C, and the promoting effects of sugars on anthocyanins degradation were glucose < sucrose < fructose. The results also indicated that flavonoids had a protective effect against either AA or sugars accelerated the degradation of anthocyanins, and this protective effect played a more important role in the degradation of anthocyanins comparing to the negative effect of AA or sugars. In addition, AA and sugars showed a synergistic effect on the degradation of anthocyanins at all our investigation temperatures except 90 °C.     

Effect of refrigerated storage on ascorbic acid content of orange juice treated by pulsed electric fields and thermal pasteurization

Application of pulsed electric fields (PEF) can lead to longer shelf life of fruit juices with minimal product quality loss and good retention of fresh-like flavour. The aim of this study was to evaluate the effect of PEF and conventional pasteurization (90 °C, 20 s) on ascorbic acid content of orange juice, and to assess modifications in ascorbic acid concentration of orange juice stored in refrigeration at 2 and 10 °C for 7 weeks. The ascorbic acid degradation rate was −0.0003, −0.0006, −0.0009 and −0.0010 μs⁻¹ for fields of 25, 30, 35 and 40 kV/cm, respectively. With selected PEF treatment (30 kV/cm and 100 μs) the shelf life based on 50% ascorbic acid losses was 277 days for the PEF-treated orange juice stored at 2 °C, while for the pasteurized juice was 90 days.     

Quantitative modelling approaches for ascorbic acid degradation and non-enzymatic browning of orange juice during ultrasound processing

The objective of this study was to develop a deterministic modelling approach for non-enzymatic browning (NEB) and ascorbic acid (AA) degradation in orange juice during ultrasound processing. Freshly squeezed orange juice was sonicated using a 1500 W ultrasonic processor at a constant frequency of 20 kHz and processing variables of amplitude level (24.4–61.0 μm), temperature (5–30 °C) and time (0–10 min). The rate constants of the NEB and AA were estimated by a primary model (zero and first order) while their relationship with respect to the processing factors was tested for a number of models, i.e., second order polynomial, different types of Ratkowsky-type model, and an Arrhenius-type model. The non-monotonic behaviour of NEB has been described more accurately by the use of a polynomial model. The rate constants of AA were described by a similar type of model having a monotonic behaviour. A synergistic effect of temperature for different amplitudes on the rate constant of both NEB and AA was observed, while an antagonistic effect of amplitude on the rate of NEB was evident. The models with the best fit were integrated to produce contour plots for the combined amplitude and temperature. The constructed contour plots illustrate that low temperatures and intermediate amplitudes, i.e., 42.7 μm, result in lower NEB and AA deterioration and consequently better quality orange juice. The overall developed modelling approaches exploit quality data in order to identify the optimal processing regions for eliminating quality deterioration of orange juice during ultrasound processing which is of high importance to the food industry.     

Tannase improves gallic acid bioaccessibility and maintains the quality of mango juice

The effect of tannase on gallic acid (GA) bioaccessibility and auto-oxidative browning of mango juice was investigated. After 2 h of simulated gastric digestion, the concentration of bioaccessible GA increased (P < 0.05) 94.3 ± 7.0% in juice treated with 0.5 U mL⁻¹ tannase while juice not treated with tannase had only a 6.3 ± 3.4% increase in GA. During 2–10 h of simulated intestinal digestion, tannase treated juice continued to have a higher concentration (P < 0.05) of bioaccessible GA in comparison to juice that was not treated with tannase. The use of 167 U 100 mL⁻¹ tannase while processing mango juice did not result in any differences (P < 0.05) in browning measured at 420 nm, yet there was significantly higher (P < 0.05) GA in mango juice post-storage. Processing mango juice with tannase can help improve the bioaccessibility of mango polyphenols without hindering the quality of juice during storage.     

Effects of pulsed electric field processing and storage on the quality and stability of single-strength orange juice

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22 degrees C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 micros and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22 degrees C for 112 days. PEF processing resulted in significant increases in the hydrocarbons D-limonene, alpha-pinene, myrecene, and valencene (P < or = 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22 degrees C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4 degrees C and in 2 days at 22 degrees C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P > or = 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4 degrees C for 112 days.     

The quality of orange juice processed by coupling crossflow microfiltration and osmotic evaporation

Crossflow microfiltration (CFM) and osmotic evaporation (OE) were implemented on a semi‐industrial pilot scale to obtain clarified orange juice concentrates at 450 and 620 g kg^?1 of total soluble solids. The characteristics of the juice were then assessed and compared with fresh juice and commercial concentrates. With CFM, most aroma compounds and vitamin C remained in the permeate while the more apolar compounds such as terpenic hydrocarbons and carotenoids were strongly retained by the membrane. With OE, significant losses of vitamin C and aroma compounds occurred at first, with losses progressively decreasing during treatment. Pre‐conditioning the membrane and cold regeneration of the brine reduced losses drastically, with the aroma composition tending towards that of the initial juice. The quality of pulp, a blend of the CFM retentate and OE concentrate, was high and much closer to that of the initial fresh juice than to the commercial thermal concentrate.     

脐橙果汁与果酒香气成分的GC-MS分析

采用溶剂萃取法分别提取脐橙果汁和经发酵后的果酒中的香气成分,经气相色谱质谱联用仪(GC-MS)分析,从果汁中鉴定出19种成分,占峰面积的83.5％,香气成分主要为苯乙醇、4-羟基-苯乙醇3-甲基-1-丁醇、D-柠檬烯、2,3丁二醇、巴伦西亚桔烯、亚油酸、油酸等:从果酒中鉴定出30种成分,占峰面积的91.13％,主要香气成分为苯乙醇、3-甲基-1-丁醇、d-柠檬烯、2,3丁二醇、乙酸乙酯、香叶醇、棕榈酸乙酯、3-乙氧基-1-丙醇、巴伦西亚桔烯、吲哚-3-乙醇、乙酸戊酯等.     

毛细管气相色谱法同时测定果汁中山梨酸、苯甲酸、脱氢乙酸

目的建立同时快速测定果汁中山梨酸、苯甲酸、脱氢乙酸的毛细管气相色谱法。方法果汁样品经液-液萃取后,样品中山梨酸、苯甲酸、脱氢乙酸经过毛细管柱分离,气相色谱FID检测器进行检测。结果本方法在10 min内可完成定性和定量检测,方法的线性范围为100～500 mg/L,线性相关系数都大于0.999,3种添加剂的测定结果的相对标准偏差(n=7)都小于3%,山梨酸、苯甲酸、脱氢乙酸在100、300、600 mg/L添加水平的回收率为89.9%～108.9%。结论该方法快速、灵敏、性价比高,适合测定果汁中山梨酸、苯甲酸、脱氢乙酸的测定。     

Physicochemical parameters,bioactive compounds and microbial quality of sonicated pear juice

This study was carried out to investigate the effect of sonication on physicochemical parameters and microorganisms of pear juice. Ultrasound processing of fresh pear juice was done at fixed amplitude [70% (500 W) and frequency (25 kHz) for 0, 15, 30, 45 and 60 min at 25 °C. Total soluble solids, pH, titratable acidity and Ca and Mn remained stable, while the cloud value, ascorbic acid, total phenols, total flavonoids, total antioxidant capacity, sugar contents and Na, K, Fe and Mg showed a significant increase. Decreases in microbial population and P and Cu were also observed. It may be inferred that ultrasound processing for 60 min exhibited optimum results in terms of physicochemical and microbial quality.     

Influence of high pressure homogenization and pulp reduction on residual pectinmethylesterase activity,cloud stability and acceptability of Lane Late orange juice: A study to obtain high quality orange juice with extended shelf life

Lane Late orange juice with extended shelf life (3 months at 3 °C) was obtained by high pressure homogenization (HPH) at 150 MPa at 68 °C for 15 s. Residual pectinmethylesterase (PME) inactivation level achieved was 75% but its cloudiness was maintained during storage and its acceptability undistinguishable from that of fresh juice during the assayed period. Juices with entire and reduced (50% and 25%) pulp contents were also homogenized at 150 MPa at different temperatures (63 °C and 58 °C for 15 s) to establish an appropriate shelf life of orange juices according to a desired level of cloudiness. Results showed how cloud stability of pulp reduced samples, even with a residual PME inactivation level above 90%, was not satisfactory (as in the case of entire juices homogenized out of 68 °C). The proposed methodology can easily be implanted by citrus industry to obtain high quality chilled orange juices with prolonged shelf life.