Orange Juice pH Research Articles

Extraction optimization and microencapsulation of Berberine from Berberis vulgaris incorporated in a functional orange drink: Physiochemical attributes and kinetic release studies

BACKGROUND: Berberine, extracted from Berberis vulgaris, is one of the well-known natural antioxidant sources. OBJECTIVE: Optimizing the berberine extraction conditions from the whole Barberry plant and microencapsulation of the optimized extract to be used as a bioactive ingredient in functional orange juice. METHODS: Seventeen extraction processes were designed to determine an optimized method for producing an ethanol/water extract with maximum yield, safety, and antioxidant properties. The optimal extract was microencapsulated by complex coacervation using tragacanth/gelatin and then spray-dried. The selected microcapsules based on morphology, particle size, and solubility were added to orange juice, and the physical and sensory properties of the functional drink, as well as the kinetic release models, were analyzed. RESULTS: An optimal extract with 82% antioxidant activity was prepared using a 75% ethanol/water ratio and an extraction time of 0.5 h at 22.3°C. Spherical-shaped microcapsules could create a desirable cloudy appearance with good stability in the pH of orange juice. The kinetics of the berberine release revealed an initial burst phase followed by a prolonged one, which would appeal to consumers’ sensory perceptions. CONCLUSIONS: The excellent compatibility between berberine and orange juice provides a potential capacity to fortify a high-consumption drink with a phytonutrient presented in a berry fruit.

Effects of kiwi's pectin methylesterase inhibitor, nanomilling and pasteurization on orange juice quality.

Endogenous pectin methylesterase (PME) is the enzyme responsible for phase separation and cloud loss in orange juice (OJ) manufacturing. The effect of kiwi's PME inhibitor (PMEI), nanomilling, and pasteurization on OJ quality was evaluated. The microbial quality, PME activity, OJ separation, pH, ascorbic acid content and the sensory characteristics of the juice were followed during 5 weeks storage (4°C). PMEI as freeze‐dried kiwi powder (0.3%, w/w) succeeded in inhibiting 89.3% of the OJ PME without affecting the microbial and the sensory quality. Nanomilling of OJ pulp, to prepare nano‐particles OJ (NPOJ), reduced the initial microbial load by 1.65 and 1.83 log for psychrotrophs and yeasts and molds, respectively; significantly (p < .05) inactivated 40.9% of the residual PME activity and the juice separation was significantly reduced by 48.3% (after 14 days of storage). Nanomilling exhibited no effect on OJ pH, but slight (p < .05) decrease in ascorbic acid content was noted. The combination of PMEI with NPOJ resulted in improved OJ stability with reduced separation to 36.4% of that of control. Such combination also allowed to use a lower pasteurization temperature at lower exposure time (60°C/5 min) needed to obtain new NPOJ with comparable high quality as fresh OJ and which has a shelf life of 3 weeks (4°C).

국내 시판 오렌지주스 및 자몽주스의 이화학적 특성과 항산화 활성

Thee physicochemical properties, functional ingredient content, and antioxidant activities of the commercial orange and grapefruit juice were investigated. Three types of orange (OJ1, OJ2, and OJ3) and grapefruit (GJ1, GJ2, and GJ3) juices were purchased from the market. Antioxidant activities of the commercial juices were evaluated using DPPH, ABTS, and reducing power assays. The pH of orange juice was higher than grapefruit juice and the acidity of grapefruit juice was higher than orange juice. The soluble solid and reducing sugar contents of the juices were in the range of 9.30-13.60 °Brix and 45.02-71.52 mg/mL, respectively. The total free sugar and organic acid contents of juices were 61.84-98.67 mg/mL and 1.14-1.60 mg/mL, respectively. The major free sugars were sucrose, fructose, and glucose, and six types of organic acids were detected in the commercial juices. The total polyphenol content was the highest in OJ2 (910.7 μg/mL), and the lowest in GJ3 (630.7 μg/mL). The total flavonoid content in grapefruit juices was higher than orange juices. OJ2 showed the highest antioxidant activity in DPPH and ABTS radicals scavenging assays and the reducing power assay. Our results indicate that the functional ingredient content and antioxidant activities were different even in the same type of juice.

THE EFFECT OF HEAT AND MICROWAVE TREATMENTS ON ORANGE JUICE QUALITY DURING STORAGE

The effect of heat and microwave (MW) treatments on quality related parameters as ascorbic acid (AA), browning index (BI), reducing sugar (RS), total soluble solid percentage (TSS %), and pH of orange juice (OJ) were investigated directly after the treatments and after storage at 4 and 20°C for 2 months. Microwave treatment induced little reduction in AA compared to heat treatment. Microwave treatment ensured the quality stability of orange juice stored for 2 months under refrigeration (4°C) but inferior orange juice quality was detected after 2 month storage at 20°C. Using MW exposure above 60 sec gave better studied parameters than heat treatments. However, microwave exposure for more than 60 sec. was sufficient to preserve the OJ quality. Accordingly, the use of microwave energy may be proposed as an alternative to traditional heat treatment in order to preserve the OJ quality.

Assessing the impact of immersing teeth in fresh orange juice and commercial orange juice on enamel hardness: an in vitro study

The pH of orange juice is below the critical pH of the enamel. Lately, consumption of orange juice has considerably increased because of its commercial availability. This study aims to investigate the impact of immersion time and juice types, both fresh and packaged, on enamel hardness. 60 premolars were immersed in fresh orange juice (n = 30) and commercial juice (n = 30) for 30 and 60 min and assessed the obtained data using repeated analysis of variance, Friedman test, Mann–Whitney U-test, and independent t-test. Enamel hardness decreased (P < 0.05) at every assessed time, and the commercial juice immersion significantly decreased the enamel hardness (P < 0.05). This study infers that enamel hardness is adversely affected by the pH, citric acid concentration, and immersion time of the orange juice.

Improvement of Orange Juice Preservation by Dynamic High-Pressure Processing

Effects of dynamic high-pressure (DHP) treatments with and without integration with heating on microbial stability, vitamin C concentration, color, sugar content, and pH of orange juice were studied and compared with those of the conventional thermal treatment. Freshly squeezed orange juice was heated at 90C for 1 min or DHP-treated at 205 MPa and 20, 50, 60, or 70C. The DHP treatment at 20C without heating and the treatment at 50C inactivated indigenous mesophilic aerobic microorganisms in orange juice by 4.2 and >7 log CFU/mL, respectively. The DHPtreated juice exhibited brighter color and higher vitamin C concentration and sugar content than the thermally treated juice, regardless of integration with heating. The DHP-treated juice demonstrated brighter color and higher sugar contents than untreated juice and thermally treated juice during storage at 4C for 63 days. The results have demonstrated the potential of applying DHP treatments to pasteurize orange juice with increasing brightness and sugar content of the juice.

Survival of Escherichia coli O157:H7 during Storage in Pressure-Treated Orange Juice

The effect of a high-pressure treatment on the survival of a pressure-resistant strain of Escherichia coli O157:H7 (NCTC 12079) in orange juice during storage at 3°C was investigated over the pH range of 3.4 to 5.0. The pH of shelf-stable orange juice was adjusted to 3.4, 3.6, 3.9, 4.5, and 5.0 and inoculated with 108 CFU ml−1 of E. coli O157:H7. The orange juice was then pressure treated at 400 MPa for 1 min at 10°C or was held at ambient pressure (as a control). Surviving E. coli O157: H7 cells were enumerated at 1-day intervals during a storage period of 25 days at 3°C. Survival of E. coli O157:H7 during storage was dependent on the pH of the orange juice. The application of high pressure prior to storage significantly increased the susceptibility of E. coli O157:H7 to high acidity. For example, after pressure treatment, the time required for a 5-log decrease in cell numbers was reduced from 13 to 3 days at pH 3.4, from 16 to 6 days at pH 3.6, and from >25 to 8 days at pH 3.9. It is evident that the use of high-pressure processing of orange juice in order to increase the juice's shelf-life and to inactivate pathogens has the added advantage that it sensitizes E. coli O157:H7 to the high acid conditions found in orange juice, which results in the survival of significantly fewer E. coli O157:H7 during subsequent refrigerated storage.

Viability of Lactobacillus plantarum in Orange Juice under Low pH and Temperature Conditions

ABSTRACTA strain of Lactobacillus plantarum, isolated from fermenting orange juice (OJ), was inoculated into unpasteurized or reconstituted OJ and held under low pH/low temperature conditions. Viability decreased more rapidly at subfreezing temperatures near – 5°C than at lower or higher temperatures. Viability decreased 0.37 log CFU/mL/hr at ‐ 6.6°C and 0.05 log CFU/mL/hr at ‐ 18°C. Rates of population decrease in frozen samples at ‐ 5°C were about three times greater than in unfrozen samples at the same temperature. An inverse linear relationship existed between rate of population decrease (log CFU/mL/day) at ‐ 7°C and OJ pH, with the rate of decrease at pH 4.1, about 1 log cycle lower than at pH 3.5 (0.024 and 0.60, respectively).

Calcium bioavailability and iron-calcium interaction in orange juice.

We have determined the effects of orange juice on calcium bioavailability from CCM (a combination of CaCO3, citric acid, malic acid, 5:1:1, mol/mol/mol) and iron-calcium interaction by using whole body isotope retention techniques in rats. The mean calcium retention values from CCM were 42.8% from orange juice and 33.0% from water, a control. Orange juice significantly (p less than 0.05) improved calcium bioavailability. This enhancement of calcium absorption is independent of orange juice's pH and citric acid. Iron absorption from orange juice with CCM (36.7%) was also significantly higher than that from control (water) plus CCM (12.3%). Ascorbic acid at levels naturally present in orange juice failed to improve iron retention (12.3% vs 12.5%) from water plus CCM. In contrast, citric acid (at orange juice level) significantly (p less than 0.05) promoted iron absorption in the presence of CCM (8.0% vs 23.7%). The benefit of citric acid on iron-calcium interaction is enhanced by ascorbic acid. In the presence of both citric acid and ascorbic acid, at orange juice levels, iron absorption from water plus CCM (37.6%) was comparable to that from water without CCM (34.5%). These results show orange juice can deliver bioavailable calcium from CCM with minimal inhibition of iron absorption. Citric acid and ascorbic acid are likely the major orange juice components that contribute to the alleviation of iron absorption inhibition by CCM.