Changes of colour and carotenoids contents during high intensity pulsed electric field treatment in orange juices

Equivalent processing for pasteurization of a pineapple juice-coconut milk blend by selected nonthermal technologies

Identifying equivalent processing conditions is critical for the relevant comparison of food quality attributes. This study investigates equivalent processes for at least 5-log reduction of Escherichia coli and Listeria innocua in pineapple juice-coconut milk (PC) blends by high-pressure processing (HPP), pulsed electric fields (PEF), and ultrasound (US) either alone or combined with other preservation factors (pH, nisin, and/or heat). The two blends (pH 4 and 5) and coconut milk (pH 7) as a reference were subjected to HPP at 300-600 MPa, 20°C for 0.5-30 min; PEF at an electric field strength of 10-21 kV/cm, 40°C for 24 µs; and US at 120 µm amplitude, 25 or 45°C for 6 or 10 min. At least a 5-log reduction of E. coli was achieved at pH 4 by HPP at 400 MPa, 20°C for 1 min; PEF at 21 kV/cm, 235 Hz, 40°C for 24 µs; and US at 120 µm, 45°C for 6 min. As L. innocua showed greater resistance, a synergistic lethal effect was provided at pH 4 by HPP with 75 ppm nisin at 600 MPa, 20°C for 5 min; PEF with 50 ppm nisin at 18 kV/cm, 588 Hz, 40°C for 24 µs; and US at 45°C, 120 µm for 10 min. The total soluble solids (11.2-12.4°Bx), acidity (0.47%-0.51% citric acid), pH (3.91-4.16), and viscosity (3.55 × 10^-3 -4.0 × 10^-3  Pa s) were not significantly affected under the identified equivalent conditions. HPP was superior to PEF and US, achieving higher ascorbic acid retention and lower color difference in PC blend compared to the untreated sample.

Effect of high intensity ultrasound on main bioactive compounds, antioxidant capacity and color in orange juice

Ultrasound is a useful alternative to thermal processing that can be applied to many food products and juices to aid with enzymes and microorganism inactivation and to improve the efficiency of unit operations generally applied in the food industry. The aim of this study was to evaluate the effect of a high-intensity sonication treatment (frequency 20 kHz; intensity 39.4 W/cm²) applied for treatment times from 0 to 105 min on the content of polyphenols, vitamin C, organic acids, and carotenoids, and on the hydrophilic and lipophilic antioxidant capacity and color of orange juice. Treatments were performed in triplicate and data was statistically analyzed. Sonication time did not have a significant effect (P > 0.05) on total polyphenols, total vitamin C, organic acid, and carotenoid contents, lipophilic antioxidant capacity, or juice color. The hydrophilic antioxidant activity and the lutein content increased significantly (P < 0.05) with increased sonication time. These results may be useful as a baseline for the development of sonication treatments that could be used in combination with other traditional and emerging processing approaches to protect the most important bioactive compounds and quality properties of orange juice.

Irradiance and Temperature Influence the Bactericidal Effect of 460-Nanometer Light-Emitting Diodes on Salmonella in Orange Juice

Blue light-emitting diodes (LEDs) have been known to produce an antibacterial effect on various pathogenic bacteria. To extend this application to foods, blue 460-nm LEDs were evaluated for their antibacterial effect on Salmonella in orange juice. A cocktail of Salmonella enterica serovars Gaminara, Montevideo, Newport, Typhimurium, and Saintpaul was inoculated into pasteurized orange juice and illuminated with 460-nm LEDs at irradiances of 92, 147.7, and 254.7 mW/cm(2) and temperatures of 4, 12, and 20°C. Subsequently, linear, Weibull, and Gompertz models were fitted to the resultant survival curves. The color of the orange juice during illumination was also monitored. It was observed that irradiance and temperature both influenced the inactivation of Salmonella, which ranged from 2 to 5 log CFU/ml. The inactivation kinetics was best described by the Weibull model. An irradiance of 92 mW/cm(2) and temperatures of 12 and 20°C were the most bactericidal combinations, with D-values of 1,580 and 2,013 J/cm(2), respectively. Significant color changes were also observed after illumination; these changes could be minimized by choosing appropriate irradiance and temperature. These results demonstrate the potential of 460-nm LEDs for the preservation of fruit juices in the retail markets and their utility in minimizing the risk of salmonellosis.

Bioactive compounds in pindo palm (Butia capitata) juice and in pomace resulting of the extraction process

BACKGROUND

Pindo palm (Butia capitata, Becc. 1916) is a tropical fruit native to South America and is relatively rich in bioactive compounds. It is often consumed as juice. The aim of this study was, first, to identify the degradation of these compounds by pasteurization and by cold storage (4 °C) of pindo palm juice. Physicochemical properties and concentrations of phenolic compounds, carotenoids and vitamin C have been evaluated on fresh and pasteurized juices. Moreover, another objective was to characterize the nutritional composition and the bioactive compounds of pindo palm pomace, the by-product of juice processing.

RESULTS

The results demonstrated a degradation of carotenoids with pasteurization and a degradation of vitamin C with both pasteurization and cold storage of juices. Furthermore, the evaluation of pindo palm pomace showed that it is relatively rich in total phenols (20.06 g gallic acid equivalents kg(-1) dry matter) and in β-carotene (0.22 g kg(-1) dry matter).

CONCLUSION

Thus, from the nutrition viewpoint, it does not seem interesting to pasteurize juice. On the other hand, extraction of carotenoids and phenolic compounds from the pomace appears to be a relevant process.

Chemistry and biotechnology of carotenoids

Carotenoids are one of the most widespread groups of pigments in nature and more than 600 of these have been identified. Beside provitamin A activity, carotenoids are important as antioxidants and protective agents against various diseases. They are isoprenoids with a long polyene chain containing 3 to 15 conjugated double bonds, which determines their absorption spectrum. Cyclization at one or both ends occurs in hydrocarbon carotene, while xanthophylls are formed by the introduction of oxygen. In addition, modifications involving chain elongation, isomerization, or degradation are also found. The composition of carotenoids in food may vary depending upon production practices, post-harvest handling, processing, and storage. In higher plants they are synthesized in the plastid. Both mevalonate dependent and independent pathway for the formation of isopentenyl diphosphate are known. Isopentenyl diphosphate undergoes a series of addition and condensation reactions to form phytoene, which gets converted to lycopene. Cyclization of lycopene either leads to the formation of β-carotene and its derivative xanthophylls, β-cryptoxanthin, zeaxanthin, antheraxanthin, and violaxanthin or α-carotene and lutein. Even though most of the carotenoid biosynthetic genes have been cloned and identified, some aspects of carotenoid formation and manipulation in higher plants especially remain poorly understood. In order to enhance the carotenoid content of crop plants to a level that will be required for the prevention of diseases, there is a need for research in both the basic and the applied aspects.

Influence of pasteurization, spray- and freeze-drying, and storage on the carotenoid content in egg yolk

A liquid chromatography-atmospheric pressure chemical ionization mass spectrometry [LC-(APCI)MS] method was developed to identify and quantify the carotenoids present in fresh, pasteurized, and freeze- and spray-dried egg yolk in two independent batches. The egg yolk powders in each batch were stored in the dark for 6 months at -18 or 20 degrees C. Carotenoids were isolated by solvent extraction without saponification and analyzed by HPLC using a C(30) column coupled to a photodiode array and mass detector. The most abundant carotenoids were all-E-canthaxanthin, all-E-lutein, all-E-zeaxanthin, 9-Z-canthaxanthin, and beta-apo-8'-carotenoic acid ethyl ester. Pasteurization of the egg yolk caused no critical changes in the carotenoid content. On the contrary, drying to a dry matter of 98-99% led to higher carotenoid contents, induced by a denaturation of binding proteins, and a destabilization of the cell matrix. After the 6 months of storage, the contents of all main carotenoids in the egg yolk powder were significantly lower. The synthetic carotenoids canthaxanthin and beta-apo-8'-carotenoic acid ethyl ester showed a higher retention rate, and the greatest losses occurred within the first 8 weeks. Statistical tests (ANOVA, P < 0.05) also proved that after 26 weeks, the egg yolk powders stored at -18 degrees C showed only a slightly higher retention of carotenoids when compared to the powders stored at 20 degrees C.

Impact of High-Intensity Pulsed Electric Fields on Bioactive Compounds in Mediterranean Plant-based Foods

Novel nonthermal processing technologies such as high-intensity pulsed electric field (HIPEF) treatments may be applied to pasteurize plant-based liquid foods as an alternative to conventional heat treatments. In recent years, there has been an increasing interest in HIPEF as a way of preserving and extending the shelf-life of liquid products without the quality damage caused by heat treatments. However, less attention has been paid to the effects of HIPEF on minor constituents of these products, namely bioactive compounds. This review is a state-of–the-art update on the effects of HIPEF treatments on health-related compounds in plants of the Mediterranean diet such as fruit juices, and Spanish gazpacho. The relevance of HIPEF-processing parameters on retaining plant-based bioactive compounds will be discussed.

Lycopene, vitamin C, and antioxidant capacity of tomato juice as affected by high-intensity pulsed electric fields critical parameters

The effects of high-intensity pulsed electric field (HIPEF) treatment variables (frequency, pulse width, and pulse polarity) on the lycopene, vitamin C, and antioxidant capacities of tomato juice were evaluated using a response surface methodology. An optimization of the HIPEF treatment conditions was carried out to obtain tomato juice with the highest content of bioactive compounds possible. Samples were subjected to an electric field intensity set at 35 kV/cm for 1000 micros using squared wave pulses, frequencies from 50 to 250 Hz, and a pulse width from 1 to 7 micros, in monopolar or bipolar mode. Data significantly fit (P < 0.001) the proposed second-order response functions. Pulse frequency, width, and polarity significantly affected the lycopene, vitamin C, and antioxidant capacities of HIPEF-treated tomato juice. Maximal relative lycopene content (131.8%), vitamin C content (90.2%), and antioxidant capacity retention (89.4%) were attained with HIPEF treatments of a 1 micros pulse duration applied at 250 Hz in bipolar mode. Therefore, the application of HIPEF may be appropriate to achieve nutritious tomato juice.

Refrigerated fruit juices: quality and safety issues

Fruit juices are an important source of bioactive compounds, but techniques used for their processing and subsequent storage may cause alterations in their contents so they do not provide the benefits expected by the consumer. In recent years consumers have increasingly sought so-called "fresh" products (like fresh products), stored in refrigeration. This has led the food industry to develop alternative processing technologies to produce foods with a minimum of nutritional, physicochemical, or organoleptic changes induced by the technologies themselves. Attention has also focused on evaluating the microbiological or toxicological risks that may be involved in applying these processes, and their effect on food safety, in order to obtain safe products that do not present health risks. This concept of minimal processing is currently becoming a reality with conventional technologies (mild pasteurization) and nonthermal technologies, some recently introduced (pasteurization by high hydrostatic pressure) and some perhaps with a more important role in the future (pulsed electric fields). Nevertheless, processing is not the only factor that affects the quality of these products. It is also necessary to consider the conditions for refrigerated storage and to control time and temperature.