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Tiger nut milk is a low-acid health beverage that is marketed with the claims of being high in protein, monounsaturated fatty acid (oleic acid), fiber, starch, and minerals, in addition to...

Fresh juices are highly popular beverages in the global food market. They are perceived as wholesome, nutritious, all-day beverages. For a fast growing category of premium juice products such as cold-pressed juices, minimal-processing nonthermal techniques such as ultraviolet (UV) light and high-pressure processing (HPP) are expected to be used to extend shelf-life while retaining physicochemical, nutritional, and sensory characteristics with reduced microbial loads. Also, UV light and HPP are approved by regulatory agencies and recognized as one of the simplest and very environmentally friendly ways to destroy pathogenic organisms. One of the limitations to their more extensive commercial application lies in the lack of comparative effects on nutritional and quality-related compounds in juice products. This review provides a comparative analysis using 92 studies (UV light: 42, HPP: 50) mostly published between 2004 and 2015 to evaluate the effects of reported UV light and HPP processing conditions on the residual content or activity of bioactive compounds such as vitamins, polyphenols, antioxidants, and oxidative enzymes in 45 different fresh fruit and vegetable juices (low-acid, acid, and high-acid categories). Also, the effects of UV light and HPP on color and sensory characteristics of juices are summarized and discussed.

The Positron Emission Particle Tracking (PEPT) flow visualisation technique has been applied to determine the hydrodynamic performance of a full-scale transparent model of a SurePure Turbulator™ used for the microbial treatment of turbid dairy fluids using UV-C radiation. The effect of flow rate upon the refreshment of fluid at the surface of the UV source has been investigated using two model fluids each possessing the same viscosities as milk and cream respectively. The amount of surface refreshment is modelled as a time density function close the surface of UV-C source and incorporated into an existing first order microbial inactivation model and a Weibull distribution model. Fitting to experimental data obtained for the inactivation of selected milk pathogens using the Turbulator™ have demonstrated the superiority of the Weibull model. These models enable a more precise estimation of UV-C energy requirement for the inactivation of the milk borne pathogenic organisms to be made since the amount of surface refreshment affords a significant performance enhancement.

As a result of growing interest to nonthermal processing of milk, the purpose of this study was to characterize the chemical changes in raw milk composition after exposure to a new nonthermal turbulent flow UV process, conventional thermal pasteurization process (high-temperature, short-time; HTST), and their combinations, and compare those changes with commercially UHT-treated milk. Raw milk was exposed to UV light in turbulent flow at a flow rate of 4,000L/h and applied doses of 1,045 and 2,090 J/L, HTST pasteurization, and HTST in combination with UV (before or after the UV). Unprocessed raw milk, HTST-treated milk, and UHT-treated milk were the control to the milk processed with the continuous turbulent flow UV treatment. The chemical characterization included component analysis and fatty acid composition (with emphasis on conjugated linoleic acid) and analysis for vitamin D and A and volatile components. Lipid oxidation, which is an indicator to oxidative rancidity, was evaluated by free fatty acid analysis, and the volatile components (extracted organic fraction) by gas chromatography-mass spectrometry to obtain mass spectral profile. These analyses were done over a 14-d period (initially after treatment and at 7 and 14 d) because of the extended shelf-life requirement for milk. The effect of UV light on proteins (i.e., casein or lactalbumin) was evaluated qualitatively by sodium dodecyl sulfate-PAGE. The milk or liquid soluble fraction was analyzed by sodium dodecyl sulfate-PAGE for changes in the protein profile. From this study, it appears that continuous turbulent flow UV processing, whether used as a single process or in combination with HTST did not cause any statistically significant chemical changes when compared with raw milk with regard to the proximate analysis (total fat, protein, moisture, or ash), the fatty acid profile, lipid oxidation with respect to volatile analysis, or protein profile. A 56% loss of vitamin D and a 95% loss of vitamin A content was noted after 7 d from the continuous turbulent flow UV processing, but this loss was equally comparable to that found with traditional thermal processing, such as HTST and UHT. Chemical characterization of milk showed that turbulent flow UV light technology can be considered as alternative nonthermal treatment of pasteurized milk and raw milk to extend shelf life.

A novel industrial-scale ultraviolet-C (UV-C) light processor from AseptoRay (MGT, Israel) was used to treat a raw cold-pressed green juice blend (GJB) consisting of kale, romaine, celery, apple, and lemon. The effect of UV-C light energies of 0.88 kJ L−1 and 2.93 kJ L−1 on microbial, enzymatic, nutritional, quality, and sensory parameters of the GJB was studied. Using 2.93 kJ L−1, 3.7 log reduction in aciduric bacteria and 3.9 logs in aerobic colony count were achieved, while lactic acid bacteria, coliforms, yeasts, and moulds were reduced by >3, >2, 2.1, and 2.1 logs, respectively. A minor increase in polyphenoloxidase (PPO) enzyme activity was seen with 0.88 kJ L−1 and a slight change in colour (not visually observed) was detected using 2.93 kJ L−1. No other significant change in nutritional and quality parameters or enzyme activities was detected. Further, the stability of the GJB was explored. Kale and romaine contributed the most significant source of spoilage enzyme activity, cloud loss, and browning in the GJB. These stability parameters were shown to be affected by pressing temperature and pH. The commercial UV-C treatment process explored in this study is a viable alternative to high pressure processing (HPP) for improved microbial safety of fresh green juice blends.

The objective of this study was to validate the performance of a coiled ultraviolet (UV) module with 24 lamps for fresh juice pasteurization. Escherichia coli K12 at an inoculation level of 106 cfu mL–1 was chosen as a target microorganism for biodosimetry. All tested fruit juices highly absorbed UV light, with absorption coefficients ranging from 11 cm–1 to 78 cm–1 for lillikoi and pineapple juice, respectively. Of the juices examined, pineapple juice appeared to be the worst case scenario in terms of UV absorptivity and high viscosity. A caramel model solution was developed to mimic juice absorption properties and was used for inoculation studies. The 5-log10 reduction standard under turbulent flow required by the FDA was achievable in Newtonian liquids with absorption coefficient less than 15 cm–1 after one pass. Turbulent flow was not developed in more viscous orange and pineapple juices at the flow rates tested. A biodosimetry technique that utilizes E. coli as a tracer showed no distribution of UV dose in liquids with absorption coefficient lower than 26 cm–1. The proposed technique may assist in validating the performance of UV reactors and improve efficiency of UV pasteurization. Key words: coiled ultraviolet module, fruit juices, caramel model, E. coli K12, biodosimetry.

This study evaluated three UVC wavelengths (222, 254, and 282 nm) to degrade patulin introduced into apple juice or apple cider. The average UV fluences of 19.6, 84.3, 55.0, and 36.6 mJ·cm(-2) achieved through exposure to UV lamps at 222-, 254-, and 282-nm wavelengths and the combination of these wavelengths, respectively, resulted in 90% reduction of patulin in apple juice. Therefore, the order of efficiency of the three wavelength lamps was as follows: far UVC (222 nm) > far UVC plus (282 nm) > UVC (254 nm). In terms of color, treatment of apple juice with 222 nm resulted in an increase in the L* (lightness) value but decreases in a* (redness) and b* (yellowness) values, although the changes were insignificantly different from the values for nontreated controls based on a sensory evaluation. The ascorbic acid loss in juice treated at 222 nm to support 90% reduction of patulin was 36.5%, compared with ascorbic acid losses of 45.3 and 36.1% in samples treated at 254 and 282 nm, respectively. The current work demonstrated that the 222-nm wavelength possesses the highest efficiency for patulin reduction in apple juice when compared with the reductions by 254 and 282 nm, with no benefit gained from using a combination of wavelengths.