Ultrasonics Sonochemistry · 2015 · 174 citations · 58 references
AgricultureFood ScienceNutritional SciencesFood AnalysisFood ProcessingUltrasoundFruit NutritionFruit QualityFruit Quality EvaluationFruit Quality ImprovementJuice ProcessingJuice Composition AnalysisJuice SterilizationNutritional Quality RetentionPasteurizationProcessing Effects On NutrientsTotal Phenolic ContentUltrasound Processing EffectsVegetable Juices
Consumer awareness of the health benefits of nutrients has driven the need to evaluate how food processing methods affect quality attributes. This study investigates the impact of ultrasound and ultraviolet irradiation on the nutritional quality of orange, sweet lime, carrot, and spinach juices, comparing them to conventional 80 °C pasteurization for 10 min. Juices were treated with 20 kHz, 100 W ultrasound for 15 min or two 8 W 254 nm UV lamps, then analyzed for phenols, antioxidant activity, vitamin C, and carbohydrates, with a scale‑up of ultrasonic treatment for spinach juice assessed for 18‑day refrigerated shelf life. Ultrasound alone preserved the highest nutrient levels and extended shelf life, while the combined ultrasound‑UV approach achieved 5‑log microbial reduction but incurred slight nutrient losses compared to ultrasound alone, confirming ultrasound’s effectiveness over conventional pasteurization.
Increasing consumer awareness regarding the health benefits of different nutrients in food have led to the requirement of assessing the effect of food processing approaches on the quality attributes. The present work focuses on understanding the effects of novel approaches based on the use of ultrasound and ultraviolet irradiations on the nutritional quality of different fruit and vegetable juices (orange, sweet lime, carrot and spinach juices) and its comparison with the conventional thermal pasteurization operated at 80°C for 10 min. The ultrasound sterilization parameters were maintained at ultrasound frequency of 20 kHz and power of 100 W with treatment time as 15 min. For the case of ultraviolet irradiations, 2 UVC lamps (254 nm) of 8 W were placed in parallel on either sides of the reactor. The treated juices were analyzed for total phenol content, antioxidant activity, vitamin C, carbohydrates etc. It has been established that ultrasound processed juice retained most of the nutrient components to higher extent in comparison to all the other techniques used in the work. Combination of ultrasound and ultraviolet irradiations used to achieve an effective decontamination of juices (recommended 5 log reduction of microorganisms) also retained nutrients to a higher level in comparison to the thermal method; however some losses were observed as compared to the use of only ultrasound which could be attributed to inefficient heat exchange in the combined approach. A scale up attempt was also made for treatment of spinach juice using ultrasonic reactors and analysis for quality attributes confirmed that the juice satisfied the criteria of required nutrient contents for 18 days shelf life trial in refrigerated storage conditions. The present work has clearly established the usefulness of ultrasound based treatment in maintaining the nutritional quality of beverages while giving enhanced shelf life as compared to the conventional approaches.
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