Perfecting Watermelon Juice Quality with Heat and Sound Techniques

Jenn Hoskins
16th June, 2024

Perfecting Watermelon Juice Quality with Heat and Sound Techniques

Image Source: Natural Science News, 2024

Key Findings

  • The study from the University of Venda explored thermosonication to preserve watermelon juice quality while minimizing nutrient loss
  • Thermosonication combines heat and ultrasound, retaining key nutrients like lycopene, β-carotene, ascorbic acid, and polyphenols
  • Optimal conditions (25°C, 2 minutes, 24 μm) resulted in high nutrient retention and minimal changes compared to fresh juice
Watermelon juice is a popular beverage known for its vibrant color, pleasant aroma, sweet taste, and low-calorie content. However, its neutral pH and high water activity make it highly perishable and susceptible to microbial contamination. Traditional thermal processing methods can degrade its sensitive nutrients, leading to a loss of its desirable qualities. A recent study from the University of Venda has explored thermosonication as an innovative technique to preserve the quality of watermelon juice while minimizing nutrient loss[1]. Thermosonication combines heat and ultrasound to process food products, aiming to retain their nutritional and sensory properties. The study employed response surface methodology, a statistical technique used to optimize processes, to determine the ideal conditions for thermosonication. The researchers tested various temperatures (18-52°C), processing times (2-13 minutes), and amplitude levels (24-73 μm) at a constant frequency of 25 kHz. The goal was to retain key quality parameters such as lycopene, β-carotene, ascorbic acid, and total polyphenolic content. The optimal conditions identified were 25°C, 2 minutes, and 24 μm, which resulted in lycopene content of 8.10 mg/100 g, β-carotene of 0.19 mg/100 g, ascorbic acid of 3.11 mg/100 g, and total polyphenolic content of 23.96 mg/GAE/g. These results were achieved with a desirability score of 0.81, indicating a high level of satisfaction with the outcomes. The model used in the study was statistically significant (p < 0.0001) and had a satisfactory determination coefficient (R2) of less than 0.8 for all phytochemicals. The findings showed that thermosonication caused minimal changes in the phytochemical properties of watermelon juice compared to fresh juice. Notably, the lycopene content increased significantly, and there was a substantial retention of β-carotene, ascorbic acid, and total polyphenolic content. This suggests that thermosonication could be a viable method for preserving watermelon juice with minimal quality loss and enhanced functional attributes. These findings align with previous research on the preservation of watermelon juice. For instance, a study comparing pasteurized and reconstituted watermelon juices found that pasteurization did not significantly impact most chemical components but did enhance typical watermelon aromas without forming off-flavor compounds[2]. However, reconstituted juice showed reduced levels of amino acids, phenolics, carotenoids, and most volatile compounds, indicating that vacuum concentration and reconstitution negatively impacted the juice's quality. Another study investigated the effects of Lactobacillus plantarum JHT78 fermentation on watermelon juice and found that fermentation significantly increased total polyphenols, flavonoids, and anthocyanins, enhancing antioxidant activities and altering both volatile and non-volatile compounds[3]. This highlights the potential of fermentation to improve the functionality of watermelon juice, although it involves a different preservation mechanism compared to thermosonication. Additionally, research on lycopene extraction from watermelon pulp demonstrated the importance of optimizing extraction conditions to maximize lycopene yield[4]. The study identified optimal conditions that resulted in a high lycopene content, which is a key nutrient in watermelon juice. This research underscores the significance of optimizing processing conditions to preserve and enhance the nutritional value of watermelon juice. In summary, the University of Venda's study on thermosonication offers a promising alternative to traditional thermal processing methods for preserving watermelon juice. By optimizing processing conditions, thermosonication can retain essential nutrients and improve the juice's functional attributes, making it a viable option for producing high-quality, nutrient-rich watermelon juice. This research contributes to the ongoing efforts to develop innovative technologies that minimize product degradation and meet consumer demand for natural, healthier, and safer beverages.

FruitsNutritionBiochem

References

Main Study

1) Optimization of thermosonication conditions for critical quality parameters of watermelon juice using response surface methodology.

Published 14th June, 2024

https://doi.org/10.1038/s41598-024-64066-9

Related Studies

2) Impact of sulfite use and acidification on chemical quality components in thermally processed watermelon juices.

https://doi.org/10.1016/j.foodres.2024.114088

3) Enhancement in the physicochemical properties, antioxidant activity, volatile compounds, and non-volatile compounds of watermelon juices through Lactobacillus plantarum JHT78 fermentation.

https://doi.org/10.1016/j.foodchem.2023.136146

4) Utilization of watermelon pulp for lycopene extraction by response surface methodology.

https://doi.org/10.1016/j.foodchem.2017.04.038


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