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Novel processing techniques and spinach juice: Quality and safety improvements.
Muhammad Faisal Manzoor1,2, Zahoor Ahmed1,2, Nazir Ahmad3
1School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China.
Journal of Food Science
|March 30, 2020
Summary
Combining ultrasound (US) and pulsed electric field (PEF) treatments significantly enhances spinach juice quality and microbial safety. This nonthermal approach boosts minerals and amino acids while reducing microbial load and particle size for industrial applications.
Area of Science:
- Food Science and Technology
- Nonthermal Processing
- Food Microbiology
Background:
- Nonthermal technologies such as ultrasound (US) and pulsed electric field (PEF) are increasingly utilized for improving the quality and stability of fruit and vegetable juices.
- Optimizing these technologies is crucial for enhancing nutritional content and ensuring microbial safety in processed foods like spinach juice.
Purpose of the Study:
- To investigate the combined effects of ultrasound (US) and pulsed electric field (PEF) on the quality improvement and microbial safety of spinach juice.
- To evaluate the impact of US-PEF treatment on nutritional components, microbial load, particle size, and rheological properties of spinach juice.
Main Methods:
- Spinach juice was subjected to ultrasound treatment (40 kHz, 200 W, 21 min) and pulsed electric field treatment (9 kV/cm, 335 µs).
- Combined US-PEF treatment was applied to assess synergistic effects.
- Analysis included mineral content, total free amino acids, microbial counts (total plate count, E. coli/Coliform, yeast and mold), particle size, and rheological properties (viscosity, flow behavior).
Main Results:
- The combined US-PEF treatment resulted in the highest content of minerals and total free amino acids compared to individual treatments.
- Significant reductions in total plate count (1.97 log CFU/mL), E. coli/Coliform (0.75 log CFU/mL), and yeast and mold (2.22 log CFU/mL) were observed.
- US-PEF treatment decreased particle size and altered rheology, indicating non-Newtonian behavior with reduced consistency index and apparent viscosity, and increased flow behavior index.
Conclusions:
- The combined US-PEF nonthermal processing is effective in enhancing the nutritional quality (minerals, amino acids) and microbial safety of spinach juice.
- This technology significantly reduces microbial populations and particle size, offering a viable alternative for industrial-scale spinach juice processing.
- While rheological properties are altered, the overall quality improvement supports the suitability of US-PEF for commercial applications.
