Effect of Food Microstructure on Calcium Infusion Under High Pressure

Abstract

The influence of food microstructure on high-pressure-assisted infusion of calcium was evaluated. Calcium was infused in baby carrots, celery pieces, and peeled mango cuboids, under varying pressures (100 to 500 MPa) using 6% calcium lactate gluconate. Microstructures of a baby carrot, celery, and mango were quantified before HPP in terms of their cell wall thickness (CWT) and cell diameter (CD). All samples had comparable CWT (4.5 to 5.5 μm), but differed in their CDs. CD and the amount of calcium infused were correlated. Mango had the largest cells (76 μm ± 8 μm) and the highest level of calcium infusion (111.02 ± 14.03 mg/100 g fruit). Cell breakage under high pressure, calculated as cell permeabilization index (ZP), significantly influenced the infusion, with higher cell breakage resulting in more infusion. However, the influence of ZP was observed within a given fruit/vegetable matrix but not across all the food matrices. This indicated that the microstructure, particularly CD and ZP together, played a role in calcium infusion under high pressure. The infused calcium was found to be concentrated around the transport tubes in the baby carrot and celery samples, while it was uniformly distributed in the mango samples, which indicated that the calcium uptake took place via the transport tubes and diffused into the surrounding cells. Following HPP-assisted calcium infusion, the cutting force (N) and the energy (J) required to cut the samples decreased, while the color of the processed samples became slightly darker (lower L* values) for all samples.