Understanding and modeling high pressure assisted infusion of calcium in fruits and vegetables
Creators: name: Gosavi, Noopur Sanjay
Publisher: name: No Publisher Supplied
Year: 2021

description: High Pressure Processing (HPP) is a widely commercialized non-thermal batch processing technique in the food industry, that is aimed at improving the shelf-life and quality of foods through microbial and enzyme inactivation. Beyond this traditional application of HPP in foods, some researchers have explored its application to infuse nutrients (sugar, salt, etc.) and micronutrients (calcium, zinc, iron, anthocyanins, etc.) into food matrices with an aim to improve the textural and / or nutritional properties of those foods. The research reported in this dissertation explored whether HPP can infuse significant amounts of calcium in fruits and vegetables. If so, can we develop a mathematical model to quantify the effect of microstructure of the foods and pressure on the infused amount?Calcium lactate gluconate (CLG) was used as the infusing medium. All high pressure experiments were performed in the 10 L HPP vessel at Rutgers. Baby carrots were pre-treated with pectin methylesterase (PME) to enhance the infusion of calcium. Among pressure, time, and CLG solution concentration, CLG concentration was the most important parameter, followed by pressure, that affected the extent of calcium infusion in baby carrots, with increasing concentration leading to increased infusion. Processing the PME-pretreated baby carrots at 350 MPa for 15 min, using 9% CLG solution led to highest amount of calcium infusion (134 mg/85 g serving) in the baby carrots, which was &gt;10 % of the daily requirement of calcium for average adults. HPP infusion experiments were performed using baby carrots, celery, and mango – root, stem, and fruit, respectively. It was found that the transport tubes in baby carrots and celery were mainly responsible for the uptake of the infusate solution during HPP assisted infusion. In order to quantify the effect of microstructure of different food matrices, a protocol to stain and visualize the fruit and vegetable tissue under a light microscope was developed and the distributions of cell diameters (CDs) and cell wall thicknesses (CWT) were obtained. No statistical differences were observed in the CWT values across the different food matrices; however, the CD values were significantly different, within and across each system. It was observed that higher cell diameter in mango (76 ± 8 μm) led to highest infusion (111.02 ±14.03 mg/100 g fruit), followed by celery and baby carrots. Tagging the calcium with a fluorescent dye (Fluo-8) showed the infused calcium concentrated around the transport tubes in baby carrots and celery, while it was evenly distributed throughout the tissue in mangoes. To develop a mathematical model for infusion of calcium, experiments were performed using pre-permeabilized food matrices. Principal component analysis (PCA) and response surface analysis (RSA) showed that the microstructure of these foods was the primary factor in governing cell permeabilization and consequently the calcium infusion. A new effective microstructure term was defined such that it encompassed the effects of cell diameter and transport tubes which is a unique aspect of this study.