Basic spherification as a gelation application in the kitchen: Diffusion coefficient estimation and appearance quality of beverage pearls

Food ingredients are manipulated to produce spherical shapes with distinctive qualities through a process known as spherification. It is one of the methods used in molecular gastronomy to produce small balls mimicking caviar or other comparable shapes. In this study, beverage pearls of berry smoothie, orange juice, ginger ale, ice tea, cola, and ice coffee latte were prepared with basic spherification technique. Liquid mixtures were prepared with 100 ml of beverage, 1 g sodium alginate, and 0.25 g tri-sodium citrate; and 1 mol/L of calcium chloride solution was used for the bath. Spherification was conducted for 3, 6, 9, 12, and 15 min, and diameter and weight were measured. Inventory rate equation for calcium diffusion was written with quasi-steady state approximation to estimate diffusion coefficient of calcium ions. A linear equation was obtained with spherification time (t) and radius×radius (R2) variables. Diffusion coefficient was calculated between 2.2459 × 10−8 and 4.2431 × 10−8 m2/s. Appearance is one of the key factors considered in the quality analysis of spherified products. For 15 min spherification time, the highest total color change (ΔE) was seen in ice tea pearls and the lowest total color change value was observed in orange juice spheres. In addition, beverage pearls spherified for 15 min were observed with microscope to check the surface structures. This study will provide food professionals and chefs clarification of the science underlying the conversion of liquid ingredients into tasty pearls and help them to adjust spherification time and product color.