123: Microwave Vacuum Drying for Crispy Beet Snacks: Process Development, Drying Kinetics, and Product Qualities

Introduction

Crispy snacks are becoming increasingly popular in modern diets. Conventional products are prepared from ultra-processing methods (such as deep frying) with added sugar, salt, and lipids, and may contribute to health issues. Developing new vegetable snack products that are crispy, flavorful, and nutritionally balanced using advanced processing technologies aligns with consumer demands while also improving their health. MVD reduces water's boiling point and volumetrically heats foods at relatively low temperatures, which allows efficient drying with mitigated nutrient and sensory losses under moderate conditions. This study aimed to develop an MVD process for producing crispy beet chips and analyze drying kinetics and product qualities.

Methods

Freshly cut beet slices were subjected to different pretreatment methods (steam-blanching, hot air pre-drying, freezing), then dried in a pilot-scale MVD unit at 3.0, 4.5, and 6.0 W/g initial power densities. Experiments were performed with triplicate. The product moisture content, drying rates, drying time, color metrics and texture properties were measured in time series throughout the drying process with statistical analysis and compared with freeze drying (FD).

Results

Drying curves showed an exponential-decay pattern, suggesting that the drying process was diffusion-controlled. The best color and texture properties were achieved under steam-blanching for 4 minutes at 212℉ followed by hot air drying for 10 minutes at 190℉, and MVD at 4.5 W/g. The drying time was 22.5 min to achieve <0.4 water activity (compared to overnight for FD), with blistering (puffed structures) on the surface. MVD beet chips had harder texture, smaller size, and darker colors compared to FD.

Significance

MVD could produce shelf-stable beet snacks with desirable crispiness and color with much higher efficiency than FD. The new product offers a healthier and creative way of eating vegetables and follows modern diet trends for convenience and sensory pleasure, which could result in higher consumer acceptance. Study of the drying kinetics laid the foundation for further optimization of the MVD process for better quality preservation.

Authors: Diane Makovic, Sofia Bielinski Leitao, Kyra Husen, Chang Chen, Olga I. Padilla-Zakour