116: Impact of Cooling Die Temperature, Screw Speed, and Moisture Content on the Textural Properties of High-Moisture Meat Analogs

Introduction

Plant-based meat analogs mimic the texture of conventional meat by restructuring plant proteins. The organoleptic properties of high-moisture meat analogs (HMMA) are determined by the combination of product formulation, equipment parameters, and operating conditions. However, the exact interplay between these sets of parameters and their impact on the texture and quality of HMMA is not well understood.

In this study, we used response surface analysis to evaluate the effects of screw speed, moisture content, and cooling die temperature on the properties of HMMA.

Methods

Extrusion trials were conducted on a 27 mm corotating, intermeshing twin-screw extruder, used in conjunction with a flat, rectangular cooling die. Pea protein isolate was used as the protein source.

A central composite design (CCD) was developed to study the impact of three factors including screw speed, moisture content, and cooling die temperature at two levels each. Screw speed ranged from 600 to 1000 rpm, moisture content from 55% to 65%, and cooling die temperature from 100°F to 150°F. The extrudates were characterized for texture profile properties—hardness, springiness, chewiness, and cohesiveness—and anisotropy index. Response surface regression was performed on each of the extrudate characteristics, using a second order polynomial function. This design allowed for the evaluation of linear, quadratic, and interaction effects of the factors on the texture of HMMA.

Results

For all responses, moisture content was found to be the most significant factor impacting texture. The p-value for moisture content for all five responses was in the order of 0.001. The quadratic effects of moisture content were also significant for hardness (p = 0.0013) and chewiness (p = 0.0012). The quadratic effects of screw speed were marginally significant for hardness, chewiness and cohesiveness, in the order of ~0.053. Cooling die temperature within the range investigated, did not have a statistically significant impact on the texture and anisotropy index of HMMA.

Significance

By quantifying how screw speed, moisture content, and cooling die temperature interact to influence the texture of HMMA, this study provides valuable insights for improved process design. Learnings from this study can be applied to identify optimal operating conditions that yield HMMAs with desired properties.

Authors: Halak N. Mehta, Audrey Searing Hettel, George Nyombaire, Dharmendra K. Mishra