Rheological Properties of Purple Avocado (Persea Americana Mill.) Fruits at Different Ripening Stages

Abstract

Proper postharvest handling and management of perishable horticultural commodities require the proper understanding and the need for basic information on the mechanical properties of these commodities specifically for avocados to preserve quality and reduce losses and waste. Physical characterization and compression tests were conducted on avocados to develop an understanding of the rheological properties of avocados at different ripening stages, sizes, and compression loads. An appropriate equation in predicting volume from its weight and its shape signature that specifically represents the shape of the purple fruited avocado variety in a one-dimensional function were established. The shape of avocado fruits tends toward being spherical and expected to roll not slide as indicated by the mean values of sphericity and aspect ratio. The compressive strength of avocado varied with ripeness were small size can withstand up to 5 kg of load by weight after harvest without significant internal damage and 6 kg of load for medium size.

Avocado fruits had a time-dependent stress relaxation behavior like other viscoelastic material. The threeterm Maxwell model with six parameters described the stress relaxation behavior of avocado fruit at different compressive loads, ripeness and sizes based on the maximum relative difference (MRD), R2, and residual MSE. The advancing degree of ripeness have a corresponding decrease in the decay stress value (σ1) and time of relaxation (τ1) component of the model. To minimize mechanical damage, avocado should be packed in vertical orientation with cushion (bubble wrap, foam, or paper) and can be stacked up to 10 layers for small size and 12 layers for medium size at harvest using 10 kg capacity cartons.

Citation:

VALENCIA, J., PERALTA, E., YAPTENCO, K., & ESGUERRA, E. (2022). Rheological Properties of Purple Avocado (Persea Americana Mill.) Fruits at Different Ripening Stages. Philippine Journal of Agricultural and Biosystems Engineering, 18(1), 26–40. https://doi.org/10.48196/018.01.2022.03