Study establishes instrumental probes for quality control of French fries

By Sally Robertson, B.Sc.Feb 4 2020

French fries are an extremely popular food item in the USA and their texture has been identified as one of the main quality determinants.

Image Credit: Nataliia K, Shutterstock.com

The texture of foods can be evaluated based on human sensory perception and the use of instrumental methods. However, sensory perception is subjective and although sensory analysis is a commonly used method, it requires time-consuming, expensive panel training, as well as demanding reliable reference standards.

Research efforts have focused on improving the objective instrumental methods, which have involved trying to determine the relationship between human sensory perception and instrumental measurement.

This would guide the search for quality assessment instruments, help predict people’s responses to foods, improve understanding of how the texture is perceived and help to optimize techniques for testing the instruments.

“There is still no specific scientific consensus on the choice of probe types”

However, writing in The Journal of Texture Studies, researchers from the National Engineering Research Center for Functional Food in Wuxi, China, say that although the common instrumental texture analysis of fries has been widely used, there is still no specific scientific consensus on the choice of probe types and the correlation between probe types and sensory texture of fries.

“Moreover, little attention has been given to confirm which instrumental tests and probes were suitable for testing the texture of fries and which has the best relationships with the sensory perception of fries,” they add.

Hui Zhang and colleagues have now conducted a study analyzing the relationship between sensory and instrumental data to establish suitable instrumental methods for determining the texture of French fries served in fast-food restaurants.

The present study “will provide the important basic dataset for the quality control of French fries, especially for food manufacturers involved in the specificity related to the texture of French fries,” says the team.

What did the study involve?

The researchers used ten samples of French fries purchased from fast-food restaurants located in Wuxi.

Eight panelists (3 men and 5 women, aged between 22 and 29 years) received eight training sessions lasting about two hours. The training aimed to establish a consensus on descriptive vocabulary and to familiarize the panelists with evaluation methods and an intensity rating scale where sensory attributes are scored from 0 (none) to 10 (high).

The samples were subjected to five commonly used instrumental tests. A compression test was used to inform on hardness, springiness, cohesiveness, chewiness, and resilience; a puncture test assessed hardness and a three-point bending test assessed breaking stress and fracturability.

A Warner-Bratzler Blade with guillotine probe tested toughness and firmness and a cut test with a Volodkevich Bite Jaws probe was used to simulate biting and assess firmness.

What did the study find?

The results showed that the French fries exhibited a wide range of texture, with four having distinct dominant sensory attributes.

Multivariate statistical analysis revealed that the compression test parameters were strongly correlated with the most sensory attributes.

Instrumental parameters derived from the Warner-Bratzler Blade cut test with guillotine probe showed a significant positive correlation with sensory crispiness and hardness, while parameters derived from the puncture test were significantly correlated with sensory chewiness.

Among these instrumental methods, compression, blade with guillotine probe and puncture test are recommended for texture measuring of French fries. These results will provide a time-saving and efficient method for determining the texture of French fries,”

Zhang and colleagues

The team says their study results could play an important role in the quality control of fries, particularly in the context of managing fast-food restaurants.