Measuring Vegetable Texture and Vegetable Product Quality

From the point of view of texture, vegetables represent a very diverse group of products. They can be consumed in many different textural forms.

For instance, cooked asparagus is soft, fibrous and pulpy, cucumber is crisp, firm and juicy, raw carrots are hard and crisp, and cooked peas are soft and mealy. The tissue structure in each case determines the texture as received by the consumer.

For many types of vegetables, consumer acceptance of the product is decisively influenced by the vegetable’s texture, along with other qualities such as colour, smell and taste. Texture is a critical quality attribute to all vegetables, whether it is to assess ripeness or functional performance in their processed forms.

From a textural standpoint, vegetables can be divided into several categories:

1: Those that are eaten raw and valued primarily for their crispness, such as radishes and lettuce. These products lose their firm and crisp texture on heating because of loss of turgor and cannot be fully preserved by canning (involving a heat sterilisation step) or freezing (involving blanching, an enzyme inactivation heating pretreatment). Some, such as cucumbers, are preserved by brining/fermentation and turned into a crisp new pickled product.

2: Those that are eaten cooked and valued for their softness/mealiness, such as aubergines and potatoes.

3: Those that can be consumed in either form, such as carrots and cauliflower. These vegetables have relatively thick cell walls that provide rigidity and crispness in the absence of turgor.

Evaluating the texture of vegetables, whether fresh or after post-harvest treatments and processing, shows there is a clear link between the anticipated texture of these food products and their quality. If a vegetable is too soft, it is no longer desirable; therefore sensory characteristics must be continually evaluated to monitor quality standards in order to, for example, establish the optimum time to pick the best crop and produce a consistently good finished product.

Rheological and textural properties of vegetables are studied and monitored for the following objectives:

• Characterising ripeness and its dependence on harvesting conditions, industrial storage, and post-ripening

• Determining correlations between rheological and sensory properties

• Determining deformation behaviour during sorting, transport, processing, and marketing processes.

Texture measurement provides the solution by putting values to traditionally subjective characteristics of foods. Using mechanical means, through the use of a Texture Analyser and an appropriate probe or fixture, it is possible to imitate the actions undertaken by a person when handling or consuming the product to measure typical attributes such as: crispness, hardness, firmness, toughness, softness, flexibility.

Being a natural product, vegetables differ significantly in texture between one another due to their inherent variability. A range of texture methods are therefore available to optimise the repeatability of any texture measurement.

There is a Texture Analysis test for virtually any physical property. Contact Stable Micro Systems today to learn more about our full range of solutions.

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For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

No-one understands texture analysis like we do!

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