Texture is a critical quality attribute to all fruits and vegetables, whether it is to assess ripeness of the raw item or functional performance in their processed forms. Evaluating the texture of fruits and 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:
These are all now commonly associated as the norm for the acceptable state, feel and taste of these foods.
If a strawberry 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.
The inclusion of fruits and vegetables in processed products; categorised as vegan, vegetarian or plant-based, requires that the processor must provide a quality texture from a formulation with specific and restricted ingredients. Often these foodstuffs are substitutes, and as such must be tested to closely replicate a desired mouth-feel akin to another type of food source.
Fruits and vegetables differ significantly in texture between one another, therefore a range of texture test techniques are available in which to accurately assess their characteristics. Common consumer sensory texture descriptions, especially fresh produce, are:
These characteristics can be measured and compared throughout production and processing to assess the changes in texture. Different varieties of the same type of fruit or vegetable, for example, pears, can be easily examined to determine differences in texture. Pea texture for harvest is a specialised field, which requires a tenderometer.
Deformation tests using compression platens (ideally larger than the deformed sample) are useful for assessing the integrity of cooked potatoes. Squashing solid and self-supporting samples enables a number of textural properties to be evaluated, including hardness, springiness and fracturability.
Use back extrusion to measure flow and spoonability of thick purees and fruit pulps.
Small cylinders, balls, needles and cones are used to penetrate into a sample’s surface imitating biting in the mouth. This evaluates the ripeness and cook quality of fruits and vegetables by determining their firmness.
Multiple point analysis of jam allows for different particulates when measuring set firmness. Used to test multiple points on one sample where texture and form may vary considerably from one area to the next to measure properties such as firmness, gel strength and maturity. Application examples include:
Measuring flexure properties using a three point bend determines freshness and crispness of vegetables, such as asparagus.