Crumbliness - defined as the extent and the ease by which a food falls apart on compression in the mouth - is a desirable attribute in a range of products, particularly cheese, processed meat and confectionery. Since it often affects consumer acceptance, it is used as a measure for quality control in manufacturing.
Researchers from the Wageningen Centre for Food Scientists and Nizo Food Research set out to examine the relationship between crumbliness and gels' physical and structural properties. Their aim was to facilitate the control and engineering of this property.
They believe their report, published online ahead of print in the journal Food Hydrocolloids (Elsevier) this week, is the first time this relationship has been examined.
Led by Ladislava van den Berg, the researchers obtained samples of commercially available ingredients: Whey protein isolate (WPI), glucono-d-lactone, vitamin C, gellan gum, locust bean gum, ?-carrageenan, GSK-carrageena, and a high methyl pectin. These were used to prepare WPI aggregates and polysaccharide stock solutions.
The gels were then subjected to a number of tests, including a uniaxial compression, a wedge test to determine critical speed for fracture, and a compression-decompresison test.
Observations were made using confocal laser scanning microscope, and quantitive descriptive analysis using 17 mouthfeel attributes.
The researchers found a strong association between the crumbly properties of the WPI and WPI mixed gels are strongly related to breakdown mechanisms - which in turn are dependent on their viscoelastic properties.
These properties come about as a result of the balance between elastically stored energy and energy dissipation during formation (stored energy being determined as a percentage of recoverable energy in a compression-decompression test).
The most crumbly gels were found to be those that break readily via a free-running crack - that is, with high recoverable energy. The least crumbly gels were seen to have slow, yielding-like breakdown.
Crumbliness was also seen to be affected by serum released from the gels, which contributed to energy dissipation. Serum release was seen t be affected by the gel's microstructure.
"It is of importance to study these associations as it gives an opportunity for engineering materials with desired physical as well as sensorial properties," wrote the researchers.
Source: Food Hydrocolloids
DOI: 10.1016/j.foodhyd.2007.08.006
Title: Energy storage controls crumbly perception in whey proteins/polysaccharide mixed gels
Authors: L van den Berg, AL Carolas, T van Vliet, E van
der Linden, MAJS van Boekel, F van de Velde
