The science of texture analysis in recent years has undergone considerable development to facilitate its practical application within the factory environment. Jon Hellyer reports.
To maximise the practical benefits of texture studies to both the development department and the factory itself it is essential that methods developed are: accurate, reliable and reproducible. It is only when these three criteria are met that texture methods can be practically and constructively implemented within the non-expert factory environment where time is of the essence.
Based on principles developed at CCFRA, CNS Farnell has been asked by a number of key commercial clients to facilitate the transfer of texture testing protocols into the commercial environment.
Focussing on the assessment of breadcrumb texture, the customers core requirements were firstly established. It was critical not to over complicate the evaluation, but focus on characteristics deemed critical to the quality of the finished loaf. Based on the long established principles of texture profile analysis (TPA) textural parameters were extracted from standardised force-deformation traces (Fig.1), eg evaluation of significant events occurring during both compression and decompression cycles of the QTS25 Texture Analyser.
Parameters considered of core interest in relation to breadcrumb quality, as determined through sensorial correlation and most importantly practical value are:
* Cohesiveness. Ratio of energy input by the instrument to deform the sample. Representative of how the sample holds together thus is an indicator of internal bond strength eg acts as an indicator of visco-elasticity where ratio values close to 1 demonstrate complete elastic recovery and improved sample afreshness'.
* Springiness. Height that the food recovers between the end of the first compression cycle and the start of the second. Representative of how the sample springs back to its original shape in the hand.
* Hardness. Peak force from first compression cycle. Load resistance of the sample to deformation imposed in hand eg how firm the sample felt.
In general the characteristics of Springiness and Hardness are relatively straightforward to practically interpret in relation to product characteristics. Cohesiveness however, is a slightly more complicated parameter to visualise. The parameter of cohesiveness was practically applied within the factory to demonstrate the effect of breadcrumb staling in relation to its sensorial interpretation. For example, as the bread becomes stale water is lost and the product gradually feels less moist and feels drier in the mouth. In addition, as staling progresses the bread breaks down much quicker during mastication.
True understanding of instrumentally measured textural characteristics and the stream lining of methods imposed means that objective measures can be utilised within industry to provide areal' commercial benefits. The instrumental technique discussed provides the customer with an accurate and reproducible means to quantify those small differences between samples, not usually detectable with traditional subjective procedures applied in the factory QC department.
enquiry no 39
Jon Hellyer is with CNS Farnell, Borehamwood, Hertfordshire, England. www.TextureAnalysis.com
