Relationships between optical and textural properties of cold-set whey protein gels

The transition from a clear cold-set whey protein gel (10 mmol/L Ca2+) to a highly aggregated gel (360 mmol/L Ca2+) was studied using a fast responding fibre optic probe. The gels, formed at room temperature by gradually increasing [Ca2+], showed a progressive increase in gel strength measured as penetration force. Fibre optic probe results correlated highly with gel strength data, whereas a conventional surface colour meter was not as useful. The gels' ability to deform (spread oat during compression) decreased with the increase in [Ca2+] and correlated with the probe readings; the surface colour meter provided an r = 0.63. The specific design of the probe that made it sensitive to scattering light was used to explain the differences between the two light measuring apparatuses. Overall, the probe allowed a rapid assessment of the characteristics of cold-set whey protein gel. (C) 1997 Academic Press Limited.