Spectral Properties and Effect of Drying Temperature on Almonds with Concealed Damage

The feasibility of using near infrared light transmission, obtained after drying, to predict if an almond would develop concealed damage after roasting was studied. It was observed that, after drying, nuts with concealed damage have less absorbance in the oil absorption band at 930 nm and increased absorbance in the region between 700 and 750 nm. From near infrared transmission spectra obtained after drying, discriminant analysis was used to classify nuts as concealed damaged or undamaged; validation classification error rates as low as 12.4% were obtained. The effect of drying temperature, and moisture exposure, on the incidence of almonds with concealed damage was also studied. The use of a lower temperature drying treatment can reduce the incidence of concealed damage. The incidence of concealed damage for nuts receiving the same moisture treatment was 44.4 and 1.2% when dried at 110 and 55 °C, respectively.