Determination of the Organoleptic Quality of Hard Dough Biscuits during the Shelf Life by Chemical Analysis

The variations of moisture, pH, free fatty acids (FFA), peroxide value (PV), total carbonyl content (TCC) and organoleptic properties of hard dough biscuits packed with double laminated wrapper, were studied for 56 days of storage under accelerated shelf life conditions at 400C and 90% relative humidity. Variations of FFA, PV and TCC were statistically analyzed using V-masks with time-weighted CUSUM control charts. Sensory test results revealed that the biscuits began to deviate from the organoleptic freshness from 22ndday. Moisture content and FFA gradually increased and pH value slightly declined. The PV and TCC were remarkably elevated during the study. Only the variation of PV was statistically significant on 22nd day which was compatible with the sensorily decay of freshness in biscuits from the 22ndday onwards. However, PV declined after 42ndday onwards while showing a compatible increment in TCC. Either PV >=1.07meq/kg or TCC >=0.25ppm were identified as the indicators of deviation from organoleptic freshness. Thus, the typical hard dough biscuits were considered to be organoleptically fresh when both PV and TCC remained <1.07meq/kg and<0.25ppm respectively. Accordingly, a color scale was developed to efficiently measure the TCC in typical hard dough biscuits.