Feasibility of using sequential infrared and hot air for almond drying and inactivation of Enterococcus faecium NRRL B-2354

This study was aimed to develop a sequential infrared and hot air (SIRHA) drying method for whole almonds and evaluate its effectiveness on decontamination of almonds. Wet almonds with hull and shell were dried using different time-combinations of infrared (IR) radiation and hot air (HA) to determine the optimum drying conditions. Almonds were inoculated with Enterococcus faecium, a surrogate for Salmonella enterica. The SIRHA drying (1h IR at 70 °C and 2h HA) reduced the moisture content of almonds to 7% in 3 h, with a saving of 2 h (40%) of drying time compared with HA drying alone. The population sizes of E. faecium showed the largest size reductions of 4.69 ± 0.71, 1.82 ± 0.39, 1.52 ± 0.31 log CFU/nut on hulls, shells and kernels, respectively, after SIRHA drying combined with tempering (T) (2h IR with 2h T and 1h HA). The peroxide value and free fatty acids content of almond oil samples from all drying treatments were within accepted level for the almond industry.