Infrared Heating for Improved Safety and Processing Efficiency of Dry-Roasted Almonds

The use of infrared (IR) heating technology was investigated for improving safety and processing efficiency of dry-roasted almonds. Almonds were roasted at 130, 140 and 150C with three different methods: IR heating, sequential infrared and hot air (SIRHA) heating, and traditional hot air (HA) heating. The heating rate and color change of almonds under different heating methods and temperatures were evaluated. The value of overall color change was used as the indicator of degree of roasting. Pediococcus sp. NRRL B-2354 was used as a surrogate for Salmonella Enteriditis PT 30 and inoculated onto raw almonds for evaluating the pasteurization efficacy of different processing methods and conditions. When SIRHA roasting was used to produce medium roasted almonds, 4.10-, 5.82- and 6.96-log bacterial reductions were achieved with 130, 140 and 150C roasting temperatures and roasting times of 21, 11 and 5 min, respectively. Under those conditions, the SIRHA roasting process resulted in 38%, 39% and 62% time saving compared to traditional HA roasting at the same corresponding roasting temperatures. We concluded that SIRHA roasting is a superior roasting method for the production of roasted almonds that meets the pasteurization requirement and has the potential to reduce costs due to reduced roasting time compared to current hot air roasting.