Oven, Microwave, and Combination Roasting of Peanuts: Comparison of Inactivation of Salmonella Surrogate Enterococcus faecium, Color, Volatiles, Flavor, and Lipid Oxidation

Abstract

Peanut safety and quality were evaluated for different roasting technologies. Shelled raw peanuts were roasted using an oven at 163 to 204 °C, microwave, or oven and microwave combinations. The lethal effect of these treatments was investigated on peanuts inoculated with the Salmonella surrogate, Enterococcus faecium and stored at room temperature for 1 h, 24 h, or 7 d before roasting. Roasted peanut color, odor activity values (OAVs), descriptive sensory panel analysis, free fatty acid, and peroxide values were determined. Color and OAVs were also analyzed on 2 commercial peanut butters. OAVs were calculated using volatile levels quantified with selected ion flow tube mass spectrometry and known odor thresholds. All treatments resulted in a minimum of 3 log reduction of inoculated bacterial population. Resistance to the process was not influenced by storage of inoculated peanuts prior to treatment. Roasting by different methods produced equivalent, commercially ideal L* color. Based on the OAVs, treatments had similar volatiles important to flavor compared to the commercial samples. Descriptive sensory analysis showed no significant difference between the roasting treatments for most of the sensory attributes. Lipid oxidation was not significantly different between the roasting methods, displaying no evidence that roasting time or temperature affected lipid oxidation, when ideal color was produced. These results suggest that oven, microwave, or combination roasting should be sufficient to mitigate the threat of Salmonella contamination and produce similar color, OAVs, sensory attributes, and lipid oxidation results.

Flavor of roasted peanuts ( Arachis hypogaea ) — Part II: Correlation of volatile compounds to sensory characteristics

“…(Sanders et al, 1989). Smith and coworkers, studied the relationship between color and roasting method (microwave, oven and combination of the two), and concluded that peanuts roasted to the same L* value by different methods, showed no significant differences in most sensory attributes (Smith et al, 2014). In our study, using various raw materials but only two processes, the relationship between L* and "roasted peanut" was also significant, but weaker.…”

“…Toluene correlated negatively with the roasted peanut aroma. This compound was previously identified to have a negative effect to roasted and peanut aromas (Smith, Perry, Marshall, Yousef, & Barringer, 2014), but it appears to occur at a subthreshold level. Interestingly, maltol (butterscotch/caramel aroma (FAO, 2015)) correlates highly with roasted peanut aroma.…”

Physicochemical quality and volatile flavor compounds of hot air‐assisted radio frequency roasted almonds

“…Undecane was the most abundant volatile compound of raw and roasted almonds, which constituted approximately 10% of the total compounds. The new volatile compounds in roasted almonds were mainly produced by the Maillard reaction, which synthesized pyrazines and induced Strecker degradation, caramelization of sugars, and lipid oxidation (Smith, Perry, Marshall, Yousef, & Barringer, ). Most of those main classes of volatile compounds are generally regarded as thermal flavors in oily nuts, such as furans and pyrazine compounds.…”

Effect of Roasting and Grinding on the Processing Characteristics and Organoleptic Properties of Sesame Butter

“…To correct for variations in the capacity of the SPME fibres and the sensitivity of the GC‐MS system, 1,2,3‐trichloropropane, which was not found in sesame oil, was used as the internal standard. Volatile compounds included pyrazines, pyrroles, and aldehydes were mainly produced by the Maillard reaction, caramelization of sugars, and lipid oxidation . According to Ho and Shahidi, the other compounds were not considered as chief contributors to the flavor of thermally processed products due to their relatively high odor threshold values.…”