Thermal Inactivation of Salmonella Enteritidis PT 30 in Almond Kernels as Influenced by Water Activity

• Published in: Journal of food protection Vol. 76; no. 1; pp. 26 - 32
• Main Authors: Wang, Shojin, Villa-Rojas, Rossana, Tang, Juming, Gao, Mengxiang, Kang, Dong-Hyun, May, Jae-Hyung, Gray, Peter, Sosa-Morales, Maria Elena, López-Malo, Aurelio
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association for Food Protection 2013; Elsevier Limited
• Subjects: almonds; Aluminum; analysis; Bacteria; Bacteriophage Typing; Biological and medical sciences; Colony Count, Microbial; Consumer Product Safety; Cultivars; Disease Outbreaks; E coli; epidemiology; etiology; flour; Food; Food Contamination; Food Contamination - analysis; Food Handling; Food Handling - methods; Food industries; food industry; Food Microbiology; Food Safety; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; growth & development; Heat; heat inactivation; Heating; Hot Temperature; Humans; Inactivation; Kinetics; Low temperature; metabolism; methods; microbiology; Microorganisms; Models, Biological; Moisture; Moisture content; Nuts; Pasteurization; pathogens; Population; prevention & control; product quality; Prunus; Prunus - microbiology; Prunus dulcis; Risk Factors; Salmonella; Salmonella Enteritidis; Salmonella enteritidis - growth & development; Salmonella enteritidis - metabolism; Salmonella Food Poisoning; Salmonella Food Poisoning - epidemiology; Salmonella Food Poisoning - etiology; Salmonella Food Poisoning - prevention & control; salmonellosis; scalding; seeds; temperature; washing; Water; Water - metabolism; water activity; water content; Salmonella enteritidis; Nuts; Almond; Water activity; Bacteria; Inactivation; Enterobacteriaceae
• ISSN: 0362-028X; 1944-9097; 1944-9097
• DOI: 10.4315/0362-028X.JFP-11-509

Salmonellosis outbreaks related to consumption of raw almonds have encouraged the scientific community to study the inactivation kinetics of pathogens in this dry commodity. However, the low moisture content of the product presents a challenge for thermal control, because the time required to achieve the desired thermal inactivation of microorganisms increases sharply with reduced moisture content and water activity. In this study, we explored and modeled the heat inactivation of Salmonella enterica serovar Enteritidis PT 30 in almond cultivar 'Nonpareil' kernel flour at four water activity (a(w)) values (0.601, 0.720, 0.888, and 0.946) using four temperatures for each aw. The results showed that the inactivation was well fitted by both Weibull distribution (R2 = 0.93 to 1.00) and first-order kinetics (R2 = 0.82 to 0.96). At higher aw values, the rate of inactivation increased and less time was needed to achieve the required population reduction. These results suggest that, to avoid deterioration of product quality, shorter process times at lower temperatures may be used to achieve desired inactivation levels of Salmonella Enteritidis PT 30 by simply increasing the moisture content of almonds. These goals could be achieved with the use of existing procedures already practiced by the food industry, such as washing or prewetting scalding before heat inactivation.