The effect of X-ray irradiation on Salmonella inactivation and sensory quality of almonds and walnuts as a function of water activity.
Summary of "The effect of X-ray irradiation on Salmonella inactivation and sensory quality of almonds and walnuts as a function of water activity."
The overall goal of this study was to develop a set of process design principles for low-energy X-ray irradiation of tree nuts. Almonds and walnuts were inoculated with Salmonella Enteritidis PT30 and Salmonella Tennessee, and conditioned to four different water activities (0.23, 0.45, 0.64, and 0.84 a(w)). Thereafter, the inoculated/conditioned samples were irradiated to achieve up to a 5-log reduction in Salmonella using a pilot scale low-energy X-ray food irradiator. Greater efficacy (D(10)-value: the dose required to eliminate 90% of the microbial population) for inactivating SE PT30 and S. Tennessee was seen on the surface of almonds (0.226-0.431kGy) than on walnuts (0.474-0.930kGy) at all water activities. Also, the efficacy did not change monotonically with water activity. Overall, no significant difference (P>0.05) in sensory characteristics was seen between non-irradiated almonds and those irradiated to achieve a 5 log reduction in Salmonella. However, irradiating walnuts to the dose corresponding to a 5 log reduction caused a perceivable change in flavor. Post-irradiation storage tests revealed that surviving bacterial counts did not change over 120days, regardless of nut type, Salmonella serovar, and a(w). Therefore, low-energy X-ray irradiation technology appears to be a promising non-thermal pasteurization strategy for certain types of nuts.
Biosystems & Agricultural Engineering Department, Michigan State University, East Lansing, MI 48824, USA.
This article was published in the following journal.
Name: International journal of food microbiology
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22189022
- DOI: http://dx.doi.org/10.1016/j.ijfoodmicro.2011.11.028
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Medical and Biotech [MESH] Definitions
Botanically, a type of single-seeded fruit in which the pericarp enclosing the seed is a hard woody shell. In common usage the term is used loosely for any hard, oil-rich kernel. Of those commonly eaten, only hazel, filbert, and chestnut are strictly nuts. Walnuts, pecans, almonds, and coconuts are really drupes. Brazil nuts, pistachios, macadamias, and cashews are really seeds with a hard shell derived from the testa rather than the pericarp.
Irradiation of one half or both halves of the body in the treatment of disseminated cancer or widespread metastases. It is used to treat diffuse metastases in one session as opposed to multiple fields over an extended period. The more frequent treatment modalities are upper hemibody irradiation (UHBI) or lower hemibody irradiation (LHBI). Less common is mid-body irradiation (MBI). In the treatment of both halves of the body sequentially, hemibody irradiation permits radiotherapy of the whole body with larger doses of radiation than could be accomplished with WHOLE-BODY IRRADIATION. It is sometimes called "systemic" hemibody irradiation with reference to its use in widespread cancer or metastases. (P. Rubin et al. Cancer, Vol 55, p2210, 1985)
Viruses whose host is Salmonella. A frequently encountered Salmonella phage is BACTERIOPHAGE P22.
A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.
A serotype of Salmonella enterica which is an etiologic agent of gastroenteritis in man and other animals.