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Heat-resistant spores on a dry, heat-and water-sensitive food matrix are difficult to inactivate. Radioactive or X-ray exposure is allowed and accepted only for some selected commodities. Non-thermal atmospheric pressure plasma treatments could offer an efficient, fast, and chemical-free solution. The effectiveness of direct contact cold atmospheric plasma (CAP) generated by a dielectric barrier discharge (DBD) device and air as process gas was evaluated against spores of Bacillus spp., Geobacillus spp., and Penicillium spp. A maximum of 3 log 10 cycles of inactivation was achieved for B. coagulans spores exposed for only 10 s at low surface energy of 0.18 W/cm 2 determined directly at the electrodes. This corresponds to an initial decimal reduction time of D 1 = 0.1 min. Spores of B. subtilis are the most resistant amongst the studied strains (D 1 = 1.4 min). The determining parameter in the modeling of the inactivation curve is surface energy. Non-porous, native starch granules or shells from diatoms, a highly porous material, were also contaminated with spores and treated by DBD CAP. The inactivation level was significantly reduced by the presence of powders. Considering plasma diagnostics, it can be concluded that the spore shell is the primary and main target for a plasma-induced inactivation. The inactivation affect scales with surface energy and can be controlled directly via process time and/or discharge power.

Background: The study of aroma release has gained popularity in food science. Nowadays, experiments become increasingly more complex. However, an application of theories on mass transfer, which may help to better explain the results, is lagging behind on these developments. Scope and approach: The goal of this review is to get together, in a concise way, the state of the art on fundamental knowledge of mass transfer in aroma release plus creating an extension of theory with a comprehensible classification that is useful for food scientists. The existing mathematical model is simplified and points that have received little attention are identified. Key findings and conclusions: An overview of experimental studies that focus on the influence of viscosity on aroma release show that there is heterogeneity in results and no consensus exists on the influence of viscosity. Such heterogeneity may be better understood with the effects of mass transfer. These effects are summarized by describing three implications based on non-proportional relationships between the partition coefficient and (A) the overall mass transfer coefficient, (B) the depletion and saturation timescales , and (C) the peak value of the aroma concentration in the head space. A classification scheme is made to enable food scientists and technologists to apply the complex description in shorter and simpler terms that can be communicated and compared more easily. The scheme depends on a classification in two dimensions based on a thermodynamic factor, the partition coefficient, and a kinetic factor which divides aroma's and experiments into four different classes.

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