Quality and mold control of enriched white bread by combined radio frequency and hot air treatment

0260-8774/$ see front matter 2010 Elsevier Ltd. A doi:10.1016/j.jfoodeng.2010.11.019 ⇑ Corresponding author. Tel.: +1 509 335 2140; fax E-mail address: [email protected] (J. Tang). This study explored the application of radio frequency (RF) energy in conjunctionwith conventional hot air treatment to provide uniformheating for control ofmold in pre-packaged bread loaf. A 6 kW, 27.12 MHzRF system was used to develop treatment protocols. The treatment parameters were selected based on minimum time–temperature conditions that were required for 4-log reduction of Penicillium citrinum spores while yielding acceptable bread quality. During combined RF andhot air treatments, the core and periphery of the bread loaf were heated together with almost the same heating rate. The maximum temperature difference within one bread slice was less than 5 C. The moisture contents and water activities of RF treated samples first increased and then decreased compared to those of untreated samples, while firmness increased during the storage for bothheat treated anduntreated samples, yet theoverall differences in sample qualities between RF treated bread samples and control were not significant. Because of better heating uniformity,much lowermeanproduct temperature and shorter holding timewereused for control ofP. citrinum spores with combined RF and hot air treatment as compared to conventional heating alone. Heating bread to58 Corhigher resulted in4-log reduction ofP. citrinum spores isolated frommoldybread. The storage life at room temperature (23 C) was extended by 28 ± 2 days for the treated white bread. 2010 Elsevier Ltd. All rights reserved.