Pulsed light inactivation of Salmonella on the surface of almonds and whole black peppercorn
| Author(s) | Liu, Xuanjing | |
| Date Accessioned | 2020-02-13T13:08:55Z | |
| Date Available | 2020-02-13T13:08:55Z | |
| Publication Date | 2019 | |
| SWORD Update | 2020-02-03T13:23:50Z | |
| Abstract | A shaker-assisted Pulsed Light (PL) process was developed to investigate the effectiveness of PL technology on the inactivation of Salmonella on the surface of almonds and whole black peppercorn as well as to examine the quality of treated products by weight and color parameters, and fatty acid analysis. Almonds and black peppercorn inoculated with a cocktail of four nalidixic-acid-resistant strains of Salmonella enterica were treated with PL directly or covered with a quartz plate during PL processing for 2-30 min. Weight before and after treatment was recorded and color measured using a colorimeter with traditional L, a, and b values. When dry almonds were exposed to ultraviolet and pulsed light at 29 mW/cm2 for 30 min and 0.26J/cm2 for 3 min respectively, obvious surface discoloration were observed. Dipping the almonds in water for 1 min once or twice prior to light exposure resulted in a reduction in Salmonella by 5 log reduction at medium intensity. The medium and low intensity better preserved surface color but required longer time for inactivation on Salmonella. In addition, steam-assisted pulsed light treatments were carried by covering stainless pans with a quartz plate. This PL treatment achieved 4.78 log reduction in Salmonella when the light intensity was 0.25 J/cm2 for 10 min on small-scale study. Since the treatment resulted in a temperature over 100℃ that caused some negative effect on almond quality, temperature cycling was performed to achieve over 5 log reduction of Salmonella between 80℃ and 90℃ after 10 min PL treatment with favorable color and weight parameters for small-scale almond. For whole black peppercorn, controlling the temperature (55-80℃) at medium intensity in the steam-assisted system was the most desirable combination since the quality of black peppercorn was significantly better than high intensity treatment. ☐ Thus, steam-assisted PL at medium intensity in combination with temperature cycling could lower the risk of Salmonella contamination during low-moisture food processing. This treatment is a non-chemical means of pasteurization that is effective and more environmentally friendly than dry roasting, blanching, steam and propylene oxide (PPO) for almond products, or steam, chemical treatment, gamma irradiation, chemical and microwave sterilization and pressure sterilization for peppercorn. | en_US |
| Advisor | Chen, Haiqiang | |
| Degree | M.S. | |
| Department | University of Delaware, Department of Animal and Food Sciences | |
| Unique Identifier | 1140445879 | |
| URL | http://udspace.udel.edu/handle/19716/25006 | |
| Language | en | |
| Publisher | University of Delaware | en_US |
| URI | https://search.proquest.com/docview/2308668925?accountid=10457 | |
| Title | Pulsed light inactivation of Salmonella on the surface of almonds and whole black peppercorn | en_US |
| Type | Thesis | en_US |