Analysis of a decontamination method using ultraviolet light to inactivate Salmonella on alfalfa sprouts
Date
2023
Authors
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Publisher
University of Delaware
Abstract
Alfalfa is a flowering perennial legume crop that is universally grown and consumed by people and animals and has a wide array of uses. For animals, it is usually incorporated into the feed of animals to add nutritional benefits. However, people tend to consume the sprout of this legume plant and use them as an additive to their meal. Alfalfa sprouts have been shown to be a good source of vitamins and minerals when consumed raw (USDA, 2019) and have the ability to reduce the content of several anti-nutritional components that cause digestive issues (Doblado, 2007). Sprouts can be purchased at grocery stores or local supermarkets. However, some consumers like to grow sprouts in their home because they falsely believe that growing their sprouts in their house will significantly minimize their risk of contracting a foodborne illness (Oregon Public Health Division, 2022). ☐ There have been numerous foodborne outbreaks associated with sprout-related products due to the tendency for consumers to eat their sprouts raw. From 2000 to 2020, there have been a total of 53 sprout-related outbreaks. These have resulted in about 1,500 illnesses, 180 hospitalizations, and 5 deaths in the United States alone (CDC, 2022). Out of all these outbreaks, Salmonella, a motile, aerobic, non-spore forming bacteria, has been responsible for causing about 70% of the outbreaks (Gensheimer and Gubernot, 2016). When ingested, Salmonella can cause headaches, nausea, diarrhea, and/or vomiting in the victim. Because of this, we have selected it for the model organism in this study. ☐ To create a processing technology for alfalfa sprout products, three important criteria needed to be met: 1) it is safe for the consumer to do, 2) it is cost-effective for the consumer, and 3) it is easily accessible. After careful consideration, we selected ultraviolet light (UV-C) irradiation for our study. Due to the pandemic, UV machines have seen an uptick in sales. Therefore, we can assume that this technology is easily accessible to the consumer. UV lights are energy efficient to operate and, as long as the unit is operated properly, is safer for the consumer compared to traditional methods. ☐ To see if a greater log reduction can be achieved, we selected two additives for this study that meet the above criteria. Chlorine is a common household sanitizer that is used to disinfect fresh produce in an industrial setting, especially for romaine lettuce disinfection. However, it has been shown that chlorine can leave residues on the surfaces of produce washed with it. Therefore, we have selected white vinegar as our second additive to see if white vinegar can be substituted for chlorine as an effective wash-water additive. White vinegar is commonly used to descale surfaces and as a pickling agent in the food industry. It has also been shown in numerous studies to be effective against certain pathogens. ☐ The goal of this study is to create a decontamination process for alfalfa sprouts using ultraviolet light irradiation and hurdle technologies that consumers can easily conduct from their homes. This experiment used both a small-scale and large-scale UV machine to assess the effectiveness of our treatment method, whether the use of hurdle technologies significantly increase the log reductions, and whether the sensory qualities of the samples will be affected from the treatment. Salmonella was chosen as the bacteria model for this project because it is the more resistant foodborne pathogenin sprout-related products (Newell et al., 2010). If Salmonella can be inactivated from our treatments, we can assume other pathogens more vulnerable than Salmonella can also be inactivated. ☐ Overall, we have found that treating 50 grams of alfalfa sprouts for 5 minutes at 150 RPM is ideal for achieving at least a 3-log reduction of Salmonella. When hurdle technologies are applied, there was at least a 1-log reduction in some cases. When comparing white vinegar to chlorine, white vinegar performed just as well as chlorine with little to no damage to the sensory quality of the sprouts. Because of this, we can safely assure that white vinegar can be used as a substitute for chlorine.
Description
Keywords
Alfalfa sprouts, Salmonella, Ultraviolet light, Flowering perennial legume, Alfalfa sprout products, Ultraviolet light irradiation