S294: Quality and Safety of Fresh-cut Vegetables and Fruits
Statement of Issues and JustificationConsumption of fresh-cut produce increased at an annual rate of approximately 10% from 1995 to 2004 (UFPA, 2004) and the market for fresh-cut vegetables and fruits is estimated at $10-12 billion annually (UFPA, 2010). It is estimated that fresh-cut products currently make up more than 15% of all fresh produce marketed in the U.S (UFPA, 2010). Postharvest losses of fresh-cut produce are difficult to estimate but given the highly perishable nature of fresh-cuts compared to intact produce, the retail value of fresh-cut produce losses may exceed $1 billion annually.
The appearance, convenience, and generally high nutritive value of fresh-cut vegetables and fruits drive sales of fresh produce, but repeat sales of the fresh-cuts is dependent upon assurance of its safety and the products having pleasing texture and flavor. The industry primarily relies on established technologies derived mainly from practical experience to maintain visual quality and shelf-life with less consideration of the quality characteristics that drive repeat sales such as good flavor retention, maintenance of an appealing texture (crispness, crunchiness), and increased microbial quality leading to extended shelf stability and food safety. Through interaction with the industry we know that current technologies, especially for fresh-cut fruits, do not provide the shelf stability needed to supply long distance domestic markets with optimum flavor quality.
As a result of physiological and microbial deterioration occurring during storage and marketing of fresh produce, and especially fresh-cut produce, there is a need to develop effective, non-damaging treatments for maintaining the quality (appearance, flavor, texture, nutritional value) and food safety of fresh harvested produce (How, 1990). Most of the sales of fresh-cut produce have been in the vegetable (salad, carrot slice) area (Garrett, 2002) and commercial handling practices for fresh-cut vegetables have been described (Barth et al., 2004). Beginning about a decade ago, research and commercial interest has focused more on fresh-cut fruits and melons (Bai et al., 2004; Beaulieu et al., 2004; Beaulieu and Gorny, 2004; Beaulieu and Lancaster, 2007; Beaulieu and Lea, 2007; Bett-Garber et al., 2003; Dea et al., 2010; Kader, 2008; Plotto et al., 2010; Rojas-Grau and Martin-Belloso, 2008; Saftner et al., 2003; Soliva-Fortuny and Martin-Belloso, 2003). With over 200 different vegetable and fruit crops with potential for development as fresh-cut products, each with unique physiology and handling requirements, an integrated, scientific approach to research and development including microbiological interactions with these products is critically needed.
The conditions on the cut surface of fresh-cut products, with the presence of water and compounds that microbes can use for nutrition, provide ideal conditions for growth of microbes. Unfortunately, as produce consumption has increased in the U.S. in recent years, so has the number of produce-related outbreaks of foodborne illness. Produce-related outbreaks accounted for 12.3% of all reported foodborne outbreaks from 1990 to 2007, compared to only 0.7% in the 1970s (AFF, 2010, Sivapalasingam et al., 2004). About 23% of all foodborne illnesses from 1998 to 2007 were due to fresh produce (CSPI, 2009). Between 1996 and 2008, lettuce/leafy greens (32.9%), tomatoes (17.1%), and melons (15.9%) comprised two-thirds of produce-related outbreaks: (Gravani 2009). Pathogens of primary concern are E. coli O157:H7, Salmonella, L. monocytogenes, and Norwalk-like viruses. From 1996 to 2006, 72 foodborne illness outbreaks were associated with fresh produce consumption with 18 of these connected to fresh-cut produce (FDA 2008). The economic yearly losses due to acute foodborne illness are estimated to be $152 billion, with $39 billion of this loss associated with fresh, processed, and canned produce (Scharff 2010). The continuing nature of such produce-related outbreaks represents a threat to further increases in per capita consumption due to lowered confidence in the microbial safety of the product by the consuming public. Such outbreaks can also be very costly to growers, processors, shippers and restaurants.
It is very difficult to ascertain the efficacy of control measures for food safety as there are no direct measures of the effectiveness of intervention strategies on the rate of occurrence of foodborne illness in the general population. Instead, model systems are used to test the effectiveness of intervention strategies at selected stages of the processing chain. The hope is that by identifying and implementing numerous control strategies along the processing chain that were found to be effective in model systems, that the resulting net risk reduction will effectively reduce the real risk of foodborne illness. There are a number of opportunities to address food safety concerns as part of this project. Quality and safety concerns often overlap. For example, efforts to reduce spoilage organisms should also impact pathogenic organisms, and removing damaged produce prior to production will reduce the risks associated with pathogen colonization of wounds.
The Food & Drug Administration (FDA) in collaboration with the USDA and the Centers for Disease Control (CDC) issued a series of guidelines in 1998 (since updated) referred as Good Agricultural Practices (GAPs) to reduce the risk of foodborne diseases from fresh fruits and vegetables (U.S. FDA, 2008). Since that time, indicative of the importance of fresh fruit and vegetable food safety and security research, USDA has emphasized the enhancement of safety and security in its strategic planning and created the Food Safety and Quality National Education Initiative (FSQ), Special Research Grants for Food Safety, the Food Safety Institute of the Americas, and currently the National Food Integrated Safety Initiative. Members of S294 have been actively involved in all of these programs and many also are involved in extension food safety programs.
In order to ascertain food safety risks involving fresh and fresh-cut produce, it is critical to be able to determine the survival and persistence of viable or infectious human pathogens under environmental conditions occurring in produce handling and processing facilities, on harvested crops, and on intact or fresh-cut products. Therefore, methods for detection and enumeration of target microbes, including bacteria and viruses, are of core relevancy to this project. Approaches for detection and enumeration of microbes on fresh produce can play an important role in mitigation of fresh produce-associated spoilage or foodborne disease, as well, providing decision makers with timely and actionable data, especially on the presence of human pathogens in these products (Brehm-Stecher et al., 2009). These data could help guide interventions such as: refusal of contaminated product from the field, cessation of processing for line or equipment sanitation, destruction of contaminated product held in inventory pending testing results, or product recall. Due to the relatively short shelf lives of most types of fresh produce, rapid methods for detection and enumeration are of special relevance to the goals of this work.
Integration of physiological, pathological, food safety, and instrumental and sensory quality measurement concepts is essential for developing the most effective handling procedures and innovative, new technologies for maintaining quality and shelf stability of fresh-cut products. Much experimental work is needed to optimize and integrate new and emerging treatments in diverse fresh-cut products. This fact supports the proposed integrated approach of having parallel projects in different states and of focusing the research into specific areas of importance. Alternative and emerging technologies for maintaining the quality and shelf stability of fresh-cut produce are being introduced at a rate that often precludes thorough evaluation of instrumental and sensory quality attributes, and their impact on product nutritional value, microbial quality and food safety. To do so, a multidisciplinary approach as proposed herein also will be needed to optimize the new and emerging treatments.
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