UD students look at possible contamination of irrigation water

November 21, 2013 under CANR News

students look for contaminants in irrigation waterStudents in the University of Delaware College of Agriculture and Natural Resources (CANR) are using a plot of land on the campus farm to help study possible contaminants in soil and irrigation water used to grow leafy greens and tomatoes in order to help inform new regulations on growers that will be going into effect next year as part of the Food Safety Modernization Act.

The study is part of a $9 million U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) Specialty Crops Research Initiative (SCRI) grant titled “Developing Consensus Produce Safety Metrics for Leafy Greens and Tomatoes.” The project is led by the University of Maryland and is taking place at seven different universities and industry liaisons across the country.

Signed into law in 2011 by President Barack Obama, the food safety act has been implemented in stages over the past two years.

Kali Kniel, associate professor of animal and food sciences, explained that part of the law includes regulations for growers of fruits and vegetables, noting that this is the first time there have ever been specific regulations for growing fruits and vegetables.

“There have been guidelines and marketing agreements before but not regulations in terms of environmental aspects that are difficult to control,” Kniel said, “so growers are anxious and nervous about this.”

The rules are not yet finalized and include some fairly complicated aspects in terms of metrics, use of irrigation water and soil amendments. Delaware extension agents have been working with growers over the past two years to make the transition more manageable.

To help inform these regulations, researchers from the seven universities will meet with representatives of the Food and Drug Administration (FDA) to report on their findings.

UD research team

At UD, the research team used a plot of land next to the Allen Laboratory and has been growing tomatoes, romaine lettuce and spinach on the plot for the past two years.

Angela Ferelli, a senior double majoring in biochemistry and food science, worked on the project during the first summer and said that it was interesting to get hands-on experience outside of the lab.

Because it was her first time working in a garden and growing plants for a project, she said that it was a “labor of love. We really wanted to tackle it head on and we didn’t know what the best way was to keep the weeds out and keep the plants growing and happy. And if you looked down the rows the first time we planted, we had four rows — they started out straight and then they went crooked, but you could definitely tell that we were doing it, and it was great.”

Ferelli said that the next year, the group tested a new variable plasticulture for tomatoes, putting down plastic tarps to keep the weeds out. This is also a means of potential control for splash from rainfall for growing produce and for the protection from plant contact with soil.

Patrick Spanninger, a doctoral student in Kniel’s lab who has been working on the project since the beginning, explained that after the students grew the plants, they ran trials by pouring water mixed with manure that contained different levels of E. coli on the plants to monitor bacterial persistence on the fruit. “We wanted to see if the bacteria in the manure that we started with survived after we put it on the plants,” said Spanninger. This is a controlled way modeling how irrigation water may become naturally contaminated in real-life situations.

The students then harvested the tomatoes and leafy greens by hand and used random sampling strategies to look at the levels of generic E. coli on the plants.

Explaining that because the outdoors is a complicated, unsterile environment, Kniel said that they tested for generic E. coli because it is an indicator organism, meaning that if increased levels of generic E. coli show up, there could be a potential risk associated with the irrigation water. This is the current industry standard and part of a grower’s best practices.

The problem with rain

Another part of the research on which the students worked was the development of water safety metrics to help decide how many generic bacteria — nonpathogenic bacteria — can be found in water used for irrigation.

students look for contaminants in rain water“They’re associating the levels of bacteria in the water with climactic changes with rainfall and wind and relative humidity and temperatures to try and understand what puts produce at risk for having higher bacterial levels or potential pathogens,” said Kniel.

Ultimately, Kniel said that rainfall more than anything else poses a problem for growers when it comes to bacterial contamination on fruit that may have originated in irrigation water. Using DNA fingerprint analysis on the recovered E. coli, Spanninger was able to trace bacteria coming from the manure through the tomatoes on different plants.

“We actually are seeing that the initial amounts of generic bacteria in the water are not really the biggest issue. Bacterial decay on plants occurs within a couple of days. Rainfall seems to really affect fresh produce,” Kniel said. “We think that rain close to harvest dates is an important consideration and should be part of a Food Safety Plan, so we’re sharing with the FDA that aspects other than strict water metrics should be considered. At this time meeting the water standards the FDA is suggesting is difficult for produce growers around the country, in particular those that use surface water for irrigation.”

Spanninger agreed with that assessment. “From what we saw, the greatest influence on bacterial presence and persistence was big rain events, which we’ve been getting more of in recent years.” He explained that the research was conducted last fall during Hurricane Sandy and in the summer when the area was doused with a large amount of rainfall.

Spanninger also added that possible contamination from animals — such as geese, dogs, and groundhogs in the field — is another issue that the group is investigating. Wildlife intrusion into produce fields is an important area of study along with irrigation water standards.

In addition to looking for E. coli, the group — along with the research teams at other universities involved in the project — also set out to identify potential hot spots for growers, areas where they would have the most success growing crops without high risk of contamination.

Ferelli explained, “The overarching implications of this research are going to be for the growers to be able to have a better grip on where the risk is in the field. So if a grower goes out now with this risk in mind and he or she see’s there has been a rain event, or observes that an animal has come in and left it’s signature, instead of just taking out that one plant that has been affected, the grower will be better equipped with knowledge to recognize the possibility to section off several plants in that area.’”

Article by Adam Thomas

This article can also be viewed on UDaily.


UD students unveil new food products as part of senior capstone class

May 21, 2013 under CANR News

Edible tape to hold together messy tortillas, non-alcoholic alcohol flavored candies and healthy snack cakes were products developed recently by members of the University of Delaware food science capstone class.

Seniors handed out samples of their food products to members of the University community from 11:30-1 p.m. on Monday, May 13, in the Townsend Hall Commons.

The three student groups — Tortilla Tape, Sober Temptations and Cocoa Jammers — arrived in Townsend to hand out samples and answer any questions visitors had about their semester-long projects.

Putting together the projects was an impressive feat according to Rolf Joerger, associate professor of animal and food sciences, who led the class.

CANR Food Science Capstone class display their products“Three months to develop a new product is a little short but most of the time students manage to complete the task,” explained Joerger. He said each group has to care of all aspects of food product development, including idea generation, recipe development, ingredient acquisition, correct packaging and labeling, and even marketing.

“In the end, it’s supposed to look like a real product,” Joerger said. “For example, on the box, the nutrition label has to be a certain size by law and the package has to have certain pieces of information on it. The students have to look into all of this as far as what they legal requirements are.”

Joerger explained that the three groups had tables set up at Ag Day in order to hand out their products and adjust them according to the feedback they received.

Tortilla Tape

The Tortilla Tape group included food science students Dana Screnci and Lauren Rizzi and Nick Young, a pre-veterinary medicine and animal bioscience major. Their product featured an edible starch-based piece of tape that relies on the adhesive properties of Tylose powder and starch, and is used to bind the tortilla to itself and solve the problem of keeping the actual ingredients inside the tortilla.

Screnci explained that the way the group developed the product was fairly straightforward. “We came up with the idea just by eating a burrito and it falls apart and you need a toothpick, or at the restaurants they have the foil, and we just figured that it would be much easier if there was something they could put on it to keep it together without needing all of the excess materials.”

The group decided — based on the results they got back from surveys — that instead of having flavored or colored tape, most people would prefer to pretend the tape isn’t there.

“As of now, people seem to like that it just blends right in,” said Screnci. She also explained that the group’s idea would be to offer tortilla tape in restaurants as well as in grocery stores.

Sober Temptations

The Sober Temptations group offered non-alcoholic, alcohol-flavored candy. The flavors they handed out were: amaretto sour, blackberry merlot, Belgian golden ale, strawberry ale, pina colada and mojito. The group — made up of Teresa Brodeur, Alyssa Chircus and Angela Ferelli — discovered at Ag Day that certain flavors, especially the blackberry merlot, were more popular than others.

“We got pretty good feedback overall,” said Chircus. “I think we had about 86 percent who said they would actually buy it, so that really fueled us and we made three new flavors within 24 hours.”

Chircus and Brodeur both work at the UDairy Creamery so they were able to use their knowledge and connections to help with their project. “We had a lot of the flavors at the creamery already,” said Brodeur. “My boss was really helpful in letting us test out stuff, and then through the close relationship with them, we had the flavor company already so we could reach out to them and they were willing to send us samples.”

Ferelli explained that their non-alcoholic treats could be served at different sorts of gatherings. “You go to these formal events and you never have anything very sweet, it’s usually very savory. So, we have a great pairing here for any kind of event. We have a range, from elegant and swanky to casual.”

Cocoa Jammers

The Cocoa Jammers group — Amanda Hoffman, Lesley Payonk and Melissa Ehrich — decided to make healthy alternatives to popular snack foods, especially in the wake of uncertainties at Hostess.

“Everyone was really up in arms that they couldn’t get their Twinkies and then we looked up the calories involved in that and how unhealthy that is so our snack cakes have four grams of protein and three grams of fiber,” said Hoffman. “The traditional snack cake has 250 calories while ours only have 90 calories per serving, so it’s less than half. They also have 10 grams of fat while ours have 1.5 grams of fat.”

Hoffman added they had another reason for coming up with a healthy snack cake, as well. “We had a roommate sophomore year who couldn’t eat anything with flour in it so we wanted to come up with a product that tasted good and that was also healthy.”

Article by Adam Thomas

Photos by Christy Mannering

This article can also be viewed on UDaily.