Posts Tagged: produce
Why does my pesto turn brown?
I don’t know if plant scientists make better chefs, but knowledge of plant science can certainly improve our cooking. Take, for example, understanding how to handle oxidation, the interaction between oxygen molecules and all the many substances they may contact. Oxidation is what makes your fender rust and your copper penny turn green. As it relates to plants, oxidation is what causes fresh-cut produce to turn brown and wine to lose its flavor when left too long in an open bottle.
Perhaps you know how to thwart oxidation when preparing potatoes and serving sliced apples (and if not, we’ll get to that in a minute) but here is a less-common food that often falls victim to oxidation: pesto. Has this happened to you? You gather an armload of picture-perfect basil, blend it together with olive oil, pine nuts, garlic and cheese and produce a fantastic pesto sauce for your spaghetti. Fresh from the blender, it’s as green as your holiday tree. But by the time you serve it an hour later, it’s a dull shade of olive brown and has lost much of its taste. Oxidation strikes again.
Here’s a handy plant-science trick: Blanche your basil. Heat destroys the enzymes that cause oxidation and the resulting discoloration. Drop your fresh basil in a pot of boiling water for a few seconds and then shock it in a bowl of ice water. Dry it completely, proceed with your favorite recipe and your pesto will stay green and tasty for days. Here’s the recipe I like to use:
- 2 cups packed fresh basil leaves
- 2 cloves garlic
- 1/4 cup pine nuts (I use walnuts when I don’t have pine nuts)
- 2/3 cup extra-virgin olive oil, divided (for special treat, try using a UC Davis olive oil
- Salt and pepper, to taste
- 1/2 cup parmesan or other hard cheese
Combine the basil, garlic and nuts in a food processor or blender and pulse until coarsely chopped. Add 1/2 cup of the oil and process until fully incorporated and smooth. Season with salt and pepper.
If you’re eating it right away, add all the remaining oil and pulse until smooth. Transfer the pesto to a large serving bowl and mix in the cheese. Yum! If you’re freezing it (up to three months), transfer to an air-tight container and drizzle remaining oil over the top. Thaw and stir in cheese.
You can learn more about handling fresh-cut produce at the UC Davis Postharvest Technology Center and explore the joys of plant science at the UC Davis Department of Plant Sciences website.
The more you know, the more careful you are
With a daughter soon to complete a degree in health safety, discussions of Salmonella, E. coli and the like sometimes arise as we sit around the dinner table. As an agriculturally focused family, we like to think we’re pretty savvy about the best way to handle our produce to keep it safe and tasty.
Some are very concerned about food safety. A gentleman phoned the Postharvest Technology Center a few months ago, and shared that he was very concerned about eating strawberries. He thought perhaps he should scrub each one with a soft toothbrush, and then soak them in a diluted chlorine bath.
Others are much less aware of food safety concerns, sometimes using cutting boards and knives interchangeably between raw meat and produce items, or other unsafe food handling practices.
Dr. Roberta Cook, a marketing and postharvest specialist affiliated with the center reported, “in 2008, 53 percent of shoppers interviewed in a national survey by the Food Marketing Institute, named ‘bacteria or germs’ as a serious health risk to their food, ranking it as their number one concern.” The produce industry and the U.S. Food and Drug Administration continue to work hard to establish safe procedures for every step between the farm and the market.
Dr. Linda Harris, a food safety specialist, and Dr. Christine Bruhn, a consumer food marketing dpecialist, also affiliated with the Postharvest Technology Center, offer the following concise steps for the safe handling of produce:
- In the grocery cart and at home, keep fruits and vegetables separated from raw meat, poultry, and seafood to prevent cross-contamination.
- Once at home, store all fresh-cut ready-to-eat prepared produce in the refrigerator to keep it cold.
- Wash all whole fruits and vegetables, including larger items like melons, just before preparation for eating. Cut out damaged (bruised, discolored) areas before eating.
- Before and after handling fruits and vegetables, make sure that your work area and utensils are clean and that your hands have been washed with hot soapy water.
- Fruits and vegetables should be washed under running water. Soaking them in water increases the opportunity for cross-contamination and is not recommended.
- Produce such as apples, cucumbers and melons that can be rubbed without damage should be scrubbed using clean hands or a clean scrub brush.
- Dry washed fruits and vegetables with clean disposable paper towels.
- It is not necessary to wash ready-to-eat prewashed and packaged fresh-cut produce. If you choose to rewash this type of produce, follow the instructions above. Always wash unpackaged prepared salad mixes under running water prior to consumption.
- Once cut or prepared, all fruits and vegetables should be refrigerated promptly. After serving, refrigerate leftovers within 2 hours.
Additional produce safety resources:
"How to Properly Wash your Produce" video by Dr. Christine Bruhn.
For more University of California information about the safe handling of fruits and vegetables:
UC Home Gardening, Preservation and Storage Publications
Safe Handling of Fruits and Vegetables (pdf)
Food safety brochure (pdf)
Research helps ensure safety of leafy greens
Four years ago, a multi-state outbreak of E. coli O157:H7 in fresh baby spinach gripped the nation. Nearly 200 people in 26 states came down with the disease. Two elderly women and a 2-year-old boy died.
The outbreak was also devastating for the industry. The contaminated spinach was traced back to Central California, where growers produce 80 percent of the nation’s leafy greens. Scientists, farmers and regulators worked together to restore public confidence in products that are widely considered part of a healthy diet. Regulators and farmers created the California Leafy Green Marketing Agreement to establish a culture of food safety on leafy greens farms and researchers worked to close gaps in the body of scientific knowledge about the sources of E. coli O157:H7 in the region.
In 2006, UC and USDA researchers were already designing a four-year study of the possible sources of E. coli O157:H7 near Central California fresh produce fields when the high-profile spinach outbreak occurred. This month, data collection from rangeland and farmland, steams and irrigation canals comes to a close. The team of scientists is now analyzing the data to reach conclusions that will help prevent future food contamination.
Preliminary results reflect a diversity of E. coli O157:H7 carriers near Central Coast farms, according to Edward (Rob) Atwill, a UC Davis School of Veterinary Medicine specialist in waterborne infectious diseases and co-principal investigator of the study. Early on, free-ranging feral swine were implicated as carriers of the deadly bacteria, but it wasn’t known whether there were other sources in the environment. The researchers collected 1,233 samples of wild and feral animal scat from 38 Central Coast cattle ranches and leafy greens farms that were adjacent to riparian, annual grassland and oak woodland habitat. Eighteen of the samples were found to contain E. coli O157:H7.
The scientists found the bacteria in
- 3 of 60 brown-headed cowbirds
- 5 of 93 American crows
- 2 of 95 coyotes
- 1 of 72 deer mice
- 10 of 200 feral swine
E. coli O157:H7 was not found in scat samples from deer, opossums, raccoons, skunks, ground squirrels, or other bird and mouse species.
“Our goal over the next nine months is to finish analyzing this very large and comprehensive dataset and to identify various good agricultural practices that reduce the risk of foodborne pathogens for the produce industry,” Atwill said.
Research helps prevent contamination of fresh leafy greens.
Free information on food: Nutrition, food handling, safety, cooking, etc.
Mention that something is free and useful, and most of us will stop to take a look. And for good reason — the University of California has a number of websites that offer free information related to food.Take your time to peruse the sites listed below. There is some fascinating and very handy information to be had. Many of these sites also offer terrific publications at nominal prices, but this blog lists only those that are free . . . and we all love a bargain! Many more publications and programs are available than those listed below.
After looking at these lists, you never know when you’ll be inspired to pickle some olives or field dress a deer. As for me, my latest food craze is cheese-making. Two weeks ago I made goat cheese (chèvre, to be sure), and last weekend I made camembert and blue cheeses. Now I just have to be patient for two months while they ripen . . .
Bon appétit and healthful eating!
UC Agriculture and Natural Resources publications [link]
- Tomatoes: Safe methods to store, preserve, and enjoy [link]
- Olives: Safe methods for home pickling [link]
- Egg basics for the consumer: Packaging, storing, and nutritional information [link]
- Guidelines for food safety during short-term power outages: Consumer fact sheet [link]
- Key points of control and management for microbial food safety: Edible landscape [link]
- Safe handling of fruits and vegetables [link]
- Safe methods of canning vegetables [link]
- The healthy brown bag: 15 lunches for school-aged children [link]
Postharvest Technology Research and Information Center [link]
- Storing fresh fruits and vegetables at home – poster (first copy free) [link]
Fruit and Nut Research and Information Center [link]
- The Backyard Orchard – A plethora of publications on growing and harvesting in the home orchard [link]
Nutrition publications from UC Davis [link]
- Nutrition and health information sheets on everything from energy drinks to osteoporosis to anemia, and more [link]
- EatFit - An interactive web program to aid middle-school students in personal dietary analysis and "guided goal setting" [link]
- “Nutrition Perspectives” newsletter - Research-based information on ongoing nutrition and food-related programs [link]
- “Nutrition to Grow On” - A curriculum for grades four through six that offers teachers a direct link between the garden and nutrition education [link]
Food Safety Videos
- Take a look at these humorous — but serious — music videos on food safety by renowned food safety expert Dr. Carl Winter. Who knew that the Beatles’ classic “I Wanna Hold Your Hand” could morph into “You’d Better Wash Your Hands”? [link]
- More food safety music [link]
Cooperative Extension Offices [link]
- Many county offices have publications on food production that is specific to climatic or regional needs of that county.
Publication of the Day!
- Protecting food safety when shooting, field dressing, bringing a deer home, and cutting the carcass [link]
Center for Produce Safety awards $2.8 million
The Center for Produce Safety at UC Davis announced 17 awards to researchers around the country for projects designed to mitigate food safety risks associated with growing and harvesting fresh produce, according to a press release issued by the organization.
CPS executive director Bonnie Fernandez-Fenaroli announced the awards yesterday at the Florida Fruit & Vegetable Association’s annual convention in Naples, Fla. News of the $2.8 million disbursement was picked up by The Packer.
Six of the 17 projects are led by UC scientists. They are:
- Amphibians and reptiles as potential reservoirs of foodborne pathogens and risk reduction to protect fresh produce. Michele Jay-Russell, UC Davis. $142,523
- E. coli survival on contaminated crop residue. Steven Koike, UC Cooperative Extension. $118,000
- Pre-harvest environment influence on salmonella and its impact on increased survival capability. Linda Harris, UC Davis. $96,935
- Developing buffer zone distances between sheep grazing operations and vegetable crops to maximize food safety risks. Bruce Hoar, UC Davis. $83,000
- Risk assessment of salmonella preharvest internalization due to irrigation water quality standards for melons and cucurbits. Trevor Suslow, UC Davis. $48,747
- Imaging to evaluate potential infusion of pathogens during vacuum cooling of lettuce leaves and real-time dynamics of microbes on leaf tissues as a function of moisture content. Nitin Nitin, UC Davis. $45,008
CPS was established at UC Davis by a public and private partnership. It funds original research, maintains an online database of global produce safety research and is developing industry training and outreach programs.
"We are pleased with both the quality and the scope of the selected projects," said Bob Whitiker, chair of the CPS technical committee. "These projects go to the heart of the critical food safety questions faced daily by growers and processors in our industry, and will provide them with real-world risk management tools."
Research funding aims to minimize the risk of produce contamination.