Nav: Home

Vegetables fried with olive oil have more healthy properties than boiled ones

January 20, 2016

Researchers from the University of Granada (UGR) have proven that frying in Extra Virgin Olive Oil (EVOO) is the cooking method that increases the phenolic fraction present in raw vegetables used in Mediterranean diet (potato, pumpkin, tomato and eggplant) the most. This means an improvement to this foods in the cooking process.

In an article published in Food Chemistry magazine, researchers have proven that vegetables fried in EVOO improved their antioxidant capacity and the amount of phenolic compounds, which prevent chronic degenerative pathologies such as cancer, diabetes or macular degeneration.

The aim of this research was to determine the effect of applying various cooking methods on the antioxidant capacity and the amount of phenolic compounds (total and individual concentrations) present in vegetables consumed in the Mediterranean diet.

The Mediterranean diet of the Spanish population is characterized by a high intake of vegetables and EVOO. These are both an important source of dietary phenols, whose consumption has been associated with the prevention of chronic degenerative pathologies. This kind of antioxidants can be modified during the processing of the foods, increasing or decreasing their concentrations.

With this goal in mind, the researchers conceived an experiment in which they cooked 120 grams cubes of potato (Solanumtuberosum), pumpkin (Cucurbitamoschata), tomato (Licopersicumesculentum) and eggplant (Solanummelongena), all of them without seeds or skin.

Fried, boiled, or with a mix of water and EVOO

The vegetables were fried and sautéed in EVOO, boiled in water, and boiled in a mix of water and EVOO. The experiments were controlled so the processing conditions were guaranteed. The ratio between vegetable and cooking element was constant, following traditional Spanish recipes.

Processed vegetables were kept in right conditions for the measurement of moisture, fat, dry matter and total number of phenols, as well as the measurement of the antioxidant capacity, by various methods. Parallel to this, the research was completed with the determination of the content in individual phenolic compounds typical of each vegetable, using high-performance liquid chromatography (HPLC).

The results showed that using EVOO for frying vegetables increases their fat content and reduces their moisture, while this is not observed in other cooking methods.

"Comparing the content of phenols with that of raw vegetables we found increases and reductions alike, depending on the chosen method. Oil as a mean of heat transfer increases the amount of phenolic compounds in vegetables, opposite to other cooking methods such as boiling, where heat transfer is done through the water", explains one of the authors of this paper, professor Cristina Samaniego Sánchez from UGR.

EVOO transfers phenols to the vegetables

This is due to a transfer of phenols from EVOO to the vegetables, enhancing the latter with oil-exclusive phenolic compounds which are not naturally present in raw vegetables.

"Therefore, we can confirm that frying is the method that produces the greatest associated increases in the phenolic fraction, which means an improvement in the cooking process although it increases the energy density by means of the absorbed oil", says Samaniego.

All the cooking methods increased the antioxidant capacity of all four vegetables. It was a reduction of it or an absence of significant changes after boiling them in water, in certain cases.

Samaniego stresses that each cooked vegetable developed a specific profile of phenols, moisture, fat, dry matter and antioxidant activity determined by the original characteristics of the raw vegetables and the cooking method applied.

"When the phenolic content of the raw vegetable is high, the total content of phenols is increased even more if EVOO is used in the process, and boiling doesn't affect the final concentration. Therefore, we must stress that frying and sautéing conserve and enhance the phenolic composition. Hydrothermal cooking methods can be recommended when the food is consumed together with the cooking water, as the addition of EVOO improves the phenolic profile and compensates for the deficiencies of the raw food", the researcher stresses.
-end-
The results of this research are part of Jessica del Pilar Ramírez Anaya's doctoral thesis, done under the direction of UGR professors Cristina Samaniego Sánchez, Marina Villalón Mir and Herminia López-García de la Serrana, from the Department of Nutrition and Bromatology of the Faculty of Pharmacy (UGR), and also with support from the programme PROMEP/SEP, Mexico UDG-598.

University of Granada

Related Vegetables Articles:

Using enticing food labeling to make vegetables more appealing
Does labeling carrots as 'twisted citrus-glazed carrots' or green beans as 'sweet sizzilin' green beans and crispy shallots' make them more enticing and increase vegetable consumption?
Herbs, spices on vegetables may increase their appeal to men, young adults
Seasonings may entice adults -- especially men and people under age 50 -- who don't generally eat vegetables at lunchtime into increasing their vegetable intake, suggests a new study led by Joanna Manero, a graduate student in food science and human nutrition at the University of Illinois.
Eating more fruits and vegetables may lower risk of blockages in leg arteries
Eating three or more servings of fruit and vegetables per day may lower your risk of developing blockages in leg arteries.
Frozen fruits and vegetables help Americans achieve nutrition goals
New research presented today via poster presentation at the 2017 Experimental Biology meeting shows consumers who eat frozen fruits and vegetables eat more fruits and vegetables overall.
Fruits and vegetables' latest superpower? Lowering blood pressure
New study by Keck School of Medicine of USC researcher links increased dietary potassium with lower blood pressure.
Lack of fruits and vegetables increases global heart disease burden
The researchers conclude that population-based interventions to increase the consumption of fruits and vegetables could lead to millions more years of healthy life worldwide.
Up to 10 portions of fruit and vegetables a day may prevent 7.8 million premature deaths
A fruit and vegetable intake above five-a-day shows major benefit in reducing the chance of heart attack, stroke, cancer and early death.
Fruits and vegetables may slow ALS
New research at Columbia University's Mailman School of Public Health reveals that foods like fruits and vegetables that are high in antioxidant nutrients and carotenoids are associated with better function in amyotrophic lateral sclerosis (ALS) patients around the time of diagnosis.
Diet and diabetes risk: More (fruit and vegetables) is less
Healthy diets rich in fruit and vegetables have the potential to reduce incidence of type 2 diabetes, according to a new research article by Ambika Satija and colleagues published in PLOS Medicine.
Vegetables irrigated with treated wastewater expose consumers to drugs
A new study by a multidisciplinary team of researchers from the Hebrew University of Jerusalem and Hadassah Medical Center shows that eating vegetables and fruits grown in soils irrigated with reclaimed wastewater exposes consumers to minute quantities of carbamazepine, an anti-epileptic drug commonly detected in wastewater effluents.

Related Vegetables Reading:

On Vegetables: Modern Recipes for the Home Kitchen
by Jeremy Fox (Author), David Chang (Foreword), Rick Poon (Foreword)

Six Seasons: A New Way with Vegetables
by Joshua McFadden (Author), Martha Holmberg (Contributor)

The Vegetable Butcher: How to Select, Prep, Slice, Dice, and Masterfully Cook Vegetables from Artichokes to Zucchini
by Cara Mangini (Author)

Vegetable Literacy: Cooking and Gardening with Twelve Families from the Edible Plant Kingdom, with over 300 Deliciously Simple Recipes
by Deborah Madison (Author)

The Vegetable Gardener's Bible, 2nd Edition: Discover Ed's High-Yield W-O-R-D System for All North American Gardening Regions: Wide Rows, Organic Methods, Raised Beds, Deep Soil
by Edward C. Smith (Author)

Fermented Vegetables: Creative Recipes for Fermenting 64 Vegetables & Herbs in Krauts, Kimchis, Brined Pickles, Chutneys, Relishes & Pastes
by Christopher Shockey (Author), Kirsten K. Shockey (Author)

EatingWell Vegetables: The Essential Reference
by The Editors of EatingWell (Author)

The Essential Vegetable Cookbook: Simple and Satisfying Ways to Eat More Veggies
by Sammi Haber Brondo (Author)

Animal, Vegetable, Miracle: A Year of Food Life
by Barbara Kingsolver (Author), Camille Kingsolver (Author), Steven L. Hopp (Author)

Vegetable of the Day (Williams-Sonoma): 365 Recipes for Every Day of the Year
by Kate McMillan (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Circular
We're told if the economy is growing, and if we keep producing, that's a good thing. But at what cost? This hour, TED speakers explore circular systems that regenerate and re-use what we already have. Guests include economist Kate Raworth, environmental activist Tristram Stuart, landscape architect Kate Orff, entrepreneur David Katz, and graphic designer Jessi Arrington.
Now Playing: Science for the People

#503 Postpartum Blues (Rebroadcast)
When a woman gives birth, it seems like everyone wants to know how the baby is doing. What does it weigh? Is it breathing right? Did it cry? But it turns out that, in the United States, we're not doing to great at asking how the mom, who just pushed something the size of a pot roast out of something the size of a Cheerio, is doing. This week we talk to anthropologist Kate Clancy about her postpartum experience and how it is becoming distressingly common, and we speak with Julie Wiebe about prolapse, what it is and how it's...