Considerations for Nut Processing

Armed with health claims and consumer affinity, nuts of all types bring cachet to foodservice products ... but not without handling and formulating considerations.

By Kantha Shelke, Ingredients Editor

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Nearly a year later, walnuts got their own, though greatly watered-down, claim: "Supportive but not conclusive research shows that eating 1.5 ounces per day of walnuts, as part of a low saturated fat and low cholesterol diet and not resulting in increased caloric intake, may reduce the risk of coronary heart disease."

The claims are slowly paying off. "More food companies than ever are now trying to enhance the nutritional profile of their products with the addition of almonds," says Harbinder Mann, technical director of the Almond Board pf California.

Mann reports that more recent clinical research developed subsequent to securing the FDA claim supports the role of almonds as a food that can lower cholesterol. Mann indicated flavonoids and vitamin E are thought to be responsible for the cholesterol-lowering abilities. Research at Tufts University suggests synergism from the flavonoids found primarily in almond skins with vitamin E in the almond meat in preventing LDL cholesterol from being oxidized. Oxidization apparently makes "bad" cholesterol stickier and more likely to clog arteries.

Extended contact with moist ingredients and freezing can soften the texture of nuts, so care must be taken in formulating for these conditions.
Extended contact with moist ingredients and freezing can soften the texture of nuts, so care must be taken in formulating for these conditions.

Not surprisingly, the almond industry is doing its part to raise awareness of the importance of flavonoids in almond skins and promote their application in foods. Almond bran powder is expected soon as a new offering for enhancing the fiber content, nutritional profile and flavor of foodservice fare.

Already armed with two health claims, walnut producers received a boost when fast food icon McDonald's created the Fruit and Walnut Salad. McDonald's version of the popular Waldorf salad includes a side of low-fat vanilla yogurt instead of mayonnaise and relies on the protein, fat and fiber content of walnuts and the fiber in apples to create the feeling of satiety.

In the process, McDonald's is mainstreaming omega-3s in restaurant foods with its selection of walnuts - which have the highest concentration of the fatty acids of all nuts. Omega-3s are unsaturated and also very susceptible to spoilage. To protect this ingredient from spoilage, McDonald's selected candied walnuts from for Diamond Foods Inc., Stockton, Calif. The candy coating adds sweetness to soften the sometimes sharper taste of walnuts and, most importantly, acts as a barrier to oxidation and spoilage.

Walnuts are showing up in the baked goods produced by quick-service restaurants with artisan bread selections. Companies such as fast-growing Panera Bread, St. Louis, and the Chicago-based Corner Bakery chain are adding walnuts to their fare. Dick Wolf, vice president of ingredients and foodservice at Diamond, also foresees walnut-based pesto and other sauces, walnut veggie burgers and nut coatings for frozen fish.

Dealing with rancidity

Note to Plant Ops -- Storage Tips

Overall, it is best to follow the "first in, first out" rule with nuts. Here are a number of considerations for their storage:

  • Buy shelled nuts only as needed and only enough so you don't have to store them and run the risk of spoilage.
  • Nuts have a tendency to absorb moisture, which can trigger a number of spoilage reactions very quickly.
  • If you must store them, ensure your inventory of nuts is refrigerated or stored in the coolest, driest place (less than 10°C and less than 65 percent relative humidity) in your facility.
  • Be particularly careful with walnuts and pecans. These have high oil content and are more prone to rancidity especially if stored in too-warm conditions.
  • All nuts contain unsaturated fats and are like magnets for any kind of odor. It is therefore, important to store all nuts in sealed containers and away from strong odors.
  • Sealing under nitrogen or vacuum packing are some of the best ways to protect nuts from insects and pests and from the damage of oxygen exposure.

Rancidity is a major issue with nuts. Tate & Lyle, Decatur, Ill., developed a panning coating process, used much like candy or confection panning, which can adhere flavors to soy nuts, hazelnuts and peanuts. The nuts are tumbled with a bland syrup for better adherence of the flavors or spice mix added next. It also gives the nuts a crisp cracker-like coating.

"The coating may be baked or fried for further color and taste development without changing the integrity of the coated nuts," says Doris Dougherty, senior food scientist at Tate & Lyle. These ingredients are finding their way into upscale restaurants where chefs are increasingly applying a nut-based crust to rapidly brown and add flavor and texture to a fish fillet, a slice of foie gras or a piece of meat.

Chefs have figured out the nutty crust also helps to seal in the juices and introduce a crunchy texture without overcooking the interior. Mark Dorian, chef at Di Pescara, a Lettuce Entertain You restaurant in Northbrook, Ill., uses almonds seasoned with herbs to coat whitefish fillets.

Shelled pecans have healthfully high quantities of unsaturated fatty acids, which, however, tend to undergo degradation resulting in rancid off-flavor. Storage at low or freezing temperatures is one way to slow spoilage but is costly.

Researchers at USDA have developed edible coatings to extend the shelf life - and prevent rancidity - of pecans at room temperature. The researchers found coating pecans with hydroxypropyl cellulose (HPC) and carboxy methylcellulose (CMC) plus various other additives restricted oxygen contact with the nut fats and prevented spoilage without affecting the texture of the nut pieces.

Low-calorie options

Fisher Nuts has promoted nuts in nontraditional food usage occasions, including as a crunchy protein source in salads.
Fisher Nuts has promoted nuts in nontraditional food usage occasions, including as a crunchy protein source in salads.

All the positive health attributes aside, nuts still have a problem with fats. In regular nuts, fat may represent as much as 50 to 70 percent of the total weight and provide an even greater proportion of the total calories.

Defatted nuts are one solution. However, they often are not as flavorful and lack the mouthfeel and textural attributes of their original, higher fat versions. This is because the process of removing fat also removes flavor compounds and often changes the texture of the material for the worse.

There are a number of methods for producing partially defatted nuts today. So formulators should inquire about the defatting method to ensure they are getting the appropriate functionality in their ingredient of choice.

Some "partially defatted peanuts" or "low-calorie peanuts," for example, are produced by pressing the raw or blanched nuts until a portion of their oil is removed. They then are steamed or cooked in water or in water containing a flavoring agent to reconstitute the pressed nuts substantially back to their original size and shape. These reconstituted nuts may then be further processed - for example, they may be heated in oil, dry roasted, etc. Often, flavoring is added to the oil or water bath step; the flavoring sometimes is of a different nut type to provide a synergistic richness in taste.

Cost notwithstanding, nuts offer food processors a valuable ability to differentiate products using subtle enhancements. In addition to conveying value and cache, nuts also offer a unique food-based rather than a nutrient-based approach for enhancing foodservice fare.

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