Nuts are generally roasted to improve their taste, aroma and
crunchy texture. Roasting is defined as cooking using dry heat,
which cooks the food evenly on all sides. Most nuts are roasted
without their shell, except for pistachios, which are often
roasted in-shell. Roasting nuts changes their structure,
chemical composition, color, and decreases their moisture
content.
There are two main kinds of roasting: Dry roasting without oil.
Nuts can be dry roasted in the oven or in a frying pan. Oil
roasting can also be done in the oven or in a frying pan.
Raw and dry-roasted nuts have very similar amounts of fat, carbs
and protein, but roasted nuts have slightly more fat and
calories per gram. During roasting, nuts lose some moisture, so
a roasted nut weighs less than a raw nut. That explains why the
fat content per ounce is slightly higher in roasted nuts. Some
studies indicate that trans fats are formed after roasting, but
the amount is negligible
One ounce (28 grams) of raw almonds contains 161 calories and 14
grams of fat. The same amount of dry-roasted almonds contains
167 calories and 15 grams of fat. Both types contain similar
amounts of calories, protein, carbs, and fiber, but roasting
nuts may damage their healthy fat, and reduce their nutrient
content.
Eating roasted or non-roasted nuts may reduce your risk of heart
disease. Nuts are filled with healthy fats and the amino acid
arginine, which relaxes constricted arteries and increases blood
flow, according to the Harvard School of Public Health. Nuts
also contain vitamin E, folic acid, fiber, and potassium. Good
nut choices include almonds, Brazil nuts, cashews, filberts,
peanuts, pistachios, and walnuts.