Fresh is still best...
Nearly every type of food preparation affects the nutrient levels in food. Common preparation steps like boiling or steaming can wash out nutrients as vitamins migrate into the cooking liquid.
The same occurs when you broil or roast veggies. Drying and reheating foods also decrease nutritional levels and so does freezing and freeze drying. Freezing and freeze drying reportedly have the least impact on nutrition, but the actual nutritional losses depend the type of food and processing temperatures. Basically, if you can't get to the store and can't get fresh then frozen or freeze dried are your next best option but fresh is still the best.
While the amount of nutrient loss caused by cooking has encouraged some to turn to raw food preparation, which is a positive step, it's important to note that cooking has benefits too. Cooking kills potentially harmful microorganisms that are present in food.
The concern of raw consumption of fruits and vegetables is easily overcome by washing thoroughly before serving but, washing may not eliminate all contamination. Recently, a number of food-borne illness outbreaks have been traced to fresh fruits and vegetables that were processed under less than sanitary conditions. These outbreaks were traced to the quality of the water used for washing and chilling produce after it was harvested.
Alfalfa sprouts and other raw sprouts pose a particular challenge because the conditions under which they are sprouted are ideal for growing microbes and because they are eaten without further cooking. This means that bacteria present on the seeds can grow to high numbers of pathogens on the sprouts. Unpasteurized fruit juice can also be contaminated if there are pathogens in or on the fruit or water used to make it.
Still, considering the small volume of food your bird actually consumes, what he/she does get ought to be the most nutritious possible. Likely this was one of the primary objectives for the development of pellets, but we all know that pellets alone don't provide the balance needed for healthy birds. We still feel the best possible diet is a well-balanced offering of fresh fruits and vegetables, grains, healthy seeds (yes they DO exist), and tree nuts. Check out our Diet Section for information on all these ingredients.
There are many factors to consider when developing your food plan so do some research on raw food nutrition. We happen to like the FaceBook group Avian Raw Whole Food Nutrition. This is a closed group dedicated to discussions on avian raw diets ... pop over and take a look.
We have also provided for you the following table so you can see the impact of processing on nutritional levels; the table is provided as a general guide only.
To learn more about food prep safety on the CDC website.