Two of the most prevalent technological options for the food industry to process raw food materials into preserved or consumable products are chemical conversion or physical methods. Food technologists adapt various chemical engineering unit operations to food processing where generally no deliberate chemical reactions are involved. In contrast very few chemical reactions are in vogue in processing foods as the intention of processing is to preserve every nutrients, which are all chemicals with different molecular structure, as far as possible for delivery to the consumer. Of course there are unintentional consequences of processing, especially at temperatures above the ambient one and reactions involving amino acids, sugar, vitamins, minerals, fatty acids, etc are unavoidable. Some of these reactions are considered desirable while many others are unacceptable as far as the consumer is concerned. Maillard reaction that progressively yields brown chemical artifacts are liked in products like baked foods while undesirable color tints imparted due this very same reaction is sought to be stopped, especially in products with natural white color. Use of chemicals like preservatives, emulsifiers, stabilizers, antioxidants etc which are chemicals, some of them natural and others synthetic cannot make these foods chemically processed.
Physical processes like flour milling, grain polishing, flaking, puffing, popping, sugar recovery from cane, milk pasteurization, oil seed crushing and many others invariably depend on mechanical operations and temperature rise is very minimal. Of course there are high temperature processes like baking, coffee roasting, coco bean processing, extrusion cooking, canning, frying, cooking, grilling etc but temperatures generally do not exceed 200C. One of the unavoidable consequences of food processing or cooking is that there is a loss of nutrients like vitamins and others, thermally unstable, which varies from process to process and product to product. The fortification and enrichment technologies help the industry to make up for the nutrient losses albeit to a limited extent. Still the consumer is always skeptical about the healthiness of many products going through the industrial manufacturing hubs. Frozen foods are invariably preferred because of the perception that at sub-zero temperatures nutrients are stabilized, reducing the possibility of spoilage considerably. Besides these foods have relatively long shelf life that enables consumers to store them at home.
Fermented foods which are derived by the action of beneficial microorganisms belong to a group of products evolved historically over centuries of human civilization. Wine with a history of thousands of years are made from grapes and other high sugar fruits using yeast as the "biological converter". Same is true with regard to Beer made by fermentation from grains and hops. Products derived by fermentation of grains, fruits, molasses etc and after subsequent physical processing yield many established lines of product like Whiskey, Gin, Rum, Vodka, etc. The simplicity of yeast fermentation lends itself to house hold preparation of wines while the flourishing existence of illicit liquor making industry reflects the ease with which yeast fermented products can be made with minimum facilities. Another classical example is bread making where again yeast is involved under aerobic conditions. Then there are many other products like yogurt, cheese, Indian idli and dosa and a hundred other products made and eaten in over 70 countries of the world. One thing in common with all these products is that all of them involve use of one or more microorganisms with assured safety.
There are many processes employed by the food industry using enzyme preparations derived from microorganisms, plant and animal sources and by no stretch of imagination the end products can be called fermented foods. Conversion of starch into sugars catalyzed by amylase and amylo glucosidase enzymes or manufacture of High Fructose Corn Syrup (HFCS) through Glucose Isomerase or making Pectinase clarified fruit juices or tenderizing of meat using Papain and many such enzyme mediated processing cannot be classified as fermentation process. Similarly there is an important emerging area that has great relevance to food preservation and that is Bacteriocin class of Bio-preservatives obtained from safe bacterial species. Foods which can be preserved by these natural antibiotic substances will have to be considered as partly "Bioprocessed". Probably it would be more appropriate, when natural microorganisms and the derived enzymes from them or plant and animal based enzymes are used in preservation or conversion, if they are called Bioprocessed foods. Bioprocessing is relevant even to many non-food products also and one of the most promising areas for using this process is in the energy sector where non-food biomass is sought to be converted into readily usable energy forms like alcohol.