# Out and Out Processed Products--Technology, Composition, Nutritional Value, and Health
## 1 Introduction  
Analysis of nutritional, chemical, and physical properties of oat grain, with emphasis on \(\beta\)-glucans, has led to its appreciation in human nutrition, mainly due to its health-promoting properties, including cholesterol-lowering, blood glucose-stabilizing, anti-cancer, and anti-inflammatory effects [1; 2; 3; 4].  
The oat (_Avena_ L.) genus is represented by 25 annual plant species, including field crops, wild species, and weeds. _Avena sativa_ is the main cultivated oat species, comprising about 90% of the world's oat production. Other cultivated oat species, with minor importance, include black oats (_Avena virgosa_) and red oats (_Avena byzantine_). At the same time, common wild oat (_Avena fatua_) is a weed of cereal crops, especially oats.  
Oat appeared in cultivation several thousand years later than wheat and barley, so it was unknown to ancient agricultural cultures. It was considered a secondary crop, as it initially accompanied the cultivation of other crops, mainly emmer wheat (_Triticum dicocum_ [PERSON]), as a segetal weed.  
Nowadays, globally, oat is grown on approximately 10 million hectares, accounting for only 1.5% of the acreage occupied by cereals. Oat grain is mainly used for animal feeds and human consumption but is also gaining importance in the pharmaceutical and beauty industries.  
Both the hulled (more widely grown) and the naked (unhulled) forms of oat are known. The naked form is characterized by the lack of glumellae in the grain. A high proportion of glumellae in the grain of the hulled form reduces its nutritional value and limits its usefulness for feeding monogastric animals (such as poultry). However, it is an excellent component of the feed for horses, cattle, and sheep.  
Oat grain is a raw material valued in cereal processing due to its nutritional and health-promoting qualities. Products of oat grain processing can be divided into three major categories, including (I) products obtained by milling: flakes (instant, mountain, ordinary), pear barley, bran, flour, and goats; (II) products with the addition of oat grain or substances derived from oat grain: confectionery, special breads (wheat-oat bread, fine bakery products), cereal/fruit mixes (muesli), oat preparations; and (III) products derived from oat grain (e.g., \(\beta\)-glucan) used in pharmacology, cosmetics, brewing, and chemical industries [5; 6; 7; 8].  
Oat grains, apart from highly valuable nutritional compounds, contain substances with anti-nutritional and toxic effects, i.e., saponins (avenacosides), which can irreversibly connect to the cell membrane, thus increasing its permeability [9]. Phytic acid present in oat grain may also have a negative health impact, as it has, among others, the ability to block the bioavailability of some micronutrients, such as iron, copper, zinc, or magnesium [10]. Additionally, due to the high fiber content of oat products, their digestion may lead to flatulence, bloating, and diarrhea [11].  
The present article provides an overview of the composition of oat grains and various oat products and systematizes existing knowledge about various possibilities for utilizing health-promoting properties of oat grain ingredients or oat products.