Compositional Traits of Grains and Groats of Barley, Oat and Spelt Grown at Organic and Conventional Fields

**Background:** Cereal products account for nearly half of daily caloric intake worldwide. Barley, oat, and spelt whole grains have excellent nutritional and bioactive properties, but minimally processed groats have been understudied, especially from organic systems. This study aimed to compare the compositional characteristics of harvested grains and minimally processed groats of barley, oat, and spelt grown under organic and conventional farming, and to evaluate the effects of processing and farming practices.

**Methods:** Eight cereal varieties were grown in experimental fields of the Infrastructural Centre Jablje at the Agricultural Institute of Slovenia (46°30′17.4″ N, 15°37′34.6″ E; 320 m a.s.l.) during the 2017–2018 growing season. Varieties included three winter barley varieties ('Anemone', 'BC Favorit', 'Sandra'), two spring oat varieties ('Max', 'Noni'), and three winter spelt varieties ('Ebners Rotkorn', 'Murska bela', 'Ostro'), each grown under both conventional and organic management. Harvested grains were processed: barley and oat were cleaned with a grain winnowing machine (100 kg/h capacity); spelt was threshed with a Wintersteiger LD350 and cleaned with a Haldrup DC-20 densimetric column. Pre-cleaned grains were brushed/polished using centrifugal force in a stone mill (barley 3×, oats 7×, spelt 1×). Groats yield was about 80% for barley and about 60% for oats and spelt. Compositional analysis included dry matter (103°C for 48 h), crude protein (Kjeldahl method, factor 6.25), crude fat (petroleum ether extraction), ash (550°C for 4 h), crude fibre (ISO 6865:2000), and β-glucan (enzymatic digestion, AACC 32–23.01). Total carbohydrates were calculated by difference, and caloric value using 4 kcal/g for protein and carbohydrates and 9 kcal/g for fat. Statistical analysis included LSD, correlations, and PCA.

**Key Results:** TKW ranged from 18.79 g to 56.59 g, with highest mean in barley grains (50.58 g) and lowest in oat groats (21.87 g). Protein content ranged from 9.70% to 19.81%, highest in spelt grains (mean 17.26%) and spelt groats (mean 16.85%), lowest in barley groats (mean 10.60%). Crude fibre was highest in oat grains (mean 13.18%) and lowest in barley groats (mean 1.53%). Fat content ranged from 1.37% (barley groats) to 5.24% (oat groats). Ash ranged from 1.71% (barley grains) to 3.04% (oat groats). β-glucan varied from 6.74 mg/g DW to 68.40 mg/g DW, with highest mean in oat groats (61.13 mg/g DM) and lowest in spelt grains (7.78 mg/g DM). Barley grains had mean β-glucan 48.14 mg/g DM, barley groats 51.02 mg/g DM; oat grains 37.58 mg/g DM, oat groats 61.13 mg/g DM. Field management significantly affected TKW (LSD 5% = 13.76), ash (LSD 5% = 0.43), and β-glucan (LSD 5% = 5.71) of grains, and crude fibre of groats (LSD 5% = 0.71). Caloric values ranged from 334 kcal/100 g (barley 'BC Favorit', organic) to 358 kcal/100 g (oat 'Noni', conventional). PCA showed fat, ash, TKW, and crude fibre were main factors for discriminant function 1 (45.60% of total variance), while protein and β-glucan determined function 2.

**Clinical Implications:** Minimally processed barley and oat groats are rich sources of β-glucan, a soluble dietary fibre with cholesterol-lowering and postprandial glucose-lowering effects. The EFSA recommends 4 g of β-glucans from oats or barley per 30 g of available carbohydrate per meal to reduce post-prandial glycaemic response. Regular consumption of these groats could help increase dietary β-glucan intake. Organic farming may enhance crude fibre and β-glucan content in some cereals. Spelt offers high protein content, making it a valuable alternative for protein intake. The study supports dietary guidelines recommending whole grain consumption at every meal.