Cereal milling by-products as sources of nutrients and antioxidant phenolic compounds
Artigo de Conferência
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CereaIs are staple food crops and major sources of nutrition wor1dwide, but their processing generates a
large amount of by-products. In addition to environmental and economic aspects, cereal milling
by-products represent a significant loss of natural resources and nutrients when discarded as useless waste
[1,2]. Thus, in order to promote the upcyc1ing of these by-products as valuable raw materiaIs, this study
was carried out to provide a compositional and bioactive characterisation of wheat, maise and rye
by-products current1y produced in large quantities by the cereal grain milling industry. The cereal
by-products were studied for their proximate composition folIowing official methods of food analysis, and
organic acids, soluble sugars, fatty acids and tocopherols were analysed by different chromatographie
techniques [3]. After preparation of hydroethanolic extracts, the detected phenolic compounds were
characterised by HPLC-DAD-ESIIMSnand the antioxidant activity was evaluated through in vitro assays
for the ability to inhibit lipid peroxidation by monitoring the formation of thiobarbituric acid reactive
substances (TBARS), and to inhibit oxidative hemolysis caused by free radicals generated in the in vitro
system [3]. Regarding the compositional results, expressed in dry weight (dw), carbohydrates (56.35-78.12
g/100 g) were the major proximate constituents of the studied cereal by-products, folIowed by proteins
(11.2-30.0 g/100 g). The higher energy value (432.3 kcal/l00 g) was presented by wheat germ, which also
presented the highest citric acid content (0.86 g/100 g). Sucrose was the most abundant soluble sugar in alI
cereal by-products, reaching 10.4 g/100 g in wheat germ, 3.84 g/100 g in maise bran-germ mixture, and
approximately 2.9 g/100 g in wheat and rye bran samples. Unsaturated fatty acids predominated in alI
samples, given the high contents of linoleic (53.9- 57.1 %) and oleie (13.4-29.0%) acids. Wheat germ had
the highest leveis of tocopherols (22.8 mg/l00 g) and phenolic compounds (5.7 mg/g extract, with a high
content of apigenin-C-pentoside-C-hexoside). In turn, while the wheat bran extract was particularly
etIective in inhibiting the formation of TBARS, the rye bran extract was the on1y one capable of protecting
sheep erythrocytes from oxidative haemolysis. OveralI, these results are valid arguments to support the use
of cereal by-products as underexploited alternative sources of nutrients and bioactive phenolic compounds
with potential health benefits for consumers.
