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Browsing by Subject "Oats (Avena sativa L.)"

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  • Saponiinit suomalaisessa kaurassa ja prosessoinnin vaikutus niiden pitoisuuksiin 
    Fedotov, Anna (2021)
    The popularity of oats (Avena sativa L.) as a food grain and their use in plant-based foods has increased in recent years due to, among other things, the proven positive health effects of oat components. Oat saponins are bioactive compounds that can potentially affect health (both positively and negatively), as well as technological properties and taste of oats and oat products. The main saponins of oat grain are avenacosides A and B. The aim of this study was to investigate the variation of avenacoside concentrations in oats grown in Finland. The samples were 20 batches of laboratory-scale dehulled, unheated oat grains (groats, G samples). In addition, the effect of processing on avenacoside concentrations was investigated for the same 20 grain batches. Oat processing included a milling process, including heat treatment, flaking, and grinding (NFL samples), and bread making (LP samples). In addition, the effect of storage (6 months at room temperature) of NFL samples on avenacosides concentrations was studied. Avenacosides were extracted from the samples with methanol-water solvent overnight at room temperature and determined by high performance liquid chromatography. The results of the study showed that the mean avenacoside concentrations in the G samples ranged from 371 to 721 µg/g dry matter. Concentrations among G samples were statistically significantly different (p<0.05). The differences may be due to genetic factors and oat growth conditions. As a result of processing, avenacoside concentrations decreased in the following order: G> NFL> LP. The milling process reduced avenacoside concentrations by an average of 26% (G vs. NFL). Bread saponin concentrations were on average 49% lower than those in oat flake flour (LP vs. NFL). Overall, concentrations decreased by an average of 62% (G vs. LP). Presumably, saponin concentrations could have been affected e.g. by heating and β-glucosidase enzyme (endogenous in NFL and produced by yeast in LP). The storage experiment showed that avenacosides were stable in NFLs during six months of storage. Data obtained can be used in other oat saponin studies and in the development of oat products. The study provided important information about the effects of oat processing on avenacoside concentrations and can be continued by analysing avenacosides levels under different baking conditions and taking samples at different production stages. The effect of storage on avenacosides under different conditions could be also studied.
  • Variation in dietary fibre content, starch quality and pasting properties of oat flours : understanding the effect of oat milling process 
    Jokinen, Iina (2020)
    Oats (Avena sativa L.) are increasing their popularity as a food ingredient since they have excellent nutritional value and great applicability in various food categories. Oats have been mainly used as feed and their food processing properties have not been studied as extensively as of the other cereal grains. Previous studies indicate that oat milling process can cause changes in the carbohydrate quality and properties of raw material. The aim of this Master’s thesis was to understand the impact of oat milling process and dry fractionation on oat ingredient characteristics in 10 samples representing Finnish oat varieties. The selected oat ingredients were non-heated oat groats, oat flour produced by industrial scale milling process and starch-rich fraction obtained from the oat flour by air classification aiming at bran-endosperm separation. The hypothesis was that the oat milling process as well as fractionation affect the physicochemical properties of oat ingredients and that the different oat raw materials may differ regarding their carbohydrate properties and processing behaviour. Dietary fibre, damaged starch and amylose contents of the oat ingredients were analysed. To understand the physicochemical properties of different oat ingredients, the pasting properties were measured with Rapid Visco Analyser (RVA). As expected, oat milling affected both quality and physicochemical properties of the oat raw materials. Milling caused a significant increase in the damaged starch content and caused changes in almost all pasting parameters. Furthermore, sample-dependent behaviour was observed in pasting properties. The oat samples showed differing behaviour during dry fractionation. The pasting properties of the air classified starch-rich fractions were different from the raw material oat flour. These results confirm that different oat raw materials exhibit different behaviour during oat milling process and that the milling process has a significant impact on physicochemical characteristics of oats.

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