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The shelf-life of plain oatcakes and oatcakes containing a natural antioxidant (rosemary extract) was studied for 28 weeks. The biscuits were evaluated using several chemical analyses to determine oxidation (headspace analysis, free fatty acids profile, peroxide value and anisidine value), in addition to sensory testing. A selection of volatiles, including hexanal, were found to be positively correlated to three sensory parameters (aroma, flavour and aftertaste). These volatiles, responsible for the perception of off-flavour in oat biscuits, were predominantly secondary lipid breakdown products, primarily from the unsaturated fatty acids C18:1 and C18:2. The peroxide value was also found to be a useful tool to assess oxidation in oatcakes. The impact of the antioxidant was insufficient at the concentration tested to be used as a solution to prevent the development of off-flavour; however the antioxidant did appear to slow down the rancidity process., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered., (Copyright © 2012 Elsevier Ltd. All rights reserved.)