Textural assessment of tablespreads with emphasis on canola based products
Vane, Beverley Kaye.
Products evaluated were butter and brand name margarines made from canola, corn, soy, and sunflower oils. Corresponding brick and tub market forms of each margarine, plus an additional canola brick were included. During the latter part of the study, storage stability of canola products was tested by comparing stored and fresh products. Measurements of firmness and work to soften, obtained using trained sensory panels and the General Foods texturometer, and sensory assessments of spreadability, rate of mouthmelt and graininess were made at 4oC and 21oC. Texutural qualities were related to fatty acid composition and to melting properties defined by solid fat indices (SFI) and differential scanning calorimetry (DSC). Canola products ahd levels of less that 5% cis-cis, 9-12 octadecadienoic acid (cis-cis C18:2) and the highest levels of trans fatty acids, greater than 40% in brick products. Corn and sunflower products of both market forms had levels of cis-cis C18:2 exceeding 25%. Textural analysis showed that brick products, all of which contained greater than 40% trans plus saturated fatty acids, were significantly firmer, more difficult to work soften, less spreadable and were more slowly melting than the tub products. The larger proportion of the high melting traction in brick products provided higher SFI values at 10oC and was reflected as a lower percentage of melt at temperatures below 4oC, as seen on DSC thermograms, compared to the tub products. Canola products, the brick market form more specifically, and the sunflower products were significantly more likely to have graininess observed in them than products from the other oil sources. Tests of the effect of storage on graininess and subsequently on the textual properties were inconclusive. Products with SFI values of less than 17 were considered to be ideally spreadable by the panel; DSC melt information indicated that products which had undergone over 70% of total melt were spreadable. Sensory assessments of spreadability correlated highly (r2 = 0.94) with texturometer measures of firmness. The combination of sensory rate of mouthmelt data with textuorometer firmness assessments added 3% to the prediction of spreadability.