Beverley M. Watts

Emulsifying and foaming properties of commercial yellow pea (Pisum sativum L.) seed flours.

Commercial yellow pea seed flours prepared by a patented wet-milling process and pea protein isolate (PPI) were analyzed for emulsifying and foaming properties at pH 3.0, 5.0, and 7.0 and compared to soybean protein isolate (SPI). PPI and SPI formed emulsions with significantly smaller (p < 0.05) oil droplet sizes, 16-30 and 23-54 microm, respectively, than flours that primarily contained fiber such as Centara III and IV, or those that consisted mainly of starch: Centu-tex, Uptake 80 and Accu-gel. PPI was a better emulsifier than SPI at pH 7.0, and a better foaming agent at pH 3.0 and pH 7.0, although foaming capacity varied with sample concentration. Centu-tex and Uptake 80 have exactly the same chemical composition, but the latter has a much smaller flour particle size range, and had significantly smaller (p < 0.05) emulsion oil droplets. Incorporation of pea starch into SPI emulsions produced a synergistic effect that led to significant increases (p < 0.05) in emulsification capacity (reduced emulsion oil droplet size) when compared to SPI or starch alone. These results showed that PPI had generally significantly higher (p < 0.05) emulsion and foam forming properties than SPI, and that pea starch could be used to improve the quality of SPI-stabilized food emulsions.

Effect of tempering and end moisture content on the quality of micronized lentils

The use of micronization (infrared treatment) on grain legumes tempered with water has potential for reducing cooking times. Using Laird lentils, the effects of tempering conditions and moisture content following micronization were evaluated in terms of color, chemical properties and texture after 15 min cooking. The texture of cooked lentils softened as tempering moisture increased. This was related to increasing starch gelatinization and decreasing protein solubility during micronization. Changes in the pectic substances did not appear to influence texture. The reduction in hardness indicates that shorter cooking times are required for samples micronized under high moisture conditions. Lentil color changed slightly under these high moisture conditions as evidenced by the Hunterlab readings.

Micronization pretreatments for reducing the cooking time of lentils

For many grain and grain legume crops, a pretreatment step is often employed prior to processing to improve the quality of the final product. The pretreatment may be tempering, where a uniform specified moisture content in the grain is desired, or soaking, where moisture content is high and unevenly distributed. This study evaluated the effect of moisture contents and reagents as potential pretreatments for micronization (infrared heat treatment) of lentils, the objective being to reduce lentil cooking times. The texture of over-, under- and optimally cooked lentils was defined by sensory methods and by peak force values at 40% compression. As cooking time increased, sensory scores for hardness, chewiness and particle size decreased, as did peak force values. The peak force for optimally cooked lentils receiving no pretreatment was the control used to assess the effectiveness of a given pretreatment. The pretreatments studied were soaking of lentils, tempering of lentils to 20 or 40% moisture with water alone, and tempering to 20 or 40% moisture with solutions of various reagents: sodium salts of carbonate, bicarbonate, phosphate, tripolyphosphate and EDTA, and mixtures of citric and ascorbic acids. For tempering pretreatments, cooking time was reduced as moisture increased, but it was only at 40% moisture that added reagents were effective in reducing lentil cooking times. It was postulated that free water must be available in the cotyledon to allow reagents in the tempering water to reduce cooking time beyond that attainable with water alone. Potential reagents for tempering solutions used as successful micronization pretreatments were 2% sodium tripolyphosphate, mixtures of 1% citric and 2% ascorbic acid, and 150 ppm disodium EDTA.

Comparison of taste thresholds in selected Canadian and Peruvian populations

Taste detection thresholds for the four primary tastes were determined in comparable urban populations in Arequipa, Peru and Winnipeg, Canada. Detection thresholds for the Peruvians were 0.0010 mM for quinine sulphate (bitterness), 1.8 mM for sodium chloride (saltiness), 0.0705 mM for citric acid (sourness), and 21.7 mM for glucose (sweetness). Canadian thresholds were not significantly different for quinine sulphate (0.0013 mM), or for sodium chloride (1.3 mM), but were significantly lower for glucose (14.0 mM), and citric acid (0.0423 mM). Women were more sensitive than men to saltiness and sourness for both cultural groups. Food selection data revealed that the Peruvians had much higher exposures to lemons, lemonade and candy, and which might be related to the higher Peruvian thresholds for sour and sweet tastes.

Effects of Micronization on Protein and Rheological Properties of Spring Wheat

ABSTRACT This research investigated the effects of micronization, at different moisture levels, on the chemical and rheological properties of wheat. A set of tests designed to analyze protein fraction characteristics and rheological behaviors were conducted on samples from four wheat cultivars (AC Karma, AC Barrie, Glenlea, and Kanata). After being subjected to infrared radiation at three moisture levels (as-is, 16%, and 22%), the seeds were milled to produce straight-grade flour. The protein fractionation test revealed significant decreases (P ≤ 0.01) in both monomeric proteins (from 54% of total protein in the control to 37% in the tempered micronized sample) and soluble glutenins (9.4–2.5%). There was a strong negative correlation (r = -0.98) between the percentages of monomeric proteins and insoluble glutenins. Total extractable proteins of micronized samples tempered to 22% moisture decreased 43.5% when compared with nonmicronized control samples using size-exclusion HPLC (SE-HPLC). Micronization had...

Canadian and Peruvian gustatory response to bitterness and salt in instant potato purée

Canadian and Peruvian taste detection thresholds for quinine sulphate and sodium chloride were determined in an instant potato puree. These data were compared with thresholds in aqueous solution to determine the extent of threshold modification. Both Peruvians and Canadians had very low thresholds for quinine sulphate in the puree (5 to 9 ppm), but higher thresholds for sodium chloride in the potato mixture (217 to 223 ppm). With the puree, quinine sulphate thresholds were six to eleven times higher, and sodium chloride thresholds two to three times higher, for Peruvians and Canadians respectively, than with aqueous solutions. Women were more sensitive to saltiness than men, but bitterness thresholds did not differ significantly by sex. Hedonic scores were not correlated to panelists’ thresholds for either tastant. Factors affecting threshold determinations and implications for cross‐cultural research are discussed.