Brittany Huschka*a, Carolyn Challacombea, Jens Dreisoerner b, Koushik Seetharamana
aDepartment of Food Science, University of Guelph, Guelph, Ontario, Canada
bBrabender GmbH & Co. Duisburg, Germany
Abstract
The development of a monoacylglycerol-stabilized oil in water emulsion (MAG gel) is a recent advance in the development of alternate shortening that is free of trans fats. However, the behaviour of MAG gels in dough systems has not been investigated. In this study we investigated the effect of MAG gel at different levels (6-24%) in dough to dough with oil, interesterified shortening (IE) or a mixture of oil and monoacylglycerol in the same proportions as in the gel. Dough was prepared with different lipid types using hard or soft wheat flours at equivalent fat contents. Mixing and water absorption parameters to 500 BU were evaluated by using a Farinograph. Dough firmness, stickiness and extensibility were measured by using the texture analyzer, and gluten behavior was measured by using a Gluten Peak Tester (GPT). Water absorption values had a general decreasing trend as lipid content increased. Differences were observed in mixing behaviors in the Farinogram and the trends were similar when different lipids were used. Oil, mixture and MAG gel exhibited a delayed trend, while IE showed an opposite trend, with a quick development and increased breakdown. The MAG gel exhibited unique differences in dough rheology parameters, behaving similar to IE for stickiness, and similar to the mixture for extensibility and resistance to extension parameters. However the trends were not similar when used with hard or soft wheat dough. Depending on the type of lipid used, the maximum torque and onset of development of torque was different for the different treatments in the GPT. The trends were different between different types of lipids and whether they were used with hard or soft wheat flours. These results suggest that further evaluations are necessary to effectively use MAG gels in baked product systems. Furthermore, the GPT provided another dimension of information that was not elucidated by the traditional Farinograph or dough rheology techniques.
Introduction
A novel, structured oil was recently developed at the University of Guelph, to be utilized as a shortening alternative that is trans fat free and low in saturated fats. This material is a cellular-solid structure as an oil-in-water emulsion with water-swollen MAG multilamellae surrounding 1-5 micrometer oil globules. The globules are in contact with each other via hydrogen bonding. Questions remain on the MAG gels use and functionality in baked products, including how the structure of the MAG gel interacts with the dough matrix compared to the individual structural components and how the water in the structured MAG gel influences dough processing. These experiments attempt to compare the effects of the MAG gel on hard and soft wheat dough properties including farinogram mixing behaviour, stickiness, resistance to extension and gluten peak tester profiles compared to the unstructured components of the gel and other traditional lipid sources utilized for baked goods.
Materials and Methods
The experiments were run with hard wheat flour (HWF)(12 ±0.5% moisture, 12 ± 0.14% protein) or soft wheat flour (SWF)(12 ±0.6% moisture, 8 ± 0.03% protein). The MAG gel composition is 55.2% canola oil, 40% water, 4.5% distilled monoglyceride (Danisco, HSKA) and 0.3% stearic acid. The MAG gel was produced by vigorously mixing a hot oil-monoglyceride solution with alkaline deionized water. The additional lipids used included an unstructured mixture of the components of the MAG gel (canola oil, 7.5% distilled monoglyceride), oil and an interesterified soy shortening (ADM). The fats were added to flour on a lipid weight basis at 6, 12, 18, or 24% for the farinograph and dough rheology experiments, and at 6 or 12% for the Gluten Peak Tester.
Photograph of MAG gel
Farinograph
Hard and soft wheat flour samples with lipid levels at 0, 6, 12, 18 or 24% were analyzed in the Farinograph-E (AACC Method 54-21A), with the 50g mixing bowl. Water absorption values were adjusted to obtain a consistency of 500 BU.
Texture Analysis
Textural characteristics of the dough were measured using a TA-XTPlus Texture Analyser (Scarsdale, New York, USA). Doughs were prepared in the Farinograph-E using the method as previously stated, but were removed from the Farinograph-E 30 seconds after peak. The dough was then used for stickiness and extensibility tests. Dough stickiness was determined using the SMS/Chen-Hoseney Dough Stickiness Rig (A/DSC), and the method described by Chen and Hoseney, 1995. Resistance to extension was determined using Kieffer Dough & Gluten Extensibility Rig (A/KIE) according to the method described by Smewing, 1995.
Gluten Peak Tester
Hard wheat flour, and soft wheat flour with the addition of 6 or 12% lipid levels were analyzed with in a Gluten Peak Tester (GPT). Hard wheat flour samples were evaluated at a ratio of 0.85 (flour: water) and soft wheat flour samples were evaluated at a ratio of 1.19 (flour: water). The samples were mixed in a cup at 3000 rpm and the lift off time, peak time and peak torques was recorded.
Results
Figure 2: Farinogram curves of HWF and 6 or 24% MAG gel or mixture. MAG gel and mixture show delayed development at the 24% lipid addition level. The arrows indicate 30 seconds after peak where samples were taken for rheology testing
Figure 3: Farinogram curves of SWF and 6 or 24% MAG gel or mixture. MAG gel and mixture show delayed development at the 24% lipid addition level. The MAG gel’s slope to development is more exaggerated and occurs 5.6 minutes earlier then the mixture.
Figure 4: Water absorption to reach the 500 BU line on the Farinograph-E. Solid red line represents compensated water absorption if the water structuring the MAG gel is included in the water absorption value. The trend and amount of change was different for HWF and SWF with the MAG gel or mixture because of the functionality of their water and lipid components and the interactions with gluten and starch.
Figure 5: Stickiness values determined by Texture Analysis for HWF or SWF and 0, 6, 12, 18 or 24% lipid addition. Stickiness is lower then control in both flours with a larger decrease in SWF compared to HWF. The overall trends of stickiness is lower with the MAG gel compared to the mixture, which demonstrates an interaction between structure and protein quality.
Figure 6: Resistance to extension values determined by Texture Analysis for HWF or SWF and 0, 6, 12, 18 or 24% lipid addition. SWF values are similar to control until 18 and 24% lipid addition. Resistance to extension parameters mimic dough development times in HWF. MAG gel and mixture have similar resistance to extension parameters except when their development times differ at 18% addition in HWF.
Figure 7: . Gluten Peak Tester values for the time in which the flour lipid mixtures reach maximum gluten development, referred to as peak max time (PMT). The PMT values for the MAG gel and mixture do not follow the same trend as lipid content increases, because of the difference in the functionality of their components and the flour differences in protein quality and quantity.
Conclusions
The functionality of the water, oil and monoglyceride components in the MAG gel is not similar to the same components when added individually in an unstructured format. There are significantly different interactions between the MAG gel and HWF and SWF likely because of the interactions of their protein components and starch. Further research is necessary to identify why the structured MAG gel behaves differently than its individual components, and how gluten and/or starch contribute to the variations observed in these behaviours.
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