The study, published in the Journal of the Science of Food and Agriculture, found that shortening replacement with steam-jet processed buckwheat flour up to 20 per cent by weight produced cakes as soft as the control without volume loss.
The researchers note that a number of ingredients have emerged as fat replacers, which are generally classified into carbohydrate-, lipid-, and protein-based groups. However, they stress that the challenge remains to develop ideal fat replacers for low-fat and low-calorie products in which the texture, flavour, and appearance are not compromised.
They claim that while buckwheat flour has been used previously as an alternative to wheat flour in food formulations no studies, to their knowledge, have evaluated its use as a fat replacer.
The researchers’ hypothesis was that buckwheat flour, like other carbohydrate-based fat replacers, could mimic the functions of fat in foods as it has a gelling/thickening property due to the fact that it can bind substantial amounts of water.
Buckwheat, which is generally utilized as food in the form of flour, has received much attention due to its nutritional qualities and is a valuable source of amino acids, explained the authors. They said that the content of lysine in buckwheat, which is considered a pseudo-cereal, exceeds that of cereal grains.
Furthermore, said the researchers, it is recognized that buckwheat contains a high amount of rutin, which provides anti-inflammatory, anti-hypertensive, and antioxidant activities.
The buckwheat flour employed consisted of 72 per cent carbohydrate, 9.3 per cent protein, 1.9 per cent total lipid, and 2.2 per cent ash on a dry basis, said the authors.
For the steam jet-cooking process, 500g of buckwheat flour was suspended in 4,500ml of water and the slurry was loaded into a steam jet-cooker, and subsequent to that step was drum-dried at a steam pressure of 60 psi and a drum rotation speed of 1.6 rpm.
The thermal analysis of raw and steam jet-cooked buckwheat flours was performed by using a differential scanning calorimeter (DSC) and the effect of steam jet-cooking on the water hydration properties including the water absorption index (WAI), water solubility (WS) and swelling power (SP) were calculated, based on the method of Lee and Inglett, said the authors.
The flow behaviours of steam jet-cooked buckwheat flour suspensions were evaluated and samples were covered with a thin layer of mineral oil to prevent dehydration during rheological testing, they continued.
The cake ingredients, said the researchers, were purchased from commercial sources and preparation was based on the Approved Methods of the AACC with slight modifications, while the formulation for the control cake consisted of 200 g of all-purpose flour; 100 g shortening, 220 g sugar, 250 ml water, 24 g non-fat dry milk, 6 g NaCl, 12 g baking powder, and 18 g dried egg white.
For shortening replacement, they added, the steam jet-cooked buckwheat flour was mixed with distilled water at a concentration of 20 per cent (w/w), brought to the boil, and placed at 4°C overnight to form a gel. It was then incorporated into the cake formulation by replacing shortening up to 60 per cent on an equal shortening weight basis.
Steam jet-cooking caused the integrity of buckwheat flour components to be disrupted, significantly changing the physical properties of the buckwheat flour. The process caused structural breakdown and starch gelatinization of buckwheat flour, thus increasing its water hydration properties, noted the researchers.
In addition, they found that, in the pasting measurements, steam jet-cooked buckwheat flour exhibited high initial viscosity, while no peak viscosity was observed. Also, the suspensions of steam jet-cooked buckwheat flour exhibited shear-thinning behaviors, which were well characterized by the power law model, said the authors.
And they noted that when shortening in cakes was replaced with steam jet-cooked buckwheat gels, the specific gravity of cake batters significantly increased, consequently affecting cake volume after baking.
However, the researchers determined that when only 20 per cent of shortening was substituted with steam jet-cooked buckwheat it produced low-fat cakes with comparable volume and textural properties to the control.
Source: Journal of the Science of Food and Agriculture
Published online ahead of print: DOI 10.1002/jsfa.4072
Title: Functional characterization of steam jet-cooked buckwheat flour as a fat replacer in cake-baking Authors: B Min, S Mi Lee, S-Ho Yoo, G E. Inglettb, S Lee