Researchers from the Ohio State University report in Food Chemistry that including egg white solids in gluten-free dough formulated with hydroxypropyl methylcellulose (HPMC) produced bread with enhanced loaf volume.
Led by Rachel Crockett, the researchers note that levels of egg white solids needed to exceed 15 per cent in order to overcome potential negative interactions between the egg-derived ingredients and HPMC.
“Once egg white solids became the primary protein scaffolding in the dough (at 15% addition), it overcame negative interactions with HPMC and improved loaf volume and crumb regularity by forming an interconnected honeycomb matrix,” they wrote.
“However, this formulation may need further optimisation in ﬂavour and perceived moistness in a future study.”
Market on the rise
Gluten-free foods have rapidly increased in popularity over the past few years – partly as a result of better diagnosis of celiac disease, an autoimmune disorder triggered by exposure to gluten, the protein in wheat, barley, rye and spelt. However, there has also been a mass movement toward gluten-free products by those who have self-diagnosed wheat or gluten intolerance or who believe gluten-free to be a healthier way of eating.
Since it was valued at a modest $580m in 2004, the global market has grown at an average annual rate of 29 per cent and last year was worth $1.56bn, according to Packaged Facts. It could be worth as much as $2.6bn by 2012.
Demands for bread of consistent quality with a long shelf life have led to the use of additives in products, including emulsifiers, enzymes, reductants and antioxidants. Datem emulsifiers (diacetyl tartaric esters of mono-glycerides) are used to improve bread volume, texture and dough stability.
The Ohio State researchers tested the effects of adding soy protein isolate or egg white solids on the volume and sensory aspects of HPMC-containing gluten-free dough.
Soy protein isolate was added at 1, 2, or 3 per cent, while egg white solids were incorporated at levels of 5, 10, and 15 per cent.
Results showed a reduction in the stability of the dough at the two lower levels of egg white solids and at all levels of soy protein incorporation.
“The addition of soy protein isolate and egg white solids (5% and 10%) reduced dough stability by suppressing HPMC functionality, reducing available water, weakening HPMC interactions with the starch matrix and reducing foam stability,” they explained.
The highest level of egg white solids used was associated with improved volume.
Taste test: More work required
When the formulations were tasted by consumers, the results indicated the need for more work.
“The average of both formulations scored just below neutrality in the 9-point hedonic testing (3.7 for [2% soy protein] and 4.0 for [15% egg white solids]), indicating a ‘dislike-slightly’ score,” wrote Crockett and her co-workers.
“Both formulations exhibited ‘chemical’ aftertaste, indicating that flavour needs to be modified or masked in future formulations.
“The consumer testing, in general, suggests that more optimisation for the gluten-free formulation is required to improve consumer acceptability.”
Source: Food Chemistry
Volume 129, Issue 1, Pages 84-91
“Effects of soy protein isolate and egg white solids on the physicochemical properties of gluten-free bread “
Authors: Rachel Crockett, Pauline Ie, Yael Vodovotz