In its patent application, General Mills said its method relied on a cold extrusion process of pasta dough made with a balanced blend of flours and gums.
This formulation and process enabled the successful manufacture of a variety of free-from, fresh pastas including ravioli, tortellini and agnolotti; products it said were troublesome to make without gluten.
Replacing the physical role of gluten in any foodstuff was a “difficult task”, General Mills said, but it was even more difficult with pasta in which gluten is vital to the texture, structure and stretch of the final product.
It proved even tougher again, it said, when manufacturing fresh pasta products and variants with a meat or vegetable filling.
“This is because filled pasta cannot be made in a dry form, as the higher water-activity of the filling will tend to degrade the product overall. The manufacturing process requires the pasta to stretch around the filling, which requires that the pasta itself is not susceptible to tearing or breaking,” it wrote in its patent filing.
“…Accordingly, it is an object of the invention to provide a commercially manufacturable gluten-free or reduced-gluten pasta that ameliorates at least some of the problems associated with the prior art.”
Xanthan gum, egg and potato starch
General Mills said gluten-free or reduced-gluten flour formulations could be made with either grain flours that had gluten content removed or lowered, or with blends of protein-free, low-protein grain or vegetable starches and gum.
For this patent, it said a blend of rice flour and cornstarch had been chosen for a bland flavor profile, alongside a xanthan gum inclusion of 2-3% for structure and flexibility.
“Preferably, the pasta further incorporates other advantageous carbohydrate ingredients, including: rice flour; potato starch and/or tapioca starch. A particularly desirably result is achieved with the incorporation of at least 10% by mass of fresh egg,” it wrote.
The potato starch used was a modified, pre-gelatinized variant with a smaller particle size than the typical ingredient. This potato starch, in combination with the egg and xanthan gum, gave the dough structure – ensuring it was less susceptible to tearing or cracking during the filling stage – as well as ‘bite’ to the final product, required to meet sensory expectations.
Cold extrusion stretching
But General Mills said beyond formulation, its cold extrusion process was vital to successful manufacturing of fresh, filled gluten-free and reduced-gluten variants.
The steps were relatively simple – mixing all raw materials; cold extruding the mixture into sheets of around 1-1.2mm thickness; adding the filling; and shaping the pasta around it prior to cooling and packing.
General Mills said cold extrusion had to happen at temperatures of 34°C or less; pilot trials showed 32°C was optimal for plain pasta and 25.7°C for filled pasta.
“At significantly higher extrusion temperatures the starch in the pasta dough tends to begin gelatinizing. This is undesirable as it can cause the dough to ‘stick’ to the extruder screw.”
In all cases, the extruder pressure had to be 75 Bar or more: “An extrusion pressure of less than 60 Bar was trialed, however the gluten-free pasta dough product did not extrude well at this pressure. The relatively high level of moisture in the pasta dough tended to cause the dough to break apart.”
General Mills said its invention would help address the increased demand for variety in fresh, gluten-free and reduced-gluten products.
Source: WIPO Publication No. 20170273339
Published: September 28, 2017. Filed: August 3, 2015.
Title: “Pasta with reduced gluten”
Authors: General Mills – R. Vlatis