Suitability of different proso millet varieties for production of gluten-free fresh pasta

Despite the environmental and nutritional benefits of millet, very few food products are prepared from this grain, especially outside its countries of origin. The limited information on the characteristics of the various species accounts for scarce millet human consumption. In this frame, the aim of the study was to evaluate the pasta making performance of decorticated Proso millet. Among six millet varieties grown in two locations (Lamberton and Waseca, MN), four samples were selected based on amylose content (AC) and presence of high molecular weight prolamins (HMWp): Horizon Lamberton (25.09% AC; HMWp), Sunrise Lamberton (31.68% AC; HMWp), Earlybird Lamberton (7.88% AC; no HMWp) and Sunrise Waseca (34.77% AC; no HMWp). Fresh pasta formulation included: millet flour (65g/100g db), potato starch (23g/100g db), whole liquid eggs (10g/100g db), guar gum (1.5g/100g db), salt (0.5 g/100g db) and water (23-26g/100g dough, as needed to obtain sheetable dough). Commercial gluten-free (GF) and wheat (W) fresh pasta were used as controls. Pasta color and carotenoids content were assessed before and after cooking, using a chromameter and HPLC, respectively. Cooking loss and firmness were measured following AACC method 66-50.01; and in-vitro starch digestibility was evaluated by an enzymatic approach. Millet pasta yellowness (b*) and carotenoids content were higher than GF. Earlybird Lamberton pasta had the highest b* values and carotenoids content before and after cooking. With regard to pasta quality, cooking loss of millet pasta (1.64 – 2.36 %) was lower than that of GF and W (4.82% and 3.48%, respectively). Interestingly, Sunrise Waseca (high AC; no HMWp) yielded pasta with the lowest cooking loss value. Firmness was lower for millet (3.64 and 5.18 N for Earlybird and Horizon Lamberton, respectively) than GF (10.31 N), whereas W showed an intermediate value (5.95 N). Earlybird Lamberton - with the lowest AC - resulted in the softest sample; whereas, prolamins had a minor effect on pasta firmness. Concerning in-vitro starch digestibility, all millet pasta showed significant lower levels of rapidly digestible starch (RDS) than GF, yet had very similar levels to that of W, suggesting low glycemic impact. In conclusion, Proso millet is suitable for the production of fresh pasta with better quality than that of a commercial GF product. The effect of prolamins on pasta cooking behavior should be further investigated. These results will support the breeding program for the selection of the Proso millet varieties more suitable for fresh gluten free pasta production.