GERMINATION AS A BIO-TECHNOLOGICAL PROCESS TO ENHANCE THE USE OF QUINOA (CHENOPODIUM QUINOA WILLD.) IN CEREAL-BASED PRODUCTS

Awareness of the several agronomic, environmental, and health benefits of quinoa has led to a constant increase in its production and consumption not only in South America - where it is a native crop – but also in Europe and the United States. However, producing cereal products enriched with quinoa alters some quality characteristics, including sensory acceptance. Indeed, several anti-nutritional factors, such as saponins, are concentrated in the grain pericarp. These bitter substances may interfere with the digestion and absorption of various food components. The most common of them are washing and pearling (applied separately or in combination); both have a direct effect on saponins, either by solubilisation and/or by the mechanical removal of seed layers. More recently fermentation have been proposed as a process able to mask the bitterness with aromatic compounds and/or sugar formation. Sprouting has been proposed as a suitable process to enhance the nutritional traits of grains, including quinoa. Whereas, there is a lack of information about sprouting effects on starch and protein features and their impact on the functional properties of quinoa seeds and the related flour. Moreover, the effectiveness of sprouting on decreasing the saponin content has never been demonstrated. The present work aimed at understanding the effects of sprouting on the molecular, functional and sensory properties of quinoa, in order to enhance the use of sprouted seeds or flour as a new ingredient in food formulation, with particular interest in bread-making applications. Whole quinoa was sprouted for 12, 24, 48 and 72 h at 22 °C and 90% of relative humidity and dried at 55 °C for 6 h. The development of amylases and proteases promoted changes in starch and protein features. After 48 h sprouting, starch granules were less effective in gelatinizing during heating, and less prompted to re-associate in a more ordered structure during cooling. As regards proteins, the process mostly affected albumin and globulin fractions and, once again, the main events were observed after 48 h of sprouting. Such molecular changes affected flour functionality, by: (1) decreasing the ability of absorbing and retaining water (as shown by WAI90 and WSI indices); (2) lowering syneresis during freeze-thawing; (3) decreasing foaming capacity but improving the stability of the foam. The sensory traits of quinoa were assessed by electronic tongue. Sprouting determined an increase in sourness in agreement with the increase in total titratable acidity and the decrease in pH. Interestingly, quinoa was perceived as less bitter after 48 h of sprouting, as the consequence of the decrease in saponin amount, determined by TLC or LC-HR-MS/MS, and confirming the decrease in foaming capacity as measured by the afrosimetric method. Substitution of wheat flour with flour from sprouted quinoa showed that 20% enrichment level was associated with a good gluten aggregation and the formation of dough able to maintain its structure during leavening and retain a high percentage of gas. These dough characteristics allow bread to reach the highest specific volume and the lowest crumb firmness up to three days of storage in comparison to 10% and 30% of substitution. The behavior of sprouted quinoa enriched-bread was compared with that of pearled quinoa-enriched bread at the same percentage (20%). Results showed that sprouting can be preferred to pearling, which is the most common pre-treatment for allowing the use of quinoa in bread-making. Indeed, sprouted quinoa-enriched bread showed the best results in terms of physical (volume, softness) and sensory (decrease in bitterness) traits.