Composition of the Protein Ingredients from Insoluble Oat Byproducts Treated with Food-Grade Enzymes, Such as Amylase, Cellulose/Xylanase, and Protease

Abstract

The manufacture of plant-based drinks has the drawback of a huge production of underexploited press cakes. In particular, the oat press cake is mainly used in feed formulation, whereas added-value applications in human nutrition are scarce. Considering that enzymatic treatments may be useful to improve the nutritional quality of these insoluble byproducts, this study aimed to evaluate whether the treatment with some food-grade enzymes, such as amylase, cellulase/xylanase, protease, and their combination, may be useful to achieve this goal. Proteomic and peptidomic studies showed that the enzymatic treatments improved the protein extraction yields and induced a release of low molecular weight (LMW) peptides that were demonstrated to provide a useful antioxidant activity. In the treated oat press cake proteins, the concentration of the bound phenolic compounds was decreased, with the exception of caffeic acid, which was increased, and avenanthramides, which remained unchanged. Finally, the enzymatic treatment decreased the concentration of phytic acid. All these results indicate that the enzymatic treatments may be useful to ameliorate the nutritional profile of these protein ingredients, before their inclusion in different food products.

High-Pressure Pasteurization of Oat Okara

“…Generally, plant products contain limiting amounts of protein [29]; however, the proximate composition of the oat okara in this study showed a high protein content of 52% (Table 4) which can be favorable for microbial growth. In comparison to other studies on oat okara, this was a high protein content with comparable studies reporting protein content of around 24-32% [10,11]. The fiber content in the present study (16%) was low compared to other studies on oat okara which have been reporting fiber contents around 26-35% [10,11].…”

“…In comparison to other studies on oat okara, this was a high protein content with comparable studies reporting protein content of around 24-32% [10,11]. The fiber content in the present study (16%) was low compared to other studies on oat okara which have been reporting fiber contents around 26-35% [10,11]. The difference in proximate composition can be due to differences in oat cultivars and production methods [30].…”

“…In the reference sample, the total dietary fiber consisted only of insoluble fiber. This is a conflicting result compared to a study by Aiello et al [10] where untreated oat okara had a soluble fiber fraction of 12% of the total dietary fiber. However, with increasing pressure, the soluble fiber fraction increased to 4% (200 MPa), 6% (400 MPa), and 9% (600 MPa) of the total dietary fiber (Table 5).…”

“…The oat okara has a high protein content (24-32% dry basis) and a high fiber content (26-35% dry basis) which makes it nutritionally valuable [10,11]. This by-stream has the potential to be utilized in food applications but, due to its high water content of approximately 65% [10,11], it has a short shelf life.…”