Towards plant-based drinks with complete and digestible proteins : Formulation, protein quality, and the effect of phytase on protein digestibility of hemp-quinoa and rapeseed-faba bean beverages

Abstract

There is a market gap regarding diversity within plant-based beverages with a complete amino acid profile. For this reason, new ingredients that could be used for the formulation of two plant-based drinks were researched: one combining raw ingredients like seeds, and the other one using protein isolates. Once the final formulations were decided, the resulted drinks included a beverage made of quinoa and hemp hearts, and another one made from rapeseed and faba bean protein isolates.
Afterwards, the drinks were analysed following the Dumas method. Its total nitrogen and protein content were evaluated, and for the hemp-quinoa drink a 1.12% of protein was obtained, while for the rapeseed-faba drink, 3.36% protein content was reached.
Following the calculation of the amino acid scores during the formulation step, the protein digestibility-corrected amino acid score (PDCAAS) and the digestible indispensable amino acid score (DIAAS) were calculated for the hemp-quinoa (87%) and the rapeseed-faba (94%) beverages, respectively. In order to find out the actual amount of all the amino acids present in each of the drinks, samples were sent to Eurofins, where a total amino acid analysis was performed. The FAO/WHO amino acid requirements for adults were used as a reference. Using these values, for the hemp-quinoa beverage the only limiting amino acid was lysine (96%), while the estimated AAS presented leucine and lysine as the limiting amino acids (97.3% and 97.2%, respectively). As for the rapeseed-faba drink, while the estimated AAS was over 100%, the actual values presented two limiting amino acids: leucine (99%) and valine (97%).
Since both drinks were of plant-based origin, the study of the presence of different antinutrients was contemplated. Phytic acid was especially considered, as it can bind to proteins hindering their absorption rates. The use of food-grade phytase was applied to reduce the phytic acid content and, subsequently, the Bradford assay was used to evaluate if it led to an increase in the solubility of the proteins, and phytic acid content was also measured. The results concluded that even though the phytic acid was reduced after phytase treatment, this did not impact the protein solubility.
An in vitro enzymatic digestion was performed following the INFOGEST protocol in both beverages before and after the phytase treatment. The resulting products were analysed using a colourimetric assay (OPA) and SDS-PAGE to evaluate the effectiveness of the digestion and of the phytase treatment. The conclusion reached was that the digestion indeed worked, as the concentration of free amino acids increased and the band intensity in the gel was lower for the digested samples, but with no significant difference between phytase-treated and untreated samples.
The conclusion reached was that there is a challenge in finding the balance between making a plant-based beverage with a complete amino acid profile while keeping it palatable by consumers. Even with the limitations involved in this thesis like time and equipment, two beverages were formulated that almost met the amino acid score goal while achieving positive flavours and mouthfeel.

Popular Abstract

Plant-based drinks with better protein: is it possible?
Yes. And we can (almost) prove it. Plant beverages can have all the essential amino acids (those our bodies cannot make on their own) in the right amounts, meaning they can be complete protein sources just like cow’s milk, when foods such as beans and seeds are combined, as they complete each other’s missing amino acids. We set out to make two drinks: hemp-quinoa team on one side, and rapeseed-faba bean isolates on the other, and the result is... that they are extremely close to being complete!
Both drinks have all 9 essential amino acids in almost the perfect ratio for adults, and by that we mean meeting 100% of our body’s needs. By combining hemp and quinoa whole seeds, lysine is the only essential amino acid that does not fully reach the target, reaching 96% of the amount adults need. The rapeseed and faba bean isolates make a beverage that is missing a bit of leucine and valine, meeting 99% and 97% of our needs, respectively. These gaps are very small, and a few adjustments to the ingredient ratios and to the formulation could push both drinks toward becoming complete protein sources.
Still, both beverages are already far ahead of most plant milk-alternatives on the market, including oat, almond, and rice drinks. The rapeseed-faba bean drink’s nutritional profile is similar to or even better than cow’s milk. It has 3.4% protein, the same as cow’s milk, but with lower levels of saturated fats and sugar. The quinoa-hemp beverage has less protein (1.1%), but this amount is still higher than almond and rice beverages, and it also has a low fat and sugar content.
Why does any of this matter? A growing number of people are choosing plant-based diets for environmental and ethical reasons, but also for personal health benefits. Sweden’s plant-based dairy market alone is estimated at 140 million dollars. However, most plant-based milk alternatives are weak protein sources, with low protein content, incomplete amino acid profiles, and proteins that are difficult to digest. There is a real market gap for plant drinks that can actually compete with cow’s milk on protein quality and quantity.
Better protein does not only mean having all the essential amino acids in the right amounts, but it also means making sure that the protein is easy to digest, so that the amino acids are released during digestion, then absorbed, and made available for the body to use. Plant proteins are usually more difficult to digest than animal proteins for a few reasons. One of them is that they contain antinutrients, such as phytic acid, which binds to minerals and proteins and blocks them from being properly digested. For this very reason, we decided to add an extra ingredient to our formulation: phytase, the enzyme that breaks down phytic acid. By breaking down phytic acid, the proteins and minerals are freed and can be digested and absorbed. By reducing phytic acid, we aimed to make the digestion of protein easier.
But how do we know if our plan actually worked? As scientists often do, we simulated the plant-based milk-alternatives’ digestion in the lab, analysed the drinks before and after digestion with and without phytase, and then compared results. The enzymatic treatment did reduce phytic acid in both beverages before digestion in moderate amounts, however, we found no clear evidence that the proteins were digested more easily. We think that not enough phytic acid was reduced, and that it would be interesting to explore if, by accommodating the enzyme to its preferred conditions (it works best in acidic environments, but our drinks are neutral), the phytic acid could be further reduced and perhaps lead to better-digested proteins.
For our beverages, we picked unconventional ingredient combinations, hemp + quinoa and rapeseed + faba bean, that do not exist as commercial products today. We also tried to choose our ingredients based on how sustainable they are. The rapeseed protein isolate (Vertis™ CanolaPRO®) is a certified upcycled plant protein obtained from rapeseed meal, oil extraction leftovers. Faba bean crops have low carbon footprints and fix nitrogen from the air, meaning less fertilisers needs to be used, while hemp is considered a highly sustainable crop because it absorbs and stores carbon dioxide.
This work provides a starting point for researchers and food developers interested in creating better plant-based milk alternatives. It shows that combining plant sources that complete each other’s amino acid profiles is a powerful strategy for improving amino acid deficiencies and potentially reaching protein completeness, with careful considerations about the ingredients’ ratio. It also provides knowledge on treating foods with phytase as a base for future research into improving plant protein digestibility.

• author: Neri, Cassia and Gómez Gómez-Díaz, Rosalina
• supervisor: Javier Linares-Pastén; Rana Cheaib; Jeanette Lindau
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLTM02 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering; Agriculture and Food Sciences
• keywords: plant-based drinks, complete amino acid profile, hemp, quinoa, rapeseed, faba bean, protein isolates, phytase, protein digestibility, in vitro digestion simulation, INFOGEST, plant-based milk alternatives, food engineering nutrition and food chemistry
• language: English
• id: 9238192
• date added to LUP: 2026-06-16 16:05:10
• date last changed: 2026-06-16 16:05:10