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Protein extracts from green leaves, consisting of mainly RuBisCO, have potential applications for human consumption. However, their properties are highly influenced by the extraction process applied. This work assessed the impact of the extraction method on the solubility profile and emulsifying properties of two protein concentrates from perennial ryegrass, obtained using two different approaches. These two methods differed in the application (or absence) of a heating step (50 °C for 30 min) to improve the removal of chloroplast material. The functionality of both protein concentrates was highly influenced by the isoelectric point of the proteins. The extract containing less residual chloroplast material showed greater solubility, up to 40 % more, and superior emulsifying capacity and stability, at non-acidic pH, similar to WPI. At pH above 6, the protein extract which contained residual chloroplast material was significantly less soluble, which limited its performance as emulsifier. Therefore, the extraction process critically impacted the final product's functionality. This work demonstrated that effectively removing chloroplast material is essential to achieve targeted techno-functional properties of an ingredient and the food product in which it is used. [Display omitted] • Protein concentrates from perennial ryegrass were explored as food emulsifiers. • Extraction method impacted the functional properties of the proteins. • Heating step during protein extraction improved emulsification properties. • Interfacial properties of both concentrates were highly influenced by the pH. • Balance between extraction yield and functional properties should be considered. [ABSTRACT FROM AUTHOR]

There is an increasing demand for developing new sources of proteins, and plants are considered the preferred alternative to animal proteins. In particular, green leaves are a source of RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase). This work assessed perennial ryegrass as a source of soluble proteins using mild treatments to preserve their functional properties. Two different extraction methods were compared, differing in the presence or abscence of a heating step (at 50 °C for 30 min) aimed to improve the removal of chloroplast material. The method that included the heating step resulted in a protein concentrate with high solubility (>90% at pH 7), and higher concentration of phenolic compounds. On the other hand, avoiding the heating step resulted in a higher extraction yield, but the residual chloroplast material affected the solubility of the final powder (>60% at pH 7). The protein extracts obtained by both methods consisted mainly of RuBisCO and presented a balanced amino acid profile covering the FAO (2011) recommendations for all the essential amino acids. Therefore, perennial ryegrass showed potential to become an alternative source of proteins for food applications with good nutritional value, whose phenolic compound, chlorophyll content and solubility was strongly dependent on the extraction process. [Display omitted] • Perennial ryegrass is an alternative source of proteins for food applications. • The final extracts obtained by both methods were composed mainly by RuBisCO. • Protein extracts had a complete amino acid profile with promising nutritional value. • Heating step during protein extraction improved the removal of chloroplast material. • Balance between extraction yield and protein solubility should be carefully assessed. [ABSTRACT FROM AUTHOR]

This study is concerned with the determination of the degree of polymerisation (DP) of fructans from chicory and rye-grass ( Lolium perenne L.) using Gel Permeation Chromatography coupled to multiangle laser light scattering and refractive index detectors (GPC/MALLS) and Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry (MALDI-TOF MS). The results show that fructans isolated from ryegrass have a DP in the range 2–>100 and the commercially produced fructans derived from chicory have a DP in range 2–61. It has been demonstrated that MALDI-TOF MS is particularly effective at determining the DP of low molar mass material but is less effective for detecting the presence of high DP molecules. On the other hand GPC/MALLS is able to provide a much broader range of DP values although it is less sensitive at very low DP. It has been shown that the two techniques give complementary information thus providing a more accurate estimate of the overall DP of the fructan molecules. [ABSTRACT FROM AUTHOR]