Effects of laccase and transglutaminase on the physicochemical and functional properties of hybrid lupin and whey protein powder

Plant-based protein is considered a sustainable protein source and has increased in demand recently. However, products containing plant-based proteins require further modification to achieve the desired functionalities akin to those present in animal protein products. This study aimed to investigate the effects of enzymes as cross-linking reagents on the physicochemical and functional properties of hybrid plant- and animal-based proteins in which lupin and whey proteins were chosen as representatives, respectively. They were hybridised through enzymatic cross-linking using two laccases (laccase R, derived from Rhus vernicifera and laccase T, derived from Trametes versicolor) and transglutaminase (TG). The cross-linking experiments were conducted by mixing aqueous solutions of lupin flour and whey protein concentrate powder in a ratio of 1:1 of protein content under the conditions of pH 7, 40 °C for 20 h and in the presence of laccase T, laccase R, or TG. The cross-linked mixtures were freeze-dried, and the powders obtained were assessed for their cross-linking pattern, colour, charge distribution (ζ-potential), particle size, thermal stability, morphology, solubility, foaming and emulsifying properties, and total amino acid content. The findings showed that cross-linking with laccase R significantly improved the protein solubility, emulsion stability and foaming ability of the mixture, whereas these functionalities were lower in the TG-treated mixture due to extensive cross-linking. Furthermore, the mixture treated with laccase T turned brownish in colour and showed a decrease in total amino acid content which could be due to the enzyme’s oxidative cross-linking mechanism. Also, the occurrence of cross-linking in the lupin and whey mixture was indicated by changes in other investigated parameters such as particle size, ζ-potential, etc., as compared to the control samples. The obtained results suggested that enzymatic cross-linking, depending on the type of enzyme used, could impact the physicochemical and functional properties of hybrid plant- and animal-based proteins, potentially influencing their applications in food

Catalyst development for dry reforming of methane and low-temperature water-gas shift reaction

Both dry reforming of methane (DRM) and low-temperature water-gas shift (LT-WGS) processes can be integrated into a fuel cell plant and are utilised for the production of hydrogen as an important energy source for fuel cells. Improvement of current catalytic systems, and identification and development of alternative catalysts for DRM and LT-WGS reactions have formed the basis of this study. In the first stage of the work, the influence of WO3 on a Pt/CeO2 catalyst was investigated for the dry reforming of methane. It was found that Pt/CeO2 catalysts loaded with WO3 at 10 mol% to 20 mol% were very stable during 20 hours of dry reforming of methane operation in comparison to a commercial Ni catalyst. However further addition of WO3 (>70%) promoted coking on the Pt/CeO2 sample, ultimately leading to catalyst deactivation. It was also desirable to develop catalysts with higher activity to reduce operating cost, thus the physicochemical properties of different materials were assessed to identify parameters important for LT-WGS activity. Copper catalysts on metal oxide support (CeO2, ZnO, TiO2, SiO2, Al2O3, ZrO2, MgO and SnO2) were screened, while characterisation showed the catalyst adsorbing H2O and CO was crucial in generating LT-WGS activity, with Cu/ZnO attaining the highest LT-WGS activity. Lanthanum (La) was known to have high affinity for H2O, hence the effects of La doping on Cu/ZnO catalysts for use in LT-WGS reaction was investigated. The findings indicated the La promoter improved activity at a loading of 2.3 wt%, above which the activity significantly decreased. A systematic investigation has also been conducted on the effects of oxygen introduction on the Cu-based and Pt-based catalysts during LT-WGS operation with particular attention on the pyrophoricity (i.e. vulnerability to oxidative sintering) of the catalysts, and the impacts on key material characteristics. The objective was to examine whether the catalysts were suitable for fuel cell applications. It was observed that the Cu-based catalysts were pyrophoric and therefore not a suitable catalyst. No pyrophoricity was observed for Pt-based catalysts. Pt/CeO2 was the only catalyst that retained its activity, displaying no loss in specific surface area or metal dispersion throughout the entire process, rendering it a suitable candidate for fuel cell systems

Catalyst development for dry reforming of methane and low-temperature water-gas shift reaction

Both dry reforming of methane (DRM) and low-temperature water-gas shift (LT-WGS) processes can be integrated into a fuel cell plant and are utilised for the production of hydrogen as an important energy source for fuel cells. Improvement of current catalytic systems, and identification and development of alternative catalysts for DRM and LT-WGS reactions have formed the basis of this study. In the first stage of the work, the influence of WO3 on a Pt/CeO2 catalyst was investigated for the dry reforming of methane. It was found that Pt/CeO2 catalysts loaded with WO3 at 10 mol% to 20 mol% were very stable during 20 hours of dry reforming of methane operation in comparison to a commercial Ni catalyst. However further addition of WO3 (>70%) promoted coking on the Pt/CeO2 sample, ultimately leading to catalyst deactivation. It was also desirable to develop catalysts with higher activity to reduce operating cost, thus the physicochemical properties of different materials were assessed to identify parameters important for LT-WGS activity. Copper catalysts on metal oxide support (CeO2, ZnO, TiO2, SiO2, Al2O3, ZrO2, MgO and SnO2) were screened, while characterisation showed the catalyst adsorbing H2O and CO was crucial in generating LT-WGS activity, with Cu/ZnO attaining the highest LT-WGS activity. Lanthanum (La) was known to have high affinity for H2O, hence the effects of La doping on Cu/ZnO catalysts for use in LT-WGS reaction was investigated. The findings indicated the La promoter improved activity at a loading of 2.3 wt%, above which the activity significantly decreased. A systematic investigation has also been conducted on the effects of oxygen introduction on the Cu-based and Pt-based catalysts during LT-WGS operation with particular attention on the pyrophoricity (i.e. vulnerability to oxidative sintering) of the catalysts, and the impacts on key material characteristics. The objective was to examine whether the catalysts were suitable for fuel cell applications. It was observed that the Cu-based catalysts were pyrophoric and therefore not a suitable catalyst. No pyrophoricity was observed for Pt-based catalysts. Pt/CeO2 was the only catalyst that retained its activity, displaying no loss in specific surface area or metal dispersion throughout the entire process, rendering it a suitable candidate for fuel cell systems

A Comprehensive Chemical and Nutritional Analysis of New Zealand Yacon Concentrate

Global interest in yacon (Smallanthus sonchifolius) is growing due to its potential as a functional food, attributable to its unique profile of bioactives and high fructooligosaccharide (FOS) content, which vary between cultivars. Our objective was to conduct a comprehensive chemical and nutritional analysis of New Zealand yacon concentrate (NZYC)—a sweet syrup derived from the roots of cultivar ‘New Zealand’, which was first grown in the 1980s. The major minerals in NZYC were potassium, phosphorus, and calcium. The FOS content ranged from 17.6 to 52.7 g/100g. Total phenolic content ranged from 565 to 785 mg gallic acid equivalents per 100 g; chlorogenic acid and caffeic acid were the major phenolic compounds. The major amino acids were L-arginine, L-glutamic acid, L-proline, L-aspartic acid, and asparagine. The major organic acids were citric, malic, quinic, and fumaric acids. Antioxidant activity ranged from 1084.14 to 3085.78 mg Trolox equivalents per 100 g depending on the assay used. The glycaemic index (GI) value was 40 ± 0.22, classifying it as a low-GI food. These results support the classification of NZYC as a nutraceutical food product for future diet therapy applications

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze− and Air−Dried New Zealand Apricots

Pulsed electric field (PEF) pretreatment has been shown to improve the quality of dried fruits in terms of antioxidant activity and bioactive compounds. In this study, apricots were pretreated with PEF at different field strengths (0.7 kV/cm; 1.2 kV/cm and 1.8 kv/cm) at a frequency of 50 Hz, and electric pulses coming in every 20 µs for 30 s, prior to freeze−drying and air−drying treatments. PEF treatments were carried out at different field strengths. The impact of different pretreatments on the quality of dried apricot was determined in terms of physical properties, antioxidant activity, total phenolic content, and metabolite profile. PEF pretreatments significantly (p p p < 0.05) decreased sugar content. Almost all amino acids (except tyrosine, alanine, and threonine) significantly increased with increasing PEF intensity. The results of this study suggest that PEF pretreatment can influence the quality of air−dried and freeze−dried apricots in terms antioxidant activity and metabolites such as amino acids, fatty acids, sugar, organic acids, and phenolic compounds. The most effective treatment for preserving the quality of dried apricots is freeze drying combined with high−intensity (1.8 kv/cm) PEF treatment

Bioactive Components and Anticancer Activities of Spray-Dried New Zealand Tamarillo Powder

Tamarillo fruit contains many phytochemicals that have beneficial therapeutic and nutritional properties. Spray-drying is widely used to preserve fruit puree in powder form. However, to obtain high-quality fruit powder, the optimisation of spray-drying conditions is necessary, as a high drying temperature can damage sensitive bioactive compounds. This study investigated the effects of spray-drying on the microstructure, polyphenolics, total flavonoids, total carotenoids, antioxidant activity, and anticancer capacity of tamarillo powder. Response surface methodology (RSM) was used to optimise the spray-drying process to produce tamarillo powder. The independent variables were inlet drying temperature (120&ndash;160 &deg;C), flow rate (1&ndash;5 g/mL), and maltodextrin concentration (0&ndash;10%). These variables influenced the microstructural attributes, bioactive components, and cytotoxicity of the spray-dried tamarillo powder. The increase in polyphenols and antioxidant activities were favoured under high-temperature spray drying conditions and a low carrier concentration. The optimised spray-drying conditions for producing tamarillo powder with high antioxidant and anticancer activities, high yield, and stable bioactive compounds were found to be at 146.8 &deg;C inlet temperature, and a flow rate of 1.76 g/mL

Characterisation of Korean rice wine (makgeolli) prepared by different processing methods

Four methods of preparing makgeolli, a traditional Korean turbid rice wine, were reported in this study. The four processing routes include single-stage simultaneous saccharification and fermentation of glutinous rice with nuruk – a Korean starter culture (1SF-N), single-stage fermentation with nuruk and yeast (1SF-YN), two-stage fermentation (2SF) and three-stage fermentation (3SF). Chemical analysis was used to determine how the different processing routes could affect the rice wine's properties in terms of alcohol content, pH, colour, mineral content, proximate composition, antioxidant activity, total phenolic content, sugar, free amino acid, and organic acid profile. Sensory analysis using polarised projective mapping (PPM) and 62 participants found that sweetness is the most desirable attribute for makgeolli among New Zealand consumers with sourness and bitterness as less desirable. The 2SF makgeolli sample had the highest concentration of glucose (8.2 mg/mL) and maltose (107 mg/mL) and in the PPM experiment was the most preferred out of the four processing methods. The 1SF-N makgeolli sample had the highest alcohol (13% ABV), crude protein (4.9%), antioxidant activity, total phenolic (621 mg GAE/L) and free amino acids content, however, it was the least overall liked makgeolli sample. Overall, the novelty of this research includes formulating a traditional Korean turbid rice wine in a Western country environment and evaluating consumer perception of makgeolli beyond the normal clientele in South Korea. From these results it is suggested that the properties of makgeolli can be manipulated via processing to suit the brewer's sensory needs that best fits the consumer market