Functional properties of select edible oilseed proteins

Sensitive ELISA and lateral flow immunoassay for the detection of walnut traces in processed food and working surfaces

Walnut represents one of the most allergenic nuts that can be found as a hidden allergen. In this study, sandwich ELISA and lateral flow immunoassay (LFIA), based on the determination of Jug r 1, were developed to detect walnut. Cross-reactivity was only found with Pecan nut among a panel of 88 food ingredients tested. ELISA and LFIA could detect 0.25 and 0.5 µg/g of walnut protein in complex food matrices spiked with walnut extract, respectively. Furthermore, walnut was detected in blended (chocolate) and incurred foods (ice cream and bread) added with ground walnut at levels of 0.5 and 1.5 µg protein/g by ELISA and LFIA, respectively. LFIA could also detect 0.1 μg of walnut protein in working surfaces. ELISA displayed acceptable precision and high recovery (71-97 %) and both tests were robust. This study shows that developed ELISA and LFIA are reliable tools to be applied in allergen control programs.

Application of plant-based proteins for fortification of oat yogurt storage stability and bioactivity

The purpose of this study was to evaluate the addition of plant-based peanut protein isolate (PNP) and commercial pea protein (CPP) on the quality of oat yogurt (OY). PNP and CPP were partially characterized for techno-functional properties. PNP had higher solubility (acidic and basic regions) and emulsifying activity than CPP. The water absorption capacity of CPP is significantly (p < 0.05) higher than PNP. Amino acid profiles of PNP and CPP were promising for the nutritional enhancement of OYs. OYs with PNP or CPP (0.5, 1, 2% w/v) were stored for 21 days and compared to the control group with no protein. On the 21st day of storage, (i) PNP- or CPP-added OYs were found to be comparable to the control with respect to post-acidification and viscosity, (ii) syneresis was more evident in PNP-added OYs than in CPP-added ones, (iii) total color change of 1% CPP-added OY was equal to the control, and (iv) hardnesses of control, 2% PNP, and 2% CPP-added OYs were 0.29 ± 0.00, 0.39 ± 0.01, and 0.45 ± 0.00 N, respectively. No adverse sensory effects were detected for CPP or PNP addition. Both proteins increased the total phenolic, soluble protein, antioxidant, antihypertensive, and α-glucosidase inhibition activity of oat milk and OYs, with PNP superior to CPP overall. Compared to oat milk, the fermentation process increased ACE inhibition activity in in vitro digested samples, whereas it reduced digested yogurts' antioxidant activity. Utilization of PNP in OY can solve the waste problem of peanut producers and the texture problem of the OY producers while formulating a functional product. PRACTICAL APPLICATION: Plant-based (PB) yogurts have a growing consumer demand. The low-protein content of PB yogurts results in low acceptance with respect to their undesirable textural and sensorial attributes. This study provided a technical basis for the PB yogurt manufacturers focusing on the addition of commercial pea protein and isolated peanut protein into oat yogurt formulation without any thickeners or flavors. In vitro digestion of protein-added oat milk and oat yogurts showed the benefits of fermentation on bioactivity to the consumers.

Ultrasound-Assisted Extraction of Protein from Pumpkin Seed Press Cake: Impact on Protein Yield and Techno-Functionality

Conventional solvent-based methods widely used for isolating plant proteins may deliver an unsatisfactory protein yield and/or result in protein degradation. The present study started with the optimization of pumpkin seed protein from press cake by alkaline extraction and subsequent isoelectric precipitation. Subsequently, extraction was supported by ultrasound under three conditions: ultrasonic treatment followed by alkaline extraction (US+AE), concomitant ultrasonic treatment and alkaline extraction (UAE), and alkaline extraction followed by ultrasonic treatment (AE+US). Compared to the control group, an increase in protein yield was achieved after ultrasonic treatment, while the highest protein yield was obtained with AE+US (57.8 ± 2.0%). Isolates with a protein content of 94.04 ± 0.77 g/100 g and a yield of 43.6 ± 0.97% were obtained under optimized conditions. Following ultrasonic treatment applied during extraction, solubility, foaming capacity, foam stability, and denaturation enthalpy of the isolated protein increased, and water binding capacity decreased as compared to non-sonicated samples. The d₉₀ particle size percentile of the extracted suspensions was 376.68 ± 38.32 µm for the control experiments, and particle size was significantly reduced in ultrasound-assisted treatments down to d₉₀ = 179.93 ± 13.24 µm for the AE+US treatment). Generally, ultrasonication resulted in a significant increase in protein yield and improved techno-functional properties of the isolates.

Critical overview of biorefinery approaches for valorization of protein rich tree nut oil industry by-product

This review explores reutilization opportunities of protein-rich bio-waste derived from the major tree nuts (almonds, walnuts, and cashew nuts) oil processing industries through biorefinery strategies. The mechanically pressed out oil cakes of these nuts have high protein (45-55%), carbohydrate (30-35%), and fiber that could be utilized to produce bioactive peptides, biofuels, and dietary fiber, respectively; all of which can fetch substantially greater value than its current utilization as a cattle feed. Specific attention has been given to the production, characterization, and application of nut-based de-oiled cake hydrolysates for therapeutic benefits including antioxidant, antihypertensive and neuroprotective properties. The often-neglected safety/toxicological evaluation of the hydrolysates/peptide sequences has also been described. Based on the available data, it is concluded that enzymatic hydrolysis is a preferred method than microbial fermentation for the value addition of de-oiled tree nut cakes. Further, critical insights on the existing literature as well as potential research ideas have also been proposed.

Novel Protein Sources for Applications in Meat-Alternative Products—Insight and Challenges

Many people are increasingly interested in a vegetarian or vegan diet. Looking at the research and the available options in the market, there are two generations of products based on typical proteins, such as soy or gluten, and newer generation proteins, such as peas or faba beans, or even proteins based on previously used feed proteins. In the review, we present the characteristics of several proteins that can be consumed as alternatives to first-generation proteins used in vegan foods. In the following part of the work, we describe the research in which novel protein sources were used in terms of the product they are used for. The paper describes protein sources such as cereal proteins, oilseeds proteins coming from the cakes after oil pressing, and novel sources such as algae, insects, and fungus for use in meat analog products. Technological processes that can make non-animal proteins similar to meat are also discussed, as well as the challenges faced by technologists working in the field of vegan products.

Obtaining cashew kernel protein concentrate from nut processing by-product and its use to formulate vegetal burger

Abstract Broken kernels are among the by-products of processing cashew nuts which have less commercial value. The present work aimed to obtain a cashew kernel protein concentrate from broken kernels, and then characterize it as well as using it in a vegetable burger formulation. The concentrate was obtained by isoelectric precipitation at four different pHs and subsequent drying. Higher yield was 58.6% of proteins (pH 4.0 and 4.5). The concentrate showed Water Absorption Capacity (WAC) of 1.85 mL/g and Oil Absorption Capacity (OAC) of 1.06 mL/g, as well as low solubility in aqueous medium and low foaming capacity. The concentrate was used in vegetable burger production as a substitute for soybean protein. The burgers were submitted to sensory evaluation and obtained an average of 6.6 on a nine-point scale, thus being within the acceptance zone. Regarding the purchase intent, 60% of the judges would probably or would certainly buy the product. Therefore, the cashew kernel protein concentrate can be used as a protein ingredient for food formulation. Producing cashew kernel protein concentrate allows the use of broken kernels generated in the cashew nut industrial process.

Optimising the use of proteins from rich meat co-products and non-meat alternatives: Nutritional, technological and allergenicity challenges

An exponential growth in the global demand for high quality proteins over the next 20 years is expected, mainly due to global population growth and the increasing awareness toward protein rich foods for more nutritive diets. Coupled with this, is the pressing need for more sustainable approaches within a bio-economy mindset. Although meat production is expected to increase to address this rising demand, a better use of the currently available resources provided by the food, and specially, the meat industry is required. In this regard, despite the high-quality proteins and other nutrients found in meat co-products; they are currently underused and their valorisation needs to be revisited. Also, emerging protein sources need to be investigated to alleviate the environmental pressure coming from the meat industry. In this review, the main focus was attributed to (i) the current and forthcoming challenges for the use of meat co-products as meat replacers to produce a new range of meat derived products (with high nutritional value, improved technological properties and better consumer acceptance); (ii) their performance regarding to the non-animal origin proteins currently used as meat protein replacers; and (iii) the allergenicity of the proteins that might fall into the category of novel protein sources.

Heat induced denaturation, aggregation and gelation of almond proteins in skim and full fat almond milk

The effect of thermal treatment (45-95 °C for 30 min) on the structure of almond milk proteins was assessed, as the unfolding and association of these proteins in response to heat is not well understood. Above 55 °C, protein surface hydrophobicity and particle size increased and alpha helical structure decreased, reducing the stability of skim or full fat milk. Fractal protein clusters were observed at 65-75 °C and weakly flocculated gels with a continuous protein network occurred at 85-95 °C, resulting in gels with high water holding capacity and a strength similar to dairy gels. The presence of almond fat increased gel strength but led to a more heterogenous microstructure, which may be improved by homogenisation. Elasticity could also be increased with protein concentration. This study improves our understanding of the heat stability of almond milk proteins and indicates their potential as a gelling ingredient for vegan and vegetarian products.

Comparison of wheat, soybean, rice, and pea protein properties for effective applications in food products

Pea and rice proteins are promising to substitute allergenic proteins, and increasingly, play important roles in the food industry because of their hypoallergenic characteristics and nutritional value. However, manufacturers generally provide limited functionality information on these proteins. Therefore, this study comprehensively compared functional properties of wheat, soybean, rice, and pea proteins for their industrial applications and illustrated correlation among various functionalities. Results showed that protein solubility (PS) was highly related to its water absorption (WA) capacity, emulsifying activity index (EAI), and emulsion stability index (ESI). The overall functionality of pea protein was close to that of soybean protein while rice protein cannot match with all other proteins. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated the composition of each protein was unique. While the deconvolution of the amide I band of the Raman spectra indicated soybean and pea proteins that shared similar features, but they were different from that of wheat and rice proteins. PRACTICAL APPLICATIONS: Due to the allergenicity of wheat and soybean proteins, food manufacturers are looking for alternative protein sources. Rice and Pea proteins are promising substitutes because of their "allergen-friendly" as well as their emergence in the food market. This study provided a comprehensive comparison of the functionality of commercially available wheat, soybean, rice, and pea proteins. The information presented in this study would be helpful to food scientists, scholars, or engineers when they develop appropriate application of various proteins in food products.

Functional Properties of Select Dry Bean Seeds and Flours

Select functional properties of 21 dry beans and soybean seeds and their corresponding flours were evaluated. Among the tested seeds, dark-red and light-red kidney beans had larger length (L)/breadth (B) ratios than the rest. Lentil seeds were the smallest (L/B = 0.98), thinnest (2.23 mm), and lightest (density 1.14 g/cm3 ) among the tested seeds. Garbanzo seeds were the thickest (thickness 7.05 mm). Highest bulk density (g/cm3 ), porosity (%), specific volume (cm3 /g), and bulk volume (cm3 /g) were registered, respectively, by moth bean (0.86 g/cm3 ), pink bean (66.53%), lentil (0.88 cm3 /g), and soybean (1.46 cm3 /g) seeds. Water uptake during soaking peaked in ≤12 hr by all bean seeds. Soybean and black bean flours, respectively, exhibited the highest water-holding (3.14 g/g) and oil-holding (2.15 g/g) capacities. Great Northern bean flour exhibited higher foaming volume (30.8% increase) than all the other tested seed flours. Stability of all bean flour foams were ≤36 hr. Black gram flour formed a gel at the lowest concentration (4% w/v) among all the tested seed flours. Garbanzo, soybean, tepary, and val bean flours failed to form a gel at ≤ 20% (w/v). The results indicate that the tested dry bean flours have great potential as functional ingredients for food formulations.

PRACTICAL APPLICATION

Understanding the functional properties of the dry bean seeds and flours is important for designing handling, transportation, storage, and processing methods for these beans and in guiding the selection of appropriate dry bean flours as food ingredients.

Effect of ultrasound treatment on the properties of nano-emulsion films obtained from hazelnut meal protein and clove essential oil

Hazelnut meal protein (4% (w/v)) and clove essential oil (CEO) (3% (v/v)) were homogenized with ultrasound (US) at different times (2, 4 and 6 min) and amplitudes (50, 75 and 100%) to obtain nano-emulsion films. Film forming nano-emulsions (FFNs) were analyzed for average particle size (D_z) and zeta potential, and edible film characterization were evaluated depending on US treatment, as well as antibacterial and antioxidant activities. D_z values and zeta potential of FFNs decreased with increasing acoustic energy delivered to nano-emulsion system. Thickness and water solubility of films significantly decreased with increasing US treatment. Films became more transparent depending on US treatment probably due to particle size reduction. Tensile strength (TS) of films significantly increased with US treatment, while elongation at break (EAB) slightly increased. Microstructure of films became more homogeneous after US treatment and caused to lower water vapor permeability. Enrichment with CEO has given the films antibacterial activity against L. monocytogenes, B. subtilis, S. aureus, P. aeruginosa and E. coli, and antioxidant activity, and US application has improved these activities. US technology can be used to improve mechanical, barrier and antimicrobial properties of hazelnut meal protein based edible films enriched with CEO.

Effects of the Maillard Reaction on the Immunoreactivity of Amandin in Food Matrices

Amandin is the major storage protein and allergen in almond seeds. Foods, containing almonds, subjected to thermal processing typically experience Maillard browning reaction. The resulting destruction of amino groups, protein glycation, and/or denaturation may alter amandin immunoreactivity. Amandin immunoreactivity of variously processed almond containing foods was therefore the focus of the current investigation. Commercial and laboratory prepared foods, including those likely to have been subjected to Maillard browning, were objectively assessed by determining Hunter L^* , a^* , b^* values. The L^* values for the tested samples were in the range of 31.75 to 85.28 consistent with Maillard browning. Three murine monoclonal antibodies, 4C10, 4F10, and 2A3, were used to determine the immunoreactivity of the targeted samples using immunoassays (ELISA, Western blot, dot blot). The tested foods did not exhibit cross-reactivity indicating that the immunoassays were amandin specific. For sandwich ELISAs, ratio (R) of sample immunoreactivity to reference immunoreactivity was calculated. The ranges of R values were 0.67 to 15.19 (4C10), 1.00 to 11.83 (4F10), and 0.77 to 23.30 (2A3). The results of dot blot and Western blot were consistent with those of ELISAs. Results of these investigations demonstrate that amandin is a stable marker protein for almond detection regardless of the degree of amandin denaturation and/or destruction as a consequence of Maillard reaction encountered under the tested processing conditions.

PRACTICAL APPLICATION

Foods containing almond are often subjected to processing prior to consumption. Amandin, the major allergen in almond, may experience Maillard reaction. Understanding the change in amandin immunoreactivity as a result of Maillard reaction is important for amandin detection and production of hypoallergenic food products.

The nexus of food, energy, and water

The Earth's population is expected to exceed 9 billion by 2050, posing significant challenges in meeting human needs while minimally affecting the environment. To support this population, we will need secure and safe sources of food, energy, and water. The nexus of food, energy, and water is one of the most complex, yet critical, issues that face society. There is no more land to exploit, and the supply of fresh water in some areas of the world limits the use of land for food. All solutions must also deal with the overlay of global climate change. Meeting current and future populations needs will require security in food, energy, and water supplies. A nexus approach is needed to improve food, energy, and water security integrating the management of the limited resources while transitioning to a more "green" economy, which provides adequate food, energy, and water for the expanding human population.

Turkish Tombul hazelnut (Corylus avellana L.) protein concentrates: functional and rheological properties

Turkish Tombul hazelnut consumed as natural or processed forms were evaluated to obtain protein concentrate. Defatted hazelnut flour protein (DHFP) and defatted hazelnut cake protein (DHCP) were produced from defatted hazelnut flour (DHF) and defatted hazelnut cake (DHC), respectively. The functional properties (protein solubility, emulsifying properties, foaming capacity, and colour), and dynamic rheological characteristics of protein concentrates were measured. The protein contents of samples varied in the range of 35-48 % (w/w, db) and 91-92 % (w/w, db) for DHF/DHC and DHFP/DHCP samples, respectively. The significant difference for water/fat absorption capacity, emulsion stability between DHF and DHC were determined. On the other hand, the solubility and emulsion activity of DHF and DHC were not significantly different (p > 0.05). Emulsion stability of DHFP (%46) was higher than that of DHCP (%35) but other functional properties were found similar. According to these results, the DHCP could be used as DHFP in food product formulations. The DHFP and DHCP samples showed different apparent viscosity at the same temperature and concentration, the elastic modulus (G' value) of DHPC was also found higher than that of DHFP samples.

Cloning and characterization of an 11S legumin, Car i 4, a major allergen in pecan

Among tree nut allergens, pecan allergens remain to be identified and characterized. The objective was to demonstrate the IgE-binding ability of pecan 11S legumin and characterize its sequential IgE-binding epitopes. The 11S legumin gene was amplified from a pecan cDNA library and expressed as a fusion protein in Escherichia coli. The native 11S legumin in pecan extract was identified by mass spectrometry/mass spectrometry (MS/MS). Sequential epitopes were determined by probing the overlapping peptides with three serum pools prepared from different patients' sera. A three-dimensional model was generated using almond legumin as a template and compared with known sequential epitopes on other allergenic tree nut homologues. Of 28 patients tested by dot blot, 16 (57%) bound to 11S legumin, designated Car i 4. MS/MS sequencing of native 11S legumin identified 33 kDa acidic and 20-22 kDa basic subunits. Both pecan and walnut seed protein extracts inhibited IgE binding to recombinant Car i 4, suggesting cross-reactivity with Jug r 4. Sequential epitope mapping results of Car i 4 revealed weak, moderate, and strong reactivity of serum pools against 10, 5, and 4 peptides, respectively. Seven peptides were recognized by all three serum pools, of which two were strongly reactive. The strongly reactive peptides were located in three discrete regions of the Car i 4 acidic subunit sequence (residues 118-132, 208-219, and 238-249). Homology modeling of Car i 4 revealed significant overlapping regions shared in common with other tree nut legumins.