Functional properties of protein isolates,globulin and albumin extracted from Ginkgo biloba seeds

In this study, the functional properties of Ginkgo seed protein isolate (GPI), Ginkgo seed globulin protein (GGP) and Ginkgo seed albumin protein (GAP) extracted from Ginkgo biloba seeds were investigated. The protein contents of GPI, GGP and GAP were 91.0%, 93.4% and 87.8%, respectively in the samples in which the sugar, polyphenol and crude fibre were removed by the preparation procedure. For functional properties of Ginkgo seed proteins in the natural state, GAP showed the highest oil-absorption capacity (9.3 ml/g), foaming capacity (67.8%), emulsifying capacity (65.4%) and emulsion stability (90.6%); while GPI showed the highest water absorption capacity (1.93 ml/g), and GGP showed the highest foam stability (55.5%). The differences of the chemical components, surface hydrophobicity, disulphide bond (SS) and sulfhydryl group (SH) contents of GPI, GGP and GAP, which were correlated significantly with functional properties of Ginkgo seed proteins, were also investigated. The improved functional properties, such as water absorption capacity, solubility, foaming properties and emulsifying properties of Ginkgo seed proteins were observed in a pH range of 8.0–10.0 or sodium chloride concentration of 0.5–0.75 M.     

Potential of pulse-derived proteins for developing novel vegan edible foams and emulsions

Chefs around the world strive to go beyond ordinary and garnish dishes with edible foams and emulsions, generally made using proteins derived from soy or animal sources. However, the increasing number of consumers following a vegan diet has led to a higher demand for novel foods formulated using plant-derived proteins. The current study evaluated the functional properties of proteins obtained by alkaline solubilisation from common pulses. Water- and oil-holding capacities varied within the ranges 2.39–6.78 and 3.46–6.37 g of water or oil per g or protein concentrate, respectively. Emulsifying capacity and stability was higher at pH values 2.0 and 10.0. A similar trend was observed for foaming capacity and stability. Proteins isolated from fava beans showed the highest foaming capacity, calculated as 56.7 ± 2.9 and 56.7 ± 2.7% when measured at pH 2.0 and 10.0, respectively (P < 0.05). Overall, studied proteins showed potential for their use in edible foams, emulsions and other innovative products.     

Endogenous Proteases in Pacific Whiting (Merluccius productus) Muscle as A Processing Aid in Functional Fish Protein Hydrolysate Production

A fish protein hydrolysate (FPH) from Pacific whiting (Merluccius productus) muscle was produced by autolysis of a minced homogenate (8% protein) at pH 7.0 and 60°C, where maximum endogenous proteolytic activity was detected. FPH production was controlled by the pH stat method, yielding a 4.43% degree of hydrolysis after 1 h of autolysis. Upon autolytic processing, 28.9 ± 0.7% of the total protein was found in the soluble fraction. FPH was 100% soluble at pH 7.0 and 10.0 and was less soluble at pH 4 (82.5%, P ≤ 0.05). FPH showed better emulsifying properties than sodium caseinate (SCA) at pH 4.0 (P ≤ 0.05), but had a lower foaming capacity (P ≤ 0.05) than bovine albumin (BSA) at all evaluated pHs. FPH foaming capacity was not affected by pH, however, foam stability was equal or better than that of BSA, especially at pH 4.0 (P ≤ 0.05). These results suggest the possibility of producing FPH with similar or better functional properties than those of functional ingredients, such as SCA and BSA. Furthermore, the data presented support our hypothesis that the high proteolytic activity in Pacific whiting could be used as an advantage in fish protein hydrolysate production or as a processing aid where protein hydrolysis is required.     

Functionality of Bacillus proteinase hydrolysates of sodium caseinate

Sodium caseinate (NaCN) was digested with Protamex, a Bacillus proteinase, at 40°C and pH 7.0 to degree of hydrolysis (DH) values of 2.7%, 5.3% and 13.3%. The solubility, emulsifying, foaming and viscosity properties of the hydrolysates were investigated between pH 2.0 and 10.0. Foam expansion of >1300% was observed for the 5.3% DH hydrolysate at pH 4.0, compared to 670% for unheated NaCN. Significantly improved foam expansion properties (P<0.005) were observed over the entire pH range examined for the 13.3% DH hydrolysate compared to unheated or heat-treated NaCN. Hydrolysis resulted in significantly improved solubility (P<0.005) around the isoelectric point and significant improvements in the emulsifying activity and stability (P<0.005) at alkaline pH compared to unheated NaCN. Hydrolysis with Protamex increased the apparent viscosity of NaCN at the isoelectric point. Reversed-phase HPLC profiles showed that high DH samples contained high levels of hydrophilic peptides.     

Physicochemical and Functional Properties of Tea Protein

Tea protein has received much attention due to its potential health functions. This article studied the molecular weight, foaming capacity, foam stability, emulsifying capacity, emulsion stability, and oil absorption of tea protein prepared from tea residue by alkali extraction. The results showed that tea protein contained two components with different molecular weights (1.26 × 10⁶ ± 1.3 × 10⁴ and 2.4 × 10⁴ ± 1.1 × 10³). The content of the lower molecular component in tea protein was higher than the higher molecular one. When the concentration of tea protein was 4 mg/mL, its sparkling ability was satisfied, while the foaming capacity and foam stability was the best, respectively, at the conditions of pH 9 and 7. The emulsifying capacity was 62 ± 2% as well as 99 ± 1% of emulsion stability, and oil absorption was 170 ± 7%.     

Effect of pH on phosphorylation of potato protein isolate

Potato protein isolate (PPI) was phosphorylated with sodium trimetaphosphate (STMP) at ambient temperature and various reaction pH (5.2, 6.2, 8.0 and 10.5) to improve the functional properties without impairing the nutritional availability. Changes in chemical composition (total and coagulable protein content, ash and minerals content and amino acid composition), functional properties (protein solubility index, emulsifying activity and foaming capacity, water and oil absorption capacity) and phosphorus were determined. The chemical composition and functional properties of phosphorylated potato protein isolate (PP-PPI) were significantly different (p < 0.05). The PP-PPI at pH 5.2 was characterised by the highest content of all amino acids, whereas, PP-PPI under alkaline conditions (pH 10.5) caused decrease in these compounds. PP-PPI at pH 8.0 had the highest oil absorption capacity, emulsion activity and foam capacity, whereas, PP-PPI at pH 10.5 had the highest WAC.     

Functional properties of protein hydrolysates from pea (Pisum sativum,L) seeds

The aim of this study was to investigate the effects of partial enzymatic hydrolysis on functional properties of two different pea protein isolates obtained from two pea genotypes, Maja and L1. Papain and commercial protease (Streptomyces griseus protease) were used for protein modification. Solubility, emulsifying and foaming properties were estimated at four different pH values (3.0, 5.0, 7.0 and 8.0). Papain increased solubility of L1 pea protein isolate at pH 3.0, 5.0 and 8.0, emulsifying properties and foaming capacity at all pH values. Otherwise, papain increased solubility of Maja pea protein isolate only at pH 8.0. This pea protein isolate modified with both enzymes formed emulsions with improved stability at lower pH (3.0, 5.0). The commercial protease‐prepared pea protein isolates showed generally low solubility and different emulsifying and foaming properties. Proper selection of enzyme, conditions of hydrolysis and genotypes could result in production of pea protein isolates with desirable functional properties.     

Functional properties of protein concentrates and isolates produced from cashew (Anacardium occidentale L.) nut

Protein isolates and concentrates were obtained from defatted cashew nut powder by two methods: alkaline extraction-isoelectric precipitation (IP) and alkaline extraction-methanol precipitation (MP). The functional properties of cashew nut protein isolates, concentrates and powder were significantly different (p < 0.05). Cashew nut protein isolate (CNPI) had higher water and oil absorption capacities (2.20 ml/g and 4.42 ml/g, respectively), emulsifying stability index (447%), foam capacity and stability (45% and 55%, respectively), and least gelation capacity (13.5%) than cashew nut protein concentrate (CNPC), which was also higher than that of defatted cashew nut powder (DCNP). However, emulsifying activity index (12.45%) and bulk density (0.31) of CNPI were lower than that of CNPC, which were also lower than that of DCNP. The water solubility of CNPI (95%) and CNPC (95%) was not significantly different (p > 0.05) among the samples, but was significantly different (p < 0.05) from that of DCNP (75%). The CNPI, CNPC and DCNP showed decreasing solubility with decreasing pH, with the minimum solubility being observed at a pH range of 4.0–4.5, confirming the isoelectric point of cashew proteins. However, higher water solubility, emulsifying activity, and foaming property were observed at an alkaline pH than at an acidic pH in all samples.     

Functional properties and antioxidative activity of protein hydrolysates from toothed ponyfish muscle treated with viscera extract from hybrid catfish

Functional properties and antioxidative activity of a protein hydrolysate prepared from toothed ponyfish (Gazza minuta) muscle, using viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus), with a degree of hydrolysis (DH) of 70%, were investigated. The protein hydrolysate had a good solubility. It was soluble over a wide pH range (3–9), in which more than 77% solubility was obtained. The emulsifying activity index of the protein hydrolysate decreased with increasing concentration (P < 0.05). Conversely, the foaming abilities increased as the hydrolysate concentrations increased (P < 0.05). Protein hydrolysate exhibited the increases in 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) radical scavenging activities, ferric reducing power (FRAP) and metal chelating activity as hydrolysate concentration increased (P < 0.05). ABTS radical scavenging activity of protein hydrolysate was stable when heated at 100 °C for 180 min and subjected to a wide pH range (1–11). Therefore, protein hydrolysate from the muscle of toothed ponyfish produced by viscera extract from hybrid catfish can be used as a promising source of functional peptides with antioxidant properties.     

Protein solubility and emulsifying capacity in frozen stored fish mince

Effect of initial freshness on the relationship between emulsifying capacity and protein solubility of frozen stored fish mince was investigated. The emulsifying capacity of proteins was significantly (P <0.05) affected by the initial freshness. A positive correlation (P <0.05) between protein solubility and the ability of the soluble proteins to emulsify and stabilise an emulsion was observed. Correlation between salt-soluble proteins and emulsifying capacity revealed that myofibrillar proteins (P <0.05) are the main proteins that decide the emulsion properties.     

Antioxidant activity and functional properties of porcine plasma protein hydrolysate as influenced by the degree of hydrolysis

Antioxidant activity and functional properties of porcine blood plasma protein hydrolysates (PPH) prepared with Alcalase at 6.2%, 12.7% and 17.6% of degree of hydrolysis (DH) were investigated. The PPH showed stronger radical-scavenging ability and possessed stronger Cu²⁺-chelation ability and a reducing power compared to non-hydrolysed plasma protein (P < 0.05). The antioxidant activity of PPH, indicated by thiobarbituric acid-reactive substance (TBARS) values in a liposome-oxidising system, increased with increasing DH (P < 0.05). The Alcalase hydrolysis increased protein solubility from its original 68.46–81.79% (non-hydrolysed) to 82.95–94.94% (hydrolysed) over a broad pH range (3.0–8.0). However, hydrolysis decreased surface hydrophobicity and suppressed emulsifying and foaming capacity of the plasma protein. To identify antioxidant peptide, PPH was subjected to ultrafiltration, ion-exchange chromatography and reverse-phase high performance liquid chromatography (RP-HPLC), and the amino acid sequences of isolated peptides were determined by liquid chromatography/tendem mass spectrometry (LC–MS/MS). The peptide with the strongest antioxidant activity had the amino acid sequence of His-Asn-Gly-Asn. The results indicated that PPH could be used as a novel antioxidant but may be of limited utility as an emulsifying or foaming agent.     

Optimization of trypsin-assisted extraction,physico-chemical characterization,nutritional qualities and functionalities of palm kernel cake protein

The extraction of palm kernel cake protein (PKCP) was enhanced by trypsin-assisted assay. From the Response Surface Methodology (RSM) generated model, the optimum conditions were using trypsin at concentration 1.36 g/100 g, reacted on palm kernel cake (PKC) slurry (1.1 g/100 mL) at 50 °C and pH 9.5. The trypsin extracted protein yield (61.99 ± 0.74 g/100 g) was significantly (P < 0.05) higher than the alkaline (pH 9.5) method (10.21 ± 0.24 g/100 g). Surface hydrophobicity of PKCP (159.36) was significantly (P < 0.05) higher than soy protein isolate (SPI) (51.51). PKCP had a lower denatured temperature (66.88 °C) than SPI (101.41 °C). The electrophoretograms of PKCP showed 3 bands at 2.20, 3.51 and 4.28 kDa, compared to SPI which had 22 bands with molecular weight ranging from 2.00 to 82.79 kDa. Except lysine, the essential amino acids of PKCP met the suggested requirements of FAO/WHO for 2–5 year old infants. The in-vitro digestibility, essential amino acids/total amino acids (E/T) value, biological value and computed-protein efficiency ratio (C-PER) value for PKCP were significantly (P < 0.05) higher than that of SPI. PKCP also showed better solubility (30.12–97.79 vs. 9.15–69.78 g/100 g) emulsifying activity (143.25 vs. 32.57 m²/g); but lower emulsifying stability (37.83 vs. 43.08%), foaming capacity (22.5 vs. 100.0 ml/100 ml) and foam stability (3.70 vs. 19.20 ml) than the SPI.     

Changes in physicochemical and functional properties of whey protein concentrate upon succinylation

The highest degree of succinylation was achieved at the level of 6 moles of succinic anhydride/mole of lysine in whey protein concentrate (WPC). Structural modification of protein or the presence of a high negative charge on the surface of protein upon succinylation exposed buried hydrophobic sites. The solubility of succinylated protein derivatives increased at alkaline pH but decreased at acidic pH values as compared to native WPC. The physicochemical properties of succinylated protein derivatives, such as water– and oil– binding capacity, viscosity and emulsion properties increased significantly (P < 0.05) compared to native WPC, whereas, foaming stability reduced significantly (P < 0.05) and there was no change in the foaming capacity.     

Physicochemical and techno-functional properties of acid-aided pH-shifted protein isolate from over-salted duck egg (Anas platyrhucus) albumen

Here, potential physicochemical and techno-functional properties of the albumen protein recovered from over-salted albumen by an effective acid-aided pH-shift process (POA) were tested in comparison with the fresh albumen (FA) and albumen protein recovered from fresh albumen by acid-aided pH-shift process (PFA). POA contained 66.73% protein and 11.30% sodium (dry basis). Surface hydrophobicities of PFA and POA were higher than FA (P < 0.05), whereas the reactive sulfhydryl content of FA was higher than PFA and POA (P < 0.05). PFA had the highest whiteness followed by POA and FA, respectively. Single endothermic peak in DSC thermogram was found at 86.86, 89.67 and 98.96 °C for FA, PFA and POA, respectively. Long-term salting impaired the solubility, viscosity, emulsifying activity and gelation but not for foaming of albumen protein isolate. FA can be softly gelled with continuously packed structure, whereas PFA and POA underwent agglutination to form white clot suspension with spongy network.     

Amino acid profile,protein digestibility,thermal and functional properties of Conophor nut (Tetracarpidium conophorum) defatted flour,protein concentrate and isolates

Functional properties, amino acid compositions, in vitro protein digestibility, electrophoretic and thermal characteristics of conophor defatted flour (CDF), conophor protein concentrate (CPC), isoelectric protein isolate (CII) and neutral protein isolate (CNI) were evaluated. The isolates (CII and CNI) showed significantly lower (P < 0.05) water and oil absorption capacities, emulsifying and gelling capacities, but higher emulsion stability and foaming capacity. In vitro protein digestibility, enthalpy and denaturation temperature varied between 52.28% and 73.4%, 1.62–4.04 J g^?1 protein and 79.7–89.3 °C, respectively. The native proteins were comprised of subunits with molecular weights ranging between 15.3 and 129.3 kDa. The major amino acids in all the samples were aspartic acid, glutamic acid and arginine, whereas the percentages of essential amino acids in CDF, CPC, CII and CNI were 39.35%, 40.46%, 44.54% and 46.04%, respectively. Conophor protein products could be used as functional ingredients in food formulations and for enriching low quality protein diets.     

Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

Functional properties of gelation-like protein hydrolysates from scallop (<Emphasis Type="Italic">Patinopecten yessoensis</Emphasis>) male gonad

Gelation-like protein hydrolysates from scallop (Patinopecten yessoensis) male gonad (SMG) were obtained by enzymatic hydrolysis using neutrase. Functional properties of SMG hydrolysates (SMGHs) with different degree of hydrolysis (DH: 4.94, 6.84, 7.53 and 11.86%, respectively) were evaluated with the objective to investigate the relations between hydrolysis characteristics and functionalities. The results showed that hydrolysis with neutrase improved the gelation property, solubility, water-holding capacity (WHC), oil-holding capacity (OHC), and surface hydrophobicity (SH), but not foaming capacity (FC) of SMG. The SMGHs at high DH (11.86%) showed better gelation property and solubility than that at low DH (4.94–7.53%). However, the maximum values of WHC, OHC, and SH of SMGHs were found at DH of 4.94%, significantly higher than (p < 0.05) or equivalent to (p > 0.05) that of soy protein isolate (SPI) for WHC and OHC. Emulsifying capacity of SMGHs is independent of DH, but restricted by pH environment. The emulsifying activity index of all SMGHs was significantly higher than that of SPI in pH 5 (p < 0.05) and slightly higher than or equivalent to that of SPI in pH 7. Meanwhile, SMG and SMGHs were abundant in glycine, lysine, alanine, glutamic acid, and aspartic acid, containing all the essential amino acids (41.63–42.90% of the total amino acids). These results imply that SMGHs might be utilized as multifunctional and nutritive ingredients in food industry.     

Characteristics and Functionality Enhancement by Glycosylation of Bitter Melon (Momordica charantia) Seed Protein

Seeds of ripe bitter melon (Momordica charantia) contain approximately 30% protein. However, this protein, which is less functional than soy protein, may have desirable functionalities as a food ingredient after modification. Bitter melon seed protein isolate (BMSPI) was prepared under optimal extraction conditions (defatted meal to 1.3 M NaCl was 1:10 w/v; pH 9.0) and its functional properties were investigated before and after modification by glycosylation. Glycosylation was conducted at varying relative humidities (50%/65%/80%) and temperatures (40 °C/50 °C/60 °C) using a response surface central composite design. Degree of glycosylation (DG) ranged from 39.3 to 52.5%, 61.7 to 70.9%, and 81.2 to 94.8% at 40 °C, 50 °C, and 60 °C, respectively (P values < 0.0001). Denaturation temperatures of all DGs ranged from 111.6 °C to 114.6 °C, while unmodified/native BMSPI had a value of 113.2 °C. Surface hydrophobicity decreased to approximately 60% when the DG was maximal (94.8%). Solubility decreased almost 90% when the DG was maximal in comparison to the native BMSPI (62.0%). Emulsifying activity increased from 0.35 to 0.80 when the DGs were ≥80%, while emulsion stability increased from 63 to 72 min when the DGs were greater than 70%. A similar trend was observed with foaming capacity and foaming stability of the glycosylated proteins. This glycosylated BMSPI with improved emulsifying and foaming properties could be used as an ingredient in food products where such properties are required.     

Nutritional and functional characterisation of hydrolysates from quinoa flour (Chenopodium quinoa) using two proteases

The objective was to study the nutritional and functional properties of hydrolysates from quinoa (Chenopodium quinoa) obtained by enzymatic hydrolysis of defatted quinoa flour (DQF). The commercial enzymes alcalase and flavourzyme were used to obtain the hydrolysates defatted quinoa flour hydrolysate with alcalase (DQFA) and defatted quinoa flour hydrolysate with flavourzyme (DQFF), respectively, after 3 h of digestion at 50°C and pH 8. The degree of hydrolysis (47.32%), yield (31.05%) and protein recovery (88.80%) values were higher in DQFA; however, its protein content (48.34%) was lower compared to that of DQFF (55.06%). Also, DQFA had a solubility greater than 57% over a wide pH range (2–10) and good foam stability (70–90%). On the other hand, DQFF presented adequate emulsifying activity (61.30 m²/g), emulsifying stability (158.62 min) and foaming capacity (131%). Due to the high content of macro- and micronutrients and adequate emulsifying and foaming properties, DQFA and DQFF could be used as ingredients in various processed food products and protein supplements.     

Effect of the defatting process,acid and alkali extraction on the physicochemical and functional properties of hemp,flax and canola seed cake protein isolates

The effect of the defatting process, acid and alkali extractions on the physicochemical and functional properties of hemp, flax and canola protein isolates was studied. The defatting process enriched the protein content from around 35 to 52–55 % in the defatted oilseed cakes. Further treatment with acid and alkali led to the highest enrichment (P < 0.05) in the protein content (>90 %). The defatting process produced the lightest (P < 0.05) colour compared to the parent oilseed cakes and the protein isolates. Alkali extraction produced protein isolates with the highest (P < 0.05) water holding capacity while the original oilseed cakes had the highest oil holding capacity. Acid and alkali extractions produced protein isolates with the highest emulsifying activity and emulsion stability. The alkaline soluble flax protein isolate and acid hemp protein isolate had the highest (P < 0.05) creaming stability and largest droplet size respectively. Amino acid profiles of protein isolates after acid and alkali extraction were improved, leading to a protein suitable for fortification in food products that meet human nutrition requirements.