Effect of phenolic compounds on the properties of porcine plasma protein-based film

Properties of porcine plasma protein-based film incorporated with tannic acid, caffeic acid and ferulic acid at different concentrations (1–3% (w/w) of protein content) were studied. Film-forming solution (FFS) containing 3% protein (w/v) and 70% glycerol (w/w of protein content) was preheated at 70 °C for 30 min and adjusted pH to 10 followed by the addition of phenols and film casting. Tensile strength (TS) of resulting film increased by 123.3, 194.3 and 19.5% and elongation at break (EAB) increased by 71.1, 86.3 and 10.2%, respectively, compared with the control film, when tannic acid, caffeic acid and ferulic acid at a level of 3% was added. The use of all phenolic compounds slightly increased water vapor permeability (WVP) of resulting films (p < 0.05). The increases in a^∗- and b^∗-values of films were observed as the higher concentrations of tannic acid and caffeic acid were used. This was associated with the lowered transparency of resulting films. FFS containing 3% caffeic acid with prior oxygenation, especially with pH 10, yielded the film with increased TS but lowered EAB (p < 0.05). Oxygenation of FFS was associated with the lower L^∗-value and higher a^∗-value of resulting films. Therefore, phenolic compounds could be used as natural cross-linkers which affected the properties of porcine plasma protein-based film differently.     

Addition of bovine plasma hydrolysates improves the antioxidant properties of soybean and sunflower protein-based films

The effect of adding different amounts of a bovine plasma hydrolysate (BPH) with high antioxidant capacity on the functional properties of protein films based on soybean and sunflower protein was studied. BPH caused a decrease in tensile strength, elastic modulus and glass transition temperature of the films, as well as an increase in their elongation at break and water vapor permeability, without noticeably affect their appearance. These results suggest that this hydrolysate had a plasticizing effect on film properties despite its wide distribution of molecular weights. BPH also conferred important antioxidant properties to protein films. It is noteworthy that the antioxidant capacity of the protein-based films activated with bovine plasma hydrolysate, proved to be the result of the sum of the characteristics of the protein matrix, plus of the characteristics of the hydrolysate, no synergistic or antagonistic effects were observed in this property. The use of vegetable proteins (soybean or sunflower) as a biopolymer for film preparation and its activation with bovine plasma hydrolysate with antioxidant capacity should be an approach for maximization the use of these underused proteins.     

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.     

Monoclonal antibody-based enzyme immunoassay for detection of porcine plasma in fish surimi

Detection of porcine plasma using indirect ELISA was developed using mAb B4E1 for the prevention of their usage in human food that creates religious and health conflicts. The immunoassay has a CV < 20% and did not cross-react to other meat and non-meat proteins. The sensitivity of the assay is 0.25% (w/w) of porcine plasma in spiked raw and cooked fish surimi. The assay did not produce a false positive result for any of the commercial fish surimi tested that were not contain porcine plasma. Determination of a 60-kDa antigenic protein of porcine blood using Western blot confirmed its presence in the plasma fraction of the porcine blood. Further proteomic analysis involving liquid chromatography–tandem mass spectrometry (LC-MS/MS) revealed the 60-kDa protein to be porcine serum albumin.     

Improvement of gelling properties of porcine blood plasma using microbial transglutaminase

The effect of microbial transglutaminase (MTGase) on the texture and water-holding capacity (WHC) of heat-induced gels prepared from porcine blood plasma at pH 5.5 was investigated. Different concentrations of commercial MTGase were added to plasma and incubated for several times under specific conditions of temperature and pH. From the results obtained, it can be postulated that enzymatic treatment enhances textural properties and WHC of plasma gels at pH 5.5, especially when incubated with 3% of the commercial product for 3 h at 30 °C and pH 7. This treatment increased by 0.4 N the hardness of gels and reduced by 3% the water released after gel centrifugation with respect to the control samples. SDS–PAGE confirmed that cross-linking took place when MTGase was added to plasma solutions. However, the results suggest that the sole addition of MTGase was not effective enough to improve the gelling properties of plasma proteins under acidic conditions.     

臭氧等离子体预处理对芳纶染色性能的影响

针对芳纶难以使用常规工艺进行染色和印花加工等问题,通过臭氧等离子体预处理芳纶织物后结合树脂改性以提升染色性能。研究了臭氧等离子体预处理对树脂改性芳纶表面元素和形貌的影响,探究了改性后芳纶织物的分散染料染色效果。结果表明:单独的臭氧等离子体处理对芳纶的染色效果改善并不明显,而臭氧等离子体预处理引入了丰富的活性基团并构建了粗糙的界面,显著提升了树脂的均匀分散性,使树脂和织物间的结合强度最高可提升104%,同时,大大提高了芳纶织物的分散染料上染率(98.6%)和表观染色深度(2.7),染色织物的色牢度得到有效提升,耐摩擦色牢度可达到服装面料使用要求。     

The effect of myofibrillar/sarcoplasmic protein ratios on the properties of round scad muscle protein based film

The effect of the ratios of myofibrillar protein (MP) to sarcoplasmic protein (SP) from round scad (Decapterus maruadsi) muscle on the properties of the resulting films was investigated. Tensile strength (TS) of films decreased with increasing SP content (p < 0.05). Films prepared from MP/SP ratio of 10:0 (w/w) exhibited the highest TS (p < 0.05). Elongation at break (EAB) of films prepared with SP content greater than 30% had the decreased EAB (p < 0.05). Water vapor permeability (WVP) of films increased when SP content increased up to 20% and decreased with increasing SP content up to 30% (p < 0.05). Solubility of films decreased but protein solubility increased with increasing SP contents (p < 0.05). The a*-value and ΔE* of film increased with increasing SP content. Films with all MP/SP ratios exhibited the negligible transmission to the light in UV range. Therefore, it is suggested that the type and ratio of proteins in fish muscle, both SP and MP, influenced the properties of film from round scad muscle. Results suggested that the removal of sarcoplasmic protein from fish muscle by thorough washing was an effective means to improve the mechanical properties as well as color of the fish muscle protein-based film.     

Effectiveness of high pressure processing on the hygienic and technological quality of porcine plasma from biopreserved blood

The effects of a high hydrostatic pressure (HHP) treatment (450MPa, 15min at 20°C) on both the microbiological quality and the functional properties of plasma from biopreserved porcine blood were evaluated. Blood was inoculated with Enterococcus raffinosus-PS99 (10(7)ufcmL(-1)) and stored at 5°C. After 72-h storage, bacterial counts in inoculated samples decreased by 52, 70, 81 and more than 99% for coliforms, Pseudomonas spp, hemolytic and proteolytic bacteria, respectively. Counts of these bacterial groups were undetectable in the final product after pressurization, whereas total lactic acid bacteria were detected at levels up to 10(2)ufcmL(-1). Gelling, foaming and emulsifying properties of the plasma proteins were not noticeably affected by HHP. The results show that it is possible to obtain high-quality and microbiologically stable blood derivatives as functional ingredients, by combining biopreservation and HHP.     

环境湿度对植物蛋白膜的影响研究

研究了环境湿度对小麦蛋白膜、大豆蛋白膜以及小麦-大豆复合膜机械性能、通透性等的影响。结果表明,由于蛋白腹为亲水性膜,受环境湿度的影响,其水分含量、分子间作用力有所不同,从而导致蛋白膜的机械性能、透湿性和吸湿率也随之发生变化。膜的阻止水蒸汽渗透的能力下降,吸湿率降低,透氧率呈上升趋势。     

Determination of androstenone levels in porcine plasma by LC-MS/MS

Androstenone (5α-androst-16-en-3-one) is a major component in boar taint. Here, a liquid chromatography-tandem mass spectrometry method was developed to analyse androstenone in porcine plasma to facilitate studies of its transport from pig testes to adipose tissues. The method used androstanone (5α-andro-stan-3-one) as internal standard, Oasis® MCX solid-phase extraction, C18 reversed-phase column, and API 5000 Triple Quadrupole mass spectrometry with positive electrospray ionisation interface operating in the multiple reaction monitoring mode. Incubation of the plasma samples with β-glucuronidase/arylsulfatase revealed an increase in androstenone yield indicating the presence of a conjugated form of its 3-enol isomer. With this method the limit of detection (LOD) was 1.0 ng and the limit of quantification (LOQ) was 3.3 ng per mL of plasma. In conclusion, the presented method is sensitive and reproducible and thus suitable for accurate quantification of androstenone levels in a small volume of porcine plasma.     

Characteristics and antioxidative activity of Maillard reaction products from a porcine plasma protein–glucose model system as influenced by pH

Maillard reaction products (MRPs) were prepared by heating the solution containing 2% porcine plasma protein (PPP) and 2% glucose adjusted to various pHs (8, 9, 10, 11 and 12) at 100 °C for different times (0, 2, 4, 6 and 8 h). The pH of all MRPs markedly decreased within 2 h of heating time. Browning and intermediate products, as monitored by absorbance at 420 nm and absorbance at 294 nm, sharply increased within 2 h (P < 0.05). Thereafter, slight increases were observed up to 8 h. Fluorescence intensity (Ex 347 and Em 415 nm) sharply increased within the first 2 h with a subsequent decrease when heating time increased (P < 0.05). Increases in browning and formation of intermediate products were concomitant with the decreases in free amino group and reducing sugar contents. Among all MRPs tested, those derived from the PPP–glucose system at pH 12 rendered the highest browning and intermediate products. However, no differences in reducing power or DPPH radical-scavenging activity of MRPs with initial pH ranges of 10–12 were noticeable. Electrophoretic study revealed that cross-linked proteins with high molecular weight were formed in the PPP–glucose model system to a greater extent at pHs 8 and 9, than at pHs 10–12. Nevertheless, heating times had no pronounced effect on protein pattern of glycated proteins.     

Cold storage of porcine plasma treated with microbial transglutaminase under high pressure. Effects on its heat-induced gel properties

The objective of this work was to study the heat-induced gelling properties, at acid pH, of porcine plasma previously treated with microbial transglutaminase (MTGase) under high pressure (HP), when kept under refrigeration conditions for different times (setting time). The results indicated that, although the cross-linking activity of MTGase was enhanced under pressure, consequently, improving the thermal gel texture, the most significant effects, particularly on gel hardness, were obtained by keeping the treated plasma solutions under refrigeration for at least 2 h before gelation. On the whole, under such conditions, increases of approximately 60% of this textural parameter, calculated on the basis of the values corresponding to the heat-induced non-treated plasma gels at pH 5.5, were achieved. However, from the SDS–PAGE profiles, it can be suggested that mechanisms other than polymerisation by MTGase explain the beneficial effects of the treated plasma cold storage on gel texture. In contrast, the setting time had no effects on the water-holding capacity of heat-induced plasma gels at acid pH value, although this gel property was slightly enhanced by submitting porcine plasma solutions to the combined treatment (MTGase plus HP), with improvements being in accordance with the better-structured network of these heat-induced plasma gels.     

Effect of porcine plasma protein and setting on gel properties of surimi produced from fish caught in Thailand

Effects of porcine plasma protein (PPP) and high temperature setting on gel properties of surimi from bigeye snapper, bigeye croaker, threadfin bream and barracuda were investigated. PPP was effective in increasing breaking force and deformation of kamaboko gels set at 40°C for 30 min and heated at 90°C for 20 min. The optimum levels of PPP were 0.5, 0.5, 1.5 and 1.5 g/100 g and the optimum setting times were 2, 1.5, 1.5 and 2 h for bigeye snapper, bigeye croaker, threadfin bream and barracuda surimi, respectively. However, the addition of PPP significantly decreased whiteness (P<0.05). An increase in gel-forming ability of surimi with PPP coincided with a decrease in solubility in mixture of SDS, urea and β-mercaptoethanol, indicating the formation of nondisulfide covalent bond induced by both endogenous and plasma transglutaminase. The results supported that PPP improve the gelation of surimi in combination with setting.     

Effect of inverted saccharose on some properties of honey

In this study, three groups of honey [natural honey; honey produced by the supplementary feeding of bees with saccharose syrup (SSH) and heat and acid (88 °C, 2 h; 0.1% HCl) treated saccharose syrup honey (ISSH)] were produced and physicochemical (water content, pH, free acidity, ash, HMF, diastase activity, sucrose, protein and viscosity), microbiological and sensory properties of these honeys were determined. Also, mineral contents of the honeys were measured. Moisture and ash contents of SSH were higher, acidity level was lower than those of other honeys. The mineral content of natural honey was higher than that of the others, except for Pb and Zn. Diastase activity of ISSH was below the standard limit and HMF content of this honey was high, but not exceeding the limit. Supplementary feeding of honey bees with inverted (acid and heat treatment) saccharose yielded a honey which had a higher HMF content and a lower diastase activity, moisture content and free acidity than natural honey or SSH.     

Effect of solution pH on solubility and some structural properties of soybean protein isolate films

Changes in solubility and molecular properties of protein films obtained from soy protein isolate (SPI) solutions at different pH values (2, 8 and 11) were investigated to study protein behavior during film formation. Proteins retained their native conformation in films at pH 8, but were partially or extensively denatured at pH 11 and 2. Although film protein networks were maintained by the same type of interactions at different pH values—covalent (disulfide bonds) and non‐covalent bonds (especially hydrophobic interactions and hydrogen bonds)—the intensity of each type of interaction (predicted from solubility tests in buffers with different chemical action) depended on the pH of the initial solution. Films obtained at pH 8 presented the highest solubility in all the buffers, whereas films at formed pH 2 presented the lowest, except in the buffer of pH 8 that contained urea, SDS and 2‐mercaptoethanol, which totally dissolved 100% of the film proteins. Films prepared at extreme pH values had a denser microstructure than those at pH 8. SDS–PAGE patterns indicated that films were mainly formed by β‐conglycinin and glycinin, which aggregated in different forms during film formation, depending on the pH of the initial solutions. Some of these proteins remained weakly bonded and/or were held by the network of films. These differences in the protein networks structure would affect the physical, mechanical and barrier properties of the films. Copyright © 2006 Society of Chemical Industry     

Native and modified porcine plasma protein as wall materials for microencapsulation of natural essential oils

Porcine plasma protein (PPP) is of interest as a wall material to encapsulate lemongrass oil, turmeric oil and eucalyptus oil using emulsion technique and freeze drying. The properties of microcapsules were used to evaluate two types of wall material (native porcine plasma protein; NPPP and modified porcine plasma protein; MPPP) at two different ratios of wall material (W) and core material (C) (W:C; 4:1 and 3:1). All NPPP and MPPP emulsions showed Bingham plastic fluid flow behaviours. Moreover, MPPP microcapsules showed lower free oil content on their surface (0.10–0.50%) with higher encapsulation efficiency (91–98%). Fourier-transform infrared spectroscopy showed the outstanding chemical structure of microcapsules. Furthermore, scanning electron microscopy indicated holes on the surface of microcapsules encapsulated with essential oils. Both PPPs can be used as encapsulation material for natural extract and food additives to improve the food texture and as a biopolymer film to maintain the quality of food products.     

Protein co-precipitates from milk and blood plasma: Preparation and investigation of some functional properties

Various processing methods were investigated for the production of milk and porcine blood plasma co-precipitates. Factors considered included pH and temperature treatments as well as the ratio of milk to plasma proteins in mixtures of the raw materials. The recovery of protein in precipitates was measured and the following method was selected accordingly for further studies: pH adjustment of skim milk and blood plasma mixtures to pH 9.5, heating to 70° C, readjustment of pH to 9.5, holding for 3 min, cooling to 68°C, pH adjustment to 3–5, holding for 5 min, cooling to ambient temperature and final pH adjustment to 4.7. Two co-precipitates (70/30 M/P and 30/70 M/P) were prepared from a 70:30 and a 30:70 mixture of skim milk (M) and blood plasma (P). Some of the functional properties of these preparations were measured and compared with those of total milk protein (TMP) and blood plasma precipitate (P) prepared by the same procedure as well as acid-precipitated casein. The protein contents of preparations freeze-dried at pH 7.0 varied between 91.5 and 92.3% and those freeze-dried at pH 4.7 varied between 93.1 and 96.0%. The solubility profile and emulsifying capacity of the 70/30 M/P compared favourably with those of caseinate and TMP. The solubilities of 30/70 M/P and 100% P were, however, poor. The viscosity of solutions of 70/30 M/P was considerably higher than those of caseinate and TMP solutions. Water adsorption isotherms of protein preparations were constructed and are presented in graphical form. Precipitates freeze-dried at pH 7.0 adsorbed more moisture than the same preparations freeze-dried at pH 4.7. These differences were especially evident a water activities >0.8.     

Effect of ultrasonic pretreatment on the antioxidant properties of porcine liver protein hydrolysates

In this study, the effect of ultrasonic pretreatment on the antioxidant activity of porcine liver protein hydrolysates (PLPHs) was investigated. The results showed that the degree of hydrolysis (DH) and peptide contents of the PLPHs increased as the time of ultrasonication increased. The hydrolysate pretreated with ultrasonication for 60 s exhibited the highest DH and peptide contents. The hydrolysate pretreated with ultrasonication for 45 s exhibited the highest ferrous ion chelating ability and reducing power. The hydrolysate pretreated with ultrasonication for 30 s exhibited the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and the higher inhibitory activity in the linoleic acid autoxidation system. The molecular weight of peptides in the hydrolysates was less than 6.2 kDa. The results clearly demonstrated that ultrasonic pretreatment enhances the antioxidant activities of the PLPHs in a short period of time (15–30 s).     

Development of a single-step precipitation cleanup method for the determination of enrofloxacin,ciprofloxacin, and danofloxacin in porcine plasma

In this study, we describe a newly developed and simple analytical method using high-performance liquid chromatography coupled to fluorescence detector (HPLC-FLD) for the determination of enrofloxacin, ciprofloxacin, and danofloxacin in porcine plasma. A single-step sample preparation, including extraction with acidic acetonitrile, coagulation with ammonium acetate, and centrifugation made possible the direct analysis of plasma samples without the need for any further cleanup procedure. The developed method was validated with specificity, linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and precision. All results were fully adequate. In the study using porcine plasma incurring enrofloxacin, the developed method proved capable of quantifying concentrations below its maximum residue limit, and its time-course residues were excreted within the 10-day withdrawal time.