Gel Forming Research Articles

OPTIMIZATION OF ENZYMIC EXTRACTION OF EDIBLE GELATIN FROM CATTLE BONES USING RESPONSE SURFACE METHODOLOGY (RSM)

Gelatin is a protein hydrocolloid. Because of its unique characteristics such as gel forming, thickening, stabilizing, emulsifiing, foam and film forming, is widely used in food industries. In this research, in order to optimize the factors which affect enzymatic extraction method of gelatin ,the effects of three variables, enzyme concentrations(2-10 ppm), time(8-16 hours) and temperature(60-80 ˚C) on the yield of extraction, gel strength, viscosity and absorption in 420 nm were investigated. The rotatable central composite experimental design was used, and the data were analyzed by using of response surface regression(RSREG).Correlation coefficients of fitted regression models of yield, gel strength, viscosity and absorption for enzyme extraction method were determined as 0.953 , 0.998 , 0.995 and 0.935 , respectively.Analysis of variance for the overall effects of process variables in enzymatic extraction method on regression models showed that the enzyme concentration, the time of enzyme treatments and temperature had significant effects on gel strength and viscosity regression models, however the effect of temperature on both yield and absorption regression models was not significant(p > 0.05).The optimum conditions obtained from response surface regression models in enzymatic extraction method for yield, gel strength, viscosity and absorption which were verified experimentalls were (6.1 ppm, 15.6 hours, 70 ˚C), (9.1 ppm, 11.9 hours, 70.3 ˚C), (7.86 ppm, 14.9 hours, 77.5 ˚C) and (2.8 ppm, 10 hours, 60 ˚C), respectively. Key words: gelatin, enzymatic extraction, response surface optimization

Effects of transglutaminase, tyrosinase and freeze-dried apple pomace powder on gel forming and structure of pork meat

Effects of microbial transglutaminase (mTG), mushroom tyrosinase and an apple powder containing transglutaminase (TG) and polyphenol oxidase (PPO) on the structure of industrial pork meat homogenate were studied. Apple powder and mTG both increased the value of storage modulus ( G′). Mushroom tyrosinase was not able to affect gel forming with the used dosages and treatment conditions. All the enzymes studied were able to improve gel hardness of unheated meat homogenate at 4 °C to a certain extent. In gel hardness measurements added cysteine affected positively on the apple powder—treated pork meat and negatively on mTG—and tyrosinase-treated meat. Surprisingly cysteine addition nullified also the action of mTG. Hence powdered apple pulp, a recovered co-product of an industrial process, may contain suitable enzyme activities for food protein stabilization.

English

Bambarra groundnut starch was fractionated into amylose and amylopectin fractions, and chemical modifications, through oxidation and acetylation, was applied to the amylose fraction. Percentage yield of amylose and amylopectin were 75% and 11% respectively. Proximate analysis revealed that percentage protein, ash, crude fibre and crude fat were below 1%. Swelling capacity and solubility of all the samples increased with increasing temperature. Water and oil absorption capacity revealed that hydrophobic tendency was greater than hydrophilic potentials. Gel forming capacity increased with increase in concentration of the samples and least gelation concentration was minimal in amylopectin fraction. Initial pasting temperature of native amylose reduced from 70oC to 60oC and 65oC following oxidation and acetylation, respectively. Among the samples, highest pasting temperature was recorded in native amylopectin and values for peak viscosity during heating (Pv), hot paste viscosity at 95oC (Hv), viscosity after 30 min holding at 95oC (Hv30), cold paste viscosity (Cv), set back (SB) and breakdown (BD) were maximal in native amylose.   Key words: Bambarra groundnut, amylose, amylopectin, modifications.

Effect of Setting Temperatures and Time on the Gelation Properties (Suwari and Modori Phenomena) of Surimi from Mechanically Deboned Chicken Meat

This study was carried out to investigate gel forming and degradation properties (suwari and modori phenomena) of chicken surimi from mechanically deboned chicken meat (MDCM) at various setting temperatures and time. Chicken surimi was manufactured by a continuous process including chopping of MDCM, washing with 5% NaCl solution or pure water, standing, straining and centrifuging etc. Total process of washing for the MDCM from chopping to centrifuging was repeated over 3 cycles. Gel from prepared surimi were formed at 90°C for 30 min after various setting treatments. The textural properties of gels were measured at the temperature ranges of low (10°C), medium (25°C and 30°C) and high (45 to 70°C). The compressive force (CF), hardness and fracturability of surimi gel at 10°C increased as setting time increased, and showed the highest value at 30 h of setting time. The CF and hardness of chicken surimi gel at 25°C and 30°C showed the highest values at 10 h of setting time. Most of gel strengths including CF, and texture profile analysis (TPA) values showed the highest levels in the range 47.5 to 52.5°C (p<0.05). The gel strength at 60°C increased slightly at 30 min, but then continued to decrease with longer setting times. There was no increase of gel strength at 70°C, but only a continuous decrease over setting time. In conclusion, suwari (gel setting) and modori (gel degradation) phenomena occur during the gel formation of surimi from MDCM. The temperature range in chicken surimi was 47.5 to 52.5°C for suwari and 60 to 70°C for modori. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 12 : 1758-1763)

Microstructure, physicochemical properties and retrogradation behaviour of Mucuna bean ( Mucuna pruriens) starch on heat moisture treatments

Mucuna bean starch was subjected to hydrothermal modifications by heat moisture conditioning at 18% (HMM 18), 21% (HMM 21), 24% (HMM 24) and 27% (HMM 27) moisture levels. At the temperature range studied (60–90 °C), increasing level of moisture conditioning reduced the solubility and swelling capacity. Solubility and swelling were pH dependent, with maximum values obtained at pH 12 in both native and modified starches. Increasing degree of alkalinity increased both solubility and swelling capacity. Water absorption capacity of the starch increased with the severity of moisture treatments, while the oil absorption capacity decreased. Apart from HMM 18, all other modifications improved the gel forming capacity and firmness of the native starch. Pasting temperature increased after hydrothermal modifications, whereas peak viscosity ( P v), hot paste viscosity ( H v), viscosity after 30 min holding at 95 °C ( H v30) and cold paste viscosity ( C v) all reduced after modification. Differential scanning calorimetry studies revealed that heat moisture treatment increased the onset temperature ( T o), peak temperature ( T p) and conclusion temperature ( T c). In addition, gelatinisation band of the native starch increased progressively from HMM 18–HMM 27. Heat moisture treatment reduced the gelatinisation enthalpy (Δ H), while the enthalpy of retrogradation (Δ H r) increased with the storage time of the gelatinised starch. However, Δ H r of the heat moisture conditioned starches were lower than the value obtained for the native starch. Microscopy studies revealed no change in shape and size between the native and modified starches.

Effect of cholecalciferol-enriched hen feed on egg quality.

Eggs are one of the most important sources of vitamin D in the human diet, and their vitamin D content can be further increased by adding more vitamin D to hen feed. To investigate this issue more closely, we performed two feeding experiments. In both, zero egg samples were collected while the hens were fed regular feeds with a vitamin D content of 1720 or 4280 IU/kg. In experiment 1, egg samples were collected 2, 4, 7, 9, 11, 13, 16, 23, and 30 days after beginning the high-cholecalciferol (11 200 IU/kg) feeding period. In experiment 2, samples were collected 2, 4, 6, 8, 13, 28, 56, 84, 112, 140, and 168 days after beginning the high-cholecalciferol (12 000 IU/kg) diet. The egg samples were then assayed for their cholecalciferol content, and some samples, also for the presence of 25-hydroxycholecalciferol by an HPLC method. Further, the vitamin D-fortified eggs were compared with the controls by a sensory evaluation, by conducting fatty acid and functional analyses (emulsion capacity, gel forming capacity, foaming properties) and by measuring eggshell strength. Because vitamin D can be toxic in high doses, we also performed histopathological tests on the hens at the end of experiment 2. The top cholecalciferol contents in egg yolk (ca. 30 microg/100 g) were reached 8-13 days from starting the high-cholecalciferol diet. After 112 days feeding the cholecalciferol content gradually decreased to ca. 22 microg/100 g. When added to eggs as described above, vitamin D did not affect their sensory or functional properties or their fatty acid composition. Moreover, the cholecalciferol levels used in this study appeared not to affect eggshell strength or to be harmful for hens.

1H NMR Investigation of the Composition, Structure, and Dynamics of Cholesterol−Stilbene Tethered Dyad Organogels

The self-assembly of stilbene−cholesterol tethered dyads into fibrous networked structures induces the thermoreversible gelation of several classes of organic solvents. Herein, the gel and solution phases of the gelator, p-α-cholesteryl-p‘-octoxystilbenoate (1), are investigated in 1-butanol-d10 (gel forming) and cyclohexane-d12 (nongel forming) by variable-temperature 1H NMR spectra, T1, and T2 relaxation measurements. All of the NMR data are consistent with detection of 1 in the gel phase by a fast exchange on the NMR time scale between residual 1 dissolved in the gel liquid and 1 in a “mobile” (NMR detectable) gel solid. This conclusion is significant since in previous NMR studies on other gel systems detection of gelator in the gel phase was considered only within “mobile” regions of the gel solid. The decrease in peak integrals of 1 in the gel phase by declining temperatures reflects a convolution of (1) a decrease in concentration of 1 dissolved within the gel liquid as it condenses onto the gel sol...

Chemical and functional properties of sardine (Sardina pilchardus W.) dark and light muscle proteins during frozen storage. Effect of washing on mince quality / Propiedades químicas y funcionales de las proteínas del músculo oscuro y claro de sardina (Sardina pilchardus w.) durante el almacenamiento en congelación. Efecto del lavado en la calidad del músculo picado

This paper examines the effects of eight months of frozen storage on the protein conformation and functionality of whole, light and dark sardine muscles, and washed mince. The variation in protein surface hydrophobicity and Ca-ATPase activity was different in dark muscle from that in whole muscle over the storage period. The dark muscle lacked gel forming capacity because of its higher fat content and a greater presence of low molecular weight proteins, and it also became insoluble faster than the light muscle. The Ca-ATPase activity of the actomyosin extracted from the dark muscle was higher than in light or whole muscle during the first three months. Washing the minced muscle induced conformational changes in the myosin molecule which, together with the added cryoprotectants, contributed to greater functional stability of the washed mince at least during the first three month's storage, at which stage gels were somewhat softer and more elastic than with unwashed mince.

Physicochemical characteristics and antitumor activities of a highly branched fungal (1----3)-beta-D-glucan, OL-2, isolated from Omphalia lapidescens.

Physicochemical properties and antitumor activities of a fungal (1----3)-beta-D-glucan, OL-2, isolated from Leiwan (Omphalia lapidescens) were examined. OL-2 showed sharp signals on carbon-13 nuclear magnetic resonance spectrum in dimethylsulfoxide-d6 as a solvent, and these signals were significantly reduced by the addition of distilled water to the concentration of 20%. This phenomenon is consistent with the general property of the gel forming (1----3)-beta-D-glucan. Binding of OL-2 to Congo red induced a significant change of lambda max to a longer wavelength, and the concentration to induce gel to sol transition was about 0.7 N; in contrast, the concentration was about 0.2 N in the cases of SPG and curdlan. These observations suggested that the gel structure would be significantly stabilized in the case of OL-2. OL-2 showed no or low antitumor activity against the solid form of Sarcoma 180 by intraperitoneal and intralesional administrations; however, it was effective on the ascites form of Sarcoma 180. Of interest, OL-2 also showed significant antitumor activity against the ascites form of MH-134 when administered with 5-fluorouracil. These results indicated that OL-2 showed characteristic features regarding its physicochemical properties and antitumor activity.

Production of proteoglycans by immobilized chondrocytes: Effect of divalent cations

Rabbit articular chondrocytes immobilized in alginate beads maintained normal morphology and metabolic activity (glucose consumption) for more than two weeks whether calcium, barium, or strontium were used for the gel forming. Only Ca- and Ba-alginate immobilized chondrocytes produced proteoglycans in the external medium. Only Ca-alginate beads produced proteoglycans at a constant rate.

Gamma Irradiation Effects on Shelf Life and Gel Forming Properties of Washed Red Hake (Urophycis chuss) Fish Mince

ABSTRACTFresh washed red hake (Urophycis chuss) mince without cryoprotectants was irradiated at 0 (control), 0.66 and 1.31 kGy and stored aerobically at 3.3°C. The total aerobic plate counts of the control and the low and high levels irradiated samples remained less than 106 CFU/ g for 4, 10, and 17 days, respectively. Gel strength decreased after irradiation of mince, and such decreases were dose‐dependent. Irradiation extended sensory shelf life of unfrozen fish mince 12–18 days and microbiologically (&lt;106 CFU/g) 6–13 days longer than the unirradiated control.

Development of Novel Functional Properties by Biological, Chemical and Physical Modification of Food Proteins

With a view to develope novel functional properties of food proteins, biological, chemical and physical modification was carried out. Differences of nucleotide sequence found in cDNA of soybean glycinin A1aB1b subunit prepared from Glycin max var. Shirotsurunoko and Bonminori suggest that oligonucleotide site-directed mutagenesis is useful to develope novel functional properties. Formation of n-hexanal, undesirable flavor, was depressed in soybean by the deletion of lipoxygenase 2. In addition, n-hexanal was proved to be produced enzymatically from 13-hydroperoxy-linoleic acid by hydroperoxidelyase. Soy glycinin and αs1-casein were lipophilized by chemically attaching naturally occurring fatty acids to them. The covalent attachment of fatty acid residues to these proteins caused an increase in their emulsification activity. The binding of orthophosphate to soy proteins increased gel forming and emulsification activities even at acidic environment. Soy proteins and maize protein, zein, were associated with soy lecithin and phosphatidate by sonication, respectively. The emulsiffication activity of phospholipid-protein complex was highly increased after they were treated with 50% alcohol or pro tease digestion.

Kinetics of Gel Forming in Enzyme Coagulated Milk

A semi-empirical kinetic model has been developed to explain the observed kinetics of gel formation in enzyme coagulated milk. The kinetic model assumes that the actual system can be represented by a two-step reaction in series model in which both reactions are first order.The initial reaction is the formation of potential cross-link points corresponding to the hydrolysis of K-casein which covers the surface of casein micelles. The second reaction is the formation of cross-links between casein micelles as individual micelles interact with each other. The initial reaction is dependent on the concentration of enzyme in the solution, while the second reaction is enzyme independent. The formation of increasing numbers of cross-links results in an increase in the shear modulus of the gel. The model correctly predicts the general shape of the shear modulus vs. time curve, and faithfully accounts for the influence of enzyme concentration of the rate of shear modulus increase. It is also consistent with the influence of pH and temperature, and denaturation on the activity of the enzyme for the range of these values tested.

Structural studies on gels from isotactic polystyrene

The thermoreversible gelation phenomena exhibited by isotactic polystyrene (i-PS) was examined in depth, utilising a variety of experimental techniques. The primary aims were identification, relationship, description and visualisation of the morphologies corresponding to the two types of crystallization as diagnosed by the different crystal structures revealed by X-ray diffraction. While centred on electron microscopy the investigation used X-ray and electron diffraction, differential scanning calorimetry and Fourier transform infra-red spectroscopy in combination. A satisfactory correlation between all these techniques was established, including the important reassurance that the characteristics of the gel state are preserved on drying, a feature necessitated by most structure methods. Thei-PS gel system as a whole displays particularly clearly the distinction between gel forming and chain folded lamellar crystallization and the coexistence, morphological relationship and competition between the two crystallizable species. In addition, and most significantly, the gel crystals possess a crystal structure involving extended chains, close to an all-trans conformation, which are quite different to those obtained from conventionally crystallizedi-PS (31 helix). This former extended conformation in itself has become the starting point for new geometric and stereochemical considerations and in addition offers a convenient diffraction based fingerprint to delineate between the two modes of crystallization. Thus the conversion of the gel crystal structure to the conventional 31 helix structure on heating could be monitored. Further, that in the processes of heat annealing, remnants of these gel fibres initiate the development and dictate the orientation of a shish-kebab type platelet growth with the 31 helix crystal structure. This conversion process has been followed by electron microscopy and supplemented infra-red spectroscopy, low angle X-ray diffraction and differential scanning calorimetry. The different roles of fibres and platelets on stretching have been identified. Conditions for the existence of the gel crystals in their different variants are specified with relevance to ongoing arguments and discussions in the subject. Further, it was established that passing through the gel phase significantly enhanced the crystallization in the conventional crystal form making the normally slowly crystallizingi-PS into a fast crystallizable polyolefin.

UTILIZATION OF MINCED SUCKER FLESH

ABSTRACTFreshwater suckers (Catostamidae family) were obtained from Lake Huron to study the possibility of developing new products utilizing its flesh and the influences of additives on the functionality of sucker muscle proteins. Results showed that sodium chloride increased protein solubility, but also decreased swelling, gel forming and pH. In comparison, sodium tripolyphosphate increased protein solubility, pH, swelling and gel formation. Fish sausages and canned products showed low binding characteristics. However, adding corn meal and soy protein in combination with sodium chloride and sodium tripolyphosphate improved their water holding capacity, texture and cook yield. It was concluded that sodium tripolyphosphate, corn meal and fat should be used in manufacturing minced sucker products.

Roasting of Navy Beans (Phaseolus vulgaris) by Particle‐to‐Particle Heat Transfer

ABSTRACTA rotating chamber dry roaster using pre‐heated ceramic beads as heat transfer media was used to roast navy beans. Processing conditions were: beads temperature, 240 and 270°C; bean‐to‐bead ratio, 1/10 and 1/15 and contact times of 1 and 2 min. Product temperatures achieved ranged from 92–125°C for the eight runs. Heat transfer coefficients varied from 3.6–23.4 W/(m2) (°C). Roasted products showed reduced water‐soluble nitrogen content and gel forming capacity, increased water‐holding capacity and cold paste viscosities, and no changes in available lysine and degree of starch damage. Residual trypsin inhibitor (TIA) and hemagglutinin activity varied from 92 to 22%, and 48 to 1%, respectively. A correlation was found to exist between nitrogen solubility index and TIA of products. Roasting caused fracture and separation of hulls, and facilitated their removal.

Effect of initial pH in broiler breast muscles on gel forming capacity of meat proteins and on rheological characteristics of frankfurter‐type sausage

SummaryGel forming capacity (GFC) of proteins extracted from broiler breast muscles of various initial pH values, as well as some technological and rheological characteristics of frankfurter‐type sausages manufactured from normal, PSE‐ and DFD‐type muscles of broilers were investigated.Myofibrillar proteins showed generally a considerably higher GFC than sarcoplasmic proteins. Both proteins isolated from normal muscles (pH15 6.2) demonstrated significantly better GFC than proteins from PSE (pH15 5.7) and DFD (pH15 6.5) type meat.GFC was affected by the pH of the solution in a model system and showed an optimum at pH 6.0 for all three protein fractions.Dynamic viscosity was markedly higher for myofibrillar than for sarcoplasmic proteins. No differences in viscosity were found between myofibrillar and sarcoplasmic proteins as influenced by pH15 in the muscles. Myofibrillar proteins produced a considerably more rigid gel than sarcoplasmic ones, as measured by its linear strain. Protein gels from normal muscles exhibited stronger consistency than those from PSE‐ and DFD‐type muscles. Viscosity of sausage meat was higher in the samples originating from meat of pH15 6.2 in comparison with meat of lower and higher pH15 values.The lowest free water content was found in model sausages produced from normal meat, intermediate in these of PSE‐type meat, and the highest one in the sausages obtained from DFD‐type meat. Such rheological characteristics as linear, plastic, and elastic strains showed the best quality in sausage manufactured from normal meat. It may be concluded that the initial condition of broiler breast muscles affects markedly some technological properties of meat and the quality of the ready‐to‐eat product.

Cryofibrinogen in the plasma of patients with skin ulcerative lesions on the legs: A complex of fibrinogen and cold insoluble globulin

Cryofibrinogen was separated from the plasma of four patients with skin ulcers on the legs. It was identified as a complex of fibrinogen and the cold insoluble globulin based on its sedimentation coefficients, electrophoretic mobilities, thrombin-clottability and amino acid compositions. It formed a solid gel with fibrin strands in a short time at 4°C and readily redissolved at 37°C. The fibrinogen in the fraction was not significantly affected by proteolytic enzymes since its subunits were found to be well retained when examined by SDS polyacrylamide gel electrophoresis. The heat-defibrination at 56°C for 3 min resulted in a loss of gel forming capacity, however, the reconsitution with an equivalent amount of purified human fibrinogen apparently recovered it to a certain extent, but not to the initial level. The sedimentation coefficient of the non-fibrinogen fraction fell between 11 S and 13 S and its estimated molecular weight was 4.4 × 10 5. The amino acid compositions were found to be consistent with those recently reported on the cold insoluble globulin in the normal plasma.

Preparation and &lt;i&gt;In vitro&lt;/i&gt; Evaluation of Theophylline Loaded Gastroretentive Floating Tablets of METHOCEL K4M

This investigation describes the preparation and in vitro evaluation of gastroretentive floating tablets of theophylline. Hydrophilic polymer METHOCEL K4M was used for its gel forming and release controlling properties. Sodium bicarbonate and citric acid were incorporated as gas generating agents. The effects of soluble components (sodium bicarbonate and citric acid), gel forming agent (METHOCEL K4M) and dose variation on drug release profile and floating properties were investigated. It has been observed that in all cases increase of the amount of floating agent caused a decrease of the floating lag time. Increase of theophylline load showed an increase of the floating lag time, which was independent of floating agent content. The release mechanisms were explored and explained with zero order, first order, Higuchi, Korsmeyer and Hixon-Crowell equations. The release rate, extent and mechanisms were found to be governed by the content of polymer and floating agent. The content of active ingredient was also a vital factor in controlling drug release pattern. It was found that polymer content and amount of floating agent significantly affected the time required for 50% of drug release (T50%), percentage drug release after 8 hours, release rate constant, and diffusion exponent (n). Kinetic modeling of dissolution profiles revealed that the drug release mechanism could range from diffusion controlled to case II transport, which was mainly dependent on presence of relative amount of theophylline, polymer and floating agent. Key words: Gastroretention, Floating tablet, Theophylline  DOI = 10.3329/dujps.v7i1.1220 Dhaka Univ. J. Pharm. Sci. 7(1): 65-70, 2008 (June)