DSC study on the influence of meat source, salt and fat levels, and processing parameters on batters pressurisation

 Hydrostatic high-pressure/temperature treatments were conducted at low (10 °C) and high temperatures (60, 70, and 80°C) on different types of meat batters. Pressure-induced effects on proteins were intensified by sodium chloride molarity at low and high temperatures. Treatments at 10°C under pressurisation yielded net thermal destabilisation effects on meat proteins pertaining either to muscle or batter systems. Heating at usual cooking temperature of 70°C under pressure yielded net stabilising effects on meat batter proteins. Overheating at 80°C was needed for entire protein denaturation. Pork and chicken meats were very similar in behaviour but chicken batters exhibited relatively higher thermal- and pressure-induced protein denaturation. Both kinds of physical destabilisation/stabilisation of proteins by pressure-induced effects increased with pressure level. Received: 30 December 1999 / Revised version: 14 February 2000     

A three-prong strategy to develop functional food using protein isolates recovered from chicken processing by-products with isoelectric solubilization/precipitation

BACKGROUND: Skin‐on bone‐in chicken drumsticks were processed with isoelectric solubilization/precipitation to recover muscle proteins. The drumsticks were used as a model for dark chicken meat processing by‐products. The main objective of this study was conversion of dark chicken meat processing by‐products to restructured functional food product. An attempt was made to develop functional food product that would resemble respective product made from boneless skinless chicken breast meat. A three‐prong strategy to address diet‐driven cardiovascular disease (CVD)with a functional food was used in this study. The strategy included addition of three ingredients with well‐documented cardiovascular benefits: (i) ω‐3 polyunsaturated fatty acid‐rich oil (flaxseed‐algae, 9:1); (ii) soluble fiber; and (iii) salt substitute. Titanium dioxide, potato starch, polyphosphate, and transglutaminase were also added. The batters were formulated and cooked resulting in heat‐set gels. RESULTS: Color (L*a*b*), texture (torsion test, Kramer shear test, and texture profile analysis), thermal denaturation (differential scanning calorimetry), and gelation (dynamic rheology) of chicken drumstick gels and chicken breast gels were determined and compared. Chicken drumstick gels generally had comparable color and texture properties to the gels made from chicken breast meat. The endothermic transition (thermal denaturation) of myosin was more pronounced and gelation properties were better for the drumstick gels. CONCLUSION: This study demonstrated a feasibility to develop functional food made of muscle proteins recovered with isoelectric solubilization/precipitation from low‐value dark chicken meat processing by‐products. The functional food developed in this study was enriched with CVD‐beneficial nutrients and had comparable instrumental quality attributes to respective products made of chicken breast meat. Although the results of this study point towards the potential for a novel, marketable functional food product, sensory tests and storage stability study are recommended. Copyright © 2012 Society of Chemical Industry     

Gelation of chicken batters during heating under high pressure

The gelling process of chicken meat batters, which were heated (75 °C) under atmospheric pressure or high pressure (200/400 MPa), was investigated by determining the hardness of batter, residual denaturation enthalpy, microstructure, and protein secondary structure. The results showed that meat batters heated at 200 MPa showed a similar increase in hardness to heat-only samples, but meat batters heated at 400 MPa showed a texture decreasing tendency after a limited increase. High pressure disrupted the myofibrils, promoted protein denaturation and aggregation in the first stage of heating under pressure treatment. In the second stage of treatment, heating was the main driving force for protein gelation, which was disturbed by hindering the structural transformation of proteins in the presence of high pressure during heating. The effect of 200 MPa on muscle proteins was relatively gentle and had a less negative effect. Excessive high pressure should be avoided when applying heating under pressure for gel-type meat products processing.Industry relevanceHigh-pressure processing is increasingly applied in the meat industry. By combining high pressure with heating, their effects on texture improvement and microbial inactivation can be maximized. In this study, the influence of high pressure on the texture of meat products was analyzed, which showed that excessive pressure would significantly interfere with the thermal denaturation of the protein, thus adversely affecting the formation of the gel structure. High pressure at 400 MPa and above should be avoided when applying heating under pressure for gel-type meat products processing.     

Rheological changes during thermal processing of low-fat meat emulsions formulated with different texture-modifying ingredients

The rheological behaviour of high-fat (22%) and low-fat (8%) meat emulsions during thermal processing in the presence (3%) of various texture-modifying non-meat ingredients, namely maltodextrin, starch, wheat flour, egg white and apple fibre, was analysed. Rheological properties of emulsions were assessed using non-destructive measurements (thermal scanning rigidity monitor, TSRM). The lower the fat content, the lower were the rigidity values of meat emulsions throughout the temperature range studied. Emulsions made with maltodextrin proved less rigid. Addition of starch and egg white favoured the formation of more rigid structures in low-fat meat emulsions at temperatures over 55 °C. Low-fat meat batters containing wheat flour and apple fibre exhibited the highest rigidity values over the given temperature range. The presence of wheat flour caused variations in the modulus of rigidity at all stages of the thermal gelation process, very similar to those observed in high-fat emulsions.     

Application of high‐pressure treatment in the mashing of white malt in the elaboration process of beer

In this study, high‐pressure treatment (HPT) was applied to the mashing stage of beer production, which involves drying and milling of white malt and subsequent mixing with water. The following parameters were evaluated after pressurisation: β‐glucanase activity, starch gelatinisation and sugar extraction. Evaluation of starch hydrolysis from the malted barley endosperm after HPT was performed by measuring β‐glucanase activity after pressurisation; this enzyme breaks down gums and β‐glucans in wort and is desirable to obtain a good‐quality beer. Soaked malt samples pressurised at 200–600 MPa showed no increase in this activity compared with controls. Conversion of milled malt was evaluated indirectly by measuring the gelatinisation of starch, which began at 400 MPa. Soluble sugars were also measured in pressurised samples from the mashed liquid to investigate saccharification during the mashing stage. After 400 or 600 MPa treatment for 20 min, both the sucrose (g per 100 ml) and extract (l ° kg^?1) values were the same as those found in mashed samples following the standard procedure used in the brewing industry (65 °C,90 min). Starch gelatinisation was analysed at different high pressures (200–600 MPa) and it was shown that gelatinisation began at 400 MPa. The HPT time would have to be shorter to make the process commercially attractive. © 2002 Society of Chemical Industry     

A study of the baking process by differential scanning calorimetry

The denaturation of the components of a baked product such as cake or bread can be observed under simulated baking conditions by differential scanning calorimetry. When starch or protein denaturation occurs, an increased flow of heat shows the temperature range over which that process takes place. Experimental results are presented for angel cake. In the absence of sucrose, the egg-white proteins are denatured predominantly near 65 and 85°C. For wheat flour, starch denaturation is observed near 65°C, and protein denaturation over a broad range from 80 to 110°C. In the presence of the concentration of sucrose used in a standard batter, both the starch and the major portion of the egg-white proteins are denatured near 95°C, at approximately the maximum temperature attained by the cake when it reaches maximum volume in the oven. Apparently, the main function of sucrose in an angel cake is to raise the denaturation temperature ranges of the starch and protein. Decreasing the amount of sucrose in batters designed for high altitudes causes denaturation of starch and protein at the lower maximum temperatures attained at those altitudes. This assures formation of a structural framework of denatured starch and protein which will not allow the cake to “fall” after it attains its maximum volume.     

Contribution of High‐Pressure‐Induced Protein Modifications to the Microenvironment and Functional Properties of Rabbit Meat Sausages

Rabbit meat batters were subjected to high pressure (HP, 100 to 300 MPa for 3, 9, or 15 min) to elucidate their effects on proteins structures, the microenvironment, and the resulting functionalities of the subsequently heated products. To determine these effects, we investigated structural and microenvironmental changes using Raman spectroscopy and also expressible moisture content, textural characteristics, and dynamic rheological properties of batters during heating (20 to 80 °C). Untreated samples served as controls. Analysis of specific Raman spectral regions demonstrated that applications of HP to rabbit meat batters tended to induce the transformation of the all‐gauche S‐S conformation to gauche‐gauche‐trans in the batter system. HP treatment higher than 100 MPa for 9 min promoted secondary structural rearrangements, and molecular polarity enhancement in the proteins prior to cooking. Also, increases of O–H stretching intensities of rabbit meat sausages were obtained by HP treatment, denoting the strengthening of water‐holding capacity. These HP‐induced alterations resulted in improved texture and, perhaps, improved juiciness of rabbit meat sausages (P < 0.05), however they had relatively poorer rheological properties than the controls. Nevertheless, HP treatment, especially 200 MPa for 9 or 15 min, was an effective technique for improving the functionalities of gel‐type products through modification of meat proteins.     

Rheological,thermal and microstructural properties of whey protein isolate‐modified cassava starch mixed gels at different pH values

The objective of this study was to investigate the rheological, thermal and microstructural properties of whey protein isolate (WPI)‐hydroxypropylated cassava starch (HPCS) gels and WPI‐cross‐linked cassava starch (CLCS) gels at different pH values (5.75, 7.00 and 9.00). The rheological results showed that the WPI‐modified starch gels had greater storage modulus (G?) values than the WPI‐native cassava starch gels at pH 5.75 and 7.00. Differential scanning calorimetry curves suggested that the phase transition order of the WPI and modified starch changed as the pH increased. Scanning electron microscopy images showed that the addition of HPCS and CLCS contributed to the formation of a compact microstructure at pH 5.75 and 7.00. A comprehensive analysis showed that the gelling properties of the WPI‐modified starch were affected by the difference between the WPI denaturation temperature and modified starch gelatinisation temperature and by the granular properties of the modified starch during gelatinisation. These results may contribute to the application of WPI‐modified starch mixtures in food preparation.     

Analysis of the effects of thermal protein denaturation on the quality attributes of sous‐vide cooked tuna

Traditional (low temperature, long time) and novel (low temperature, short time) sous‐vide cooking of lean tuna were characterized by analyzing the effects of thermal protein denaturation (TPD) on quality attributes, such as color, appearance, shrinkage, drip loss, and texture. TPD was analyzed by differential scanning calorimetry and estimated for several thermal schedules by kinetic analysis, following the dynamic method. When heated at a rate of 10 °C/min, myosin began to denature at around 35 °C. Actin did not denature, even when the temperature rose to approximately 51 °C, until the denaturation of myosin was complete. However, actin began to denature at approximately 58 °C and was completely denatured at 76 °C. Actin denaturation had a stronger effect than myosin denaturation on texture changes, whereas myosin denaturation was responsible for changes in color and appearance. A better preservation of tuna quality was obtained by novel sous‐vide cooking over the traditional sous‐vide method.

Practical applications

The results of this study are useful to both the research community and industry because they provide quantitative characterization of the consequences of sous‐vide cooking method on food quality explained by estimating TPD. Moreover, the kinetic parameters of the denaturation rate collected for kinetic modeling of the TPD of tuna, not only have application to simulate denaturation of actin and myosin under different thermal schedules of sous‐vide cooking, but also they can be used for the analysis of additional thermal treatments.     

GELATION KINETICS of MEAT EMULSIONS CONTAINING VARIOUS FILLERS DURING COOKING

A cylindrical shaped thermal scanning rigidity monitor (TSRM) was developed to determine shear rigidity modulus of meat batters during cooking. A meat fatprotein ratio of 1.8, moisture content of 62% and 8.6% filler were used. the fillers were buttermilk powder, corn starch, micro-crystalline cellulose, modified corn starch, modified wheat flour, soy-protein concentrate and whey-protein concentrate. Plots of rigidity modulus versus product-temperature showed two major thermal transitions. the first and most important transition (53 to 61°C) was due to myosin gelation. the second transition (64 to 69°C) was ascribed to the collagen softening. the maximum rigidity-temperature slopes of 0.60 to 1.02 kPa/°C occurred after the first transition.     

High-pressure-cooked Low-fat Pork and Chicken Batters as Affected by Salt Levels and Cooking Temperature

The application of high pressure (200 and 400 MPa, 30 min) favored water and fat binding properties of chicken and pork batters even at low ionic strength. Textural properties of meat batters (particularly hardness and chewiness, and to a lesser extent springiness and cohesiveness) were influenced by cooking temperature. High pressures influenced the texture of batters, so that pressurized samples were less hard, cohesive, springy or chewy than nonpressurized samples; this effect was not related to on salt concentration. High pressure treatment limited the formation of gel structures, which probably was associated with its preserving effect against thermal denaturation of meat proteins.     

Effects of high pressure and temperature on buckwheat starch characteristics

Pressure-induced gelatinisation of buckwheat starch suspensions (25% w/w) was studied and compared to heat-induced gelatinisation. Starch suspensions were treated at increased pressure (200–600 MPa) or temperature (60–95 °C) for 10 min. The degree of gelatinisation and the temperature and pressure ranges of gelatinisation were determined using differential scanning calorimetry, changes in birefringence and pasting behaviour. Furthermore, the structural changes during gelatinisation were investigated using microscopy. The pressure-induced as well as the temperature-induced gelatinisation curves were sigmoid shaped. Gelatinisation occurred between 300 and 500 MPa or between 60 and 70 °C. Scanning electron microscopy images showed retention of the granular structure after treatment with 600 MPa. However, when heated at temperatures above 65 °C, the formation of a “sponge-like” structure was observed. Better preservation of the granular structure for pressure treatment compared to temperature treatment resulted in stronger gels for the former. Pre-treatment with pressure as well as temperature made the buckwheat starch granules more resistant to swelling and disintegration under the influence of additional heat.     

Application of aged egg in enabling increased substitution of sucrose by litesse (polydextrose) in high-ratio cakes

Previous reports show that replacing sucrose by polydextrose in cakes leads to an elevation of the starch gelatinisation temperature such that it no longer coincides with the egg protein denaturation transition. It is known that as eggs age, the ovalbumin transforms to S-ovalbumin with a higher denaturation temperature. Linking these observations led to the hypothesis that baking reduced-sugar cakes with aged eggs might bring the starch gelatinisation into proximity of the protein denaturation thereby improving the final texture. Baking trials and instrumental texture evaluations of the resulting high-ratio cakes were carried out with fresh egg and egg that had been aged at 37°C for 3, 7 and 14 days. Texture changes that do exist are principally related to differences in the cake crumb density and crumb springiness.     

High pressure/thermal treatment of meat batters prepared from freeze-thawed pork

Various meat batters were prepared from pork subjected to different freeze–thaw cycles. These batters were pressurized (300 MPa, 30 min) at low, non-denaturing temperature (10°C) followed by heating (70°C) (PLT+H) and at high, denaturing temperature (70°C) (HUPC). Nonpressurized (NP), heated-only (70°C) sample were also produced. Freezing of meat influenced water binding and textural properties of meat batters; the influence on texture was affected by thermal and pressure conditions. Pressure prior to heating produced a coarse, irregular and loose protein matrix, favoring the formation of weaker gel structures than were found in non-pressurized samples. Pressurization at denaturing temperatures reduced the level of protein denaturation induced by the thermal treatment. The resulting gel structures had better water binding properties but were weaker than non-pressurized samples and samples pressurized prior to heating.     

Influence of acid hydrolysis on thermal and rheological properties of amaranth starches varying in amylose content

BACKGROUND: The granules of amaranth starch are very small compared with starches from other sources. In the current work, amaranth starches with different amylose contents were treated with hydrochloric acid as a function of time in order to study the effect of acid treatments on starches. Differential scanning calorimetry and dynamic oscillation in shear were employed to analyse the thermal and rheological properties of acid‐modified amaranth starch. RESULTS: Results showed that gelatinisation temperatures and enthalpy change of gelatinisation (ΔH) decreased steeply initially, and had a slight increase with further treatment up to 12 h then decreased, an outcome that reflected distinct resistance to acid with various amylose contents. Rheological parameters of storage and loss moduli during heating, cooling and frequency sweep of modified starches reflected the differential scanning calorimetry results by decreasing in value as the time of acid hydrolysis increased. CONCLUSION: With amylose content increase, the effects of acid hydrolysis on gelatinisation temperatures became less pronounced. Nevertheless, prolonged acid hydrolysis decreased the storage and loss moduli, with the starch pastes becoming more liquid‐like. Copyright © 2012 Society of Chemical Industry     

Promoting structure formation by high pressure in gluten-free flours

In order to evaluate the potential of high pressure (HP) treatment to improve the functional properties of gluten-free flours, the effect of HP on the rheological properties of three gluten-free batters was investigated. Buckwheat, white rice and teff batters (40 g/100 g) were treated for 10 min at 200, 400 or 600 MPa. Changes in the microstructure of the batters after HP-treatment were observed using scanning electron microscopy. Pasting profiles revealed HP-induced starch gelatinisation. Furthermore, Lab-on-a-Chip capillary gel electrophoresis revealed protein polymerisation by thiol/disulphide-interchange reactions in white rice and teff batters. For buckwheat proteins however, no such cross-linking mechanism was observed, which was explained by the absence of free sulfhydryl groups. An increase in viscoelastic properties at higher pressures was observed, and could be explained by the modifications occurring in starch and protein structure. Overall, this study has shown that HP-treatment has the potential to improve functional properties of gluten-free batters.     

Effects of high pressure processing on protein fractions of blue crab (Callinectes sapidus) meat

The studies about the effect of high pressure processing (HPP) on the myofibrillar proteins of crab meat are scarce in the literature. The aim of this study is to evaluate the effect of high pressure processing (HPP) at 100, 300 and 600 MPa (10 °C/5 min) on the muscular protein fractions of blue crab meat (Callinectes sapidus) and compares the effect of high pressure treatments and the thermal cooking process on the yielding of crab meat. Differential scanning calorimetry analysis of raw crab meat showed two peaks at 48.18 and 76.76 °C corresponding to myosin and actin denaturation. The increasing in the pressure level resulted in a decrease in denaturation enthalpy of both proteins. Data from Fourier transform infrared spectroscopy indicated changes in the secondary protein structures in which a reduction in α-helix and an increase in β-turn were observed as a result of denaturation induced by HPP. Electrophoresis analysis (SDS-PAGE) showed myofibrillar protein denaturation as the pressure level increased. The HPP at 100 and 300 MPa resulted in a significant increase in the yielding of meat extracted when compared to the thermal treatment (90 °C/20 min). Higher sensory scores were obtained in 300 and 600 MPa suggesting higher acceptance. Results suggest the feasibility of applying HPP as an alternative to the thermal treatment to process crab meat.Industrial relevanceHigh pressure processing (HPP) technology has been successfully applied to several seafood products. However, it is important to study the effect of HPP on the food components, mainly proteins in the crab meat to optimize the processing parameters to get high-quality products. In the present study, the benefit of using HPP as an alternative to the commercial thermal processing for extraction of crab meat has been confirmed. Applying 600 MPa (10 °C/5 min) to the whole blue crab resulted in a higher yield of extracted crab meat compared with the other treatments. However, using a range of 100–300 MPa (10 °C/5 min) also increases the yielding of extracted crab meat when compared to the thermal process, and moreover, the extraction procedure is faster. The quality and the functional properties of the crab meat with fresh appearance is preserved after the treatment at 100 MPa. These results could promote subsequent applications of pressurized crab meat in the crab industry, especially with the HPP treatments in a range between 100 and 300 MPa.     

Effect of storage of adzuki bean (Vigna angularis) on starch and protein properties

Differential scanning calorimetry was used to evaluate the effect of storage at 10°C, 20°C and 30°C, and 40% and 65% relative humidity (RH) on adzuki bean starch gelatinisation and protein denaturation temperatures. Storage for 6 months at an elevated storage temperature (30°C) caused increases in the starch gelatinisation onset temperature (T_o) and gelatinisation peak temperature (T_p) for both Bloodwood and Erimo varieties. Storage at 40% RH resulted in higher T_o and T_p values than storage at 65% RH. The T_o of starch from Bloodwood and Erimo beans stored for up to 1.5 months at 10°C and 65% were similar to those of fresh beans.The changes in the salt-soluble protein component were less clear cut than those of the starch. Nonetheless, protein extracted from beans stored at 40% RH exhibited significantly lower T_o and T_p values compared with those stored at 65% RH. This indicates some destabilisation of the protein at the higher RH.These results suggest that detrimental changes occur in starch and, to a lesser extent protein, of adzuki beans stored under unfavourable conditions. On the basis of these results, the best storage conditions to maintain the characteristics of fresh beans are low temperatures (e.g. 10°C) and high RH (e.g. 65%).     

Apple pomace in gluten‐free formulations: effect on rheology and product quality

The objective of the present work was to formulate a gluten‐free (GF) baked product based on a cassava starch, rice flour and egg white mixture and enriched with apple pomace with minimum processing as source of fibre. Effects of apple pomace and water amount on batters and product quality were analysed by response surface methodology (RSM). Dynamic moduli of batters, specific volume and crumb texture were highly dependent on both apple pomace and water. Higher levels of fibre rendered less cohesive and less resilient crumbs and diminished specific volumes. A suitable balance between amounts of apple pomace and water led to products with enough specific volume and sponginess. Up to 12.5 g apple pomace and water ranging from 115 to 150 g (each 100 g mixture), specific volumes were maintained higher than 2 cm³ g^?1; if apple pomace was increased up to 20 g, water amounts higher than 140 g were necessary to obtain similar results.     

Effects of Growth Temperature on Some Structural Properties of Crystalline Lamellae in Starches Extracted from Sweet Potatoes (Sunnyred and Ayamurasaki)

Thermodynamic characteristics defining gelatinisation (modelled as ‘melting’) processes for starches extracted from two sweet potato cultivars (Ayamurasaki and Sunnyred) grown in soil at different temperatures (15, 21, 27 or 33 °C) were studied using high sensitivity differential scanning calorimetry (DSC). The gelatinisation temperatures for all starches were elevated significantly with increasing growth temperature. A linear correlation between growth temperature and gelatinisation temperature of extracted starches was found for both cultivars. The increase of gelatinisation temperatures was associated with almost constant or slightly increased enthalpy (Ayamurasaki) but with moderate elevation of crystalline lamellae thickness (Sunnyred). Elevation of gelatinisation temperatures by 8‐9 °C by DSC for starches heated in 1.5 M aqueous KCl were found in comparison with aqueous starch dispersions. The crystalline polymorphic form was confirmed as A‐type using wide angle X‐ray scattering (WAXS). The values of the thermodynamic surface parameters characterising the faces of crystalline lamellae of these starches were calculated. Two endothermic peaks were observed by DSC for starches grown at 15 °C when suspended in 1.5 M KCl solution. The first peak was ascribed to the melting of B‐type structure while the second one was attributed to the melting of A‐type structure. As a conclusion it was suggested that these starches contain C‐type polymorphic structures.