Water-holding Capacity Measurements Research Articles

Water Holding Capacity of Some Bryophyta Species from Tundra and North Taiga of the West Siberia

Functional traits are a set of characteristics that are expressed in the phenotype of an individual organism as a response to the environment and their impact on the ecosystem’s properties. They are positioned at the crossroads between the response and influence of the organisms, creating a certain interest in functional ecological and evolutionary fields. Due to this unique position, they are divided into two categories: effect functional traits and response functional traits. Effect traits describe the influence of the species on the environment regardless of whether such traits are an adaptive advantage to the individual or not. In Bryophyta, one of the most important effect traits is water holding capacity (WHC), which is their means of regulating ecosystem hydrology. On a global scale, mosses’ WHC is manifested in the slowdown of the large water cycle, in the storage of huge volumes of fresh water by peatlands and in the enormous paludification of Western Siberia. The main goal of our research was to obtain the water holding capacity measurements of tundra and taiga moss species to establish the base and foundation for environmental monitoring in the north of Siberia—the region with the most rapidly changing climate. Both the capacity to hold water within the moss tissues (WHC) and the capacity to hold water externally between the morphological structures (leaves, branches, rhizoids, etc.) (WHCe) were measured. In total, 95 samples of 9 Sphagnum and 5 true mosses species were involved to the research; some species were collected at two or three sampling sites within two natural zones/subzones that gave us the opportunity to compare the WHC along the meridional transection. In average, the northern taiga samples showed slightly higher WHC than tundra samples, probably due to the environmental specifics of the habitat—the taiga habitats were more moist, while the tundra was drier. Overall, in the majority of species, the standard deviation calculation revealed that the variability of WHCe is significantly higher than that of WHC. Such high variability in WHCe may be explained in regard to the morphological features of each individual considerably shifting between the samples of the same species while the anatomical features retain more stable results.

Measurement of water-holding capacity in fermented milk using near-infrared spectroscopy combined with chemometric methods.

We investigated the use of near-infrared spectroscopy (NIR) for measuring water-holding capacity (WHC) in fermented milk. Increased WHC ensures improved texture and decreased syneresis in fermented dairy products and also improves cheese yield. NIR combined with partial least-squares-discriminant analysis (PLS-DA) was found to be a promising rapid and non-invasive method with no pretreatment of the samples for prediction of WHC in fermented milk samples. Analysis of the chemical bonds in the region 10 700-4500 cm-1 (935-2200 nm) of the electromagnetic spectrum was able to distinguish between samples with high vs. low WHC. This technique was successfully used to screen different strains of lactic acid bacteria for their ability to provide fermented milk with increased WHC, which is of great importance for use in various dairy products.

Physiochemical properties of jet-cooked amaranth and improved rheological properties by processed oat bran

The development of innovative gluten-free amaranth and oat bran mixtures using thermomechanical processing is important for producing products for consumers allergic to wheat proteins. This study intended to develop nutritious food ingredients using steam jet-cooked amaranth flour composted with 10-50% jet-cooked oat bran. The protein, ash, and amino acid contents of amaranth and oat bran flour were investigated along with measurements of water-holding capacity (WHC) and rheological properties. Results showed that amaranth and oat bran have higher protein and ash contents compared to wheat flour. The jet-cooked amaranth flour had decreased particle size and bulk density, whereas the jet-cooking process increased WHC and soluble solids, as well as improved viscoelasticity in comparison with untreated amaranth flour. The protein, ash, and amino acid contents were not influenced by jet-cooking process. Significant positive correlations were found between ash and protein, and between WHC, water absorption index (WAI) and swelling point (SP), respectively. In contrast, significant negative correlation was observed between both protein and ash with bulk density (p < 0.01). Results indicated that the hydro-thermal process and additional processed oat bran greatly enhanced WHC and viscoelastic property that are critical for mixing, cooking, and food applications such as smoothies and porridge products.

Stand-Level Variation Drives Canopy Water Storage by Non-vascular Epiphytes Across a Temperate-Boreal Ecotone

Epiphytes, including bryophytes and lichens, can significantly change the water interception and storage capacities of forest canopies. However, despite some understanding of this role, empirical evaluations of canopy and bole community water storage capacity by epiphytes are still quite limited. Epiphyte communities are shaped by both microclimate and host plant identity, and so the canopy and bole community storage capacity might also be expected to vary across similar spatial scales. We estimated canopy and bole community cover and biomass of bryophytes and lichens from ground-based surveys across a temperate-boreal ecotone in continental North America (Minnesota). Multiple forest types were studied at each site, to separate stand level and latitudinal effects. Biomass was converted into potential canopy and bole community storage on the basis of water-holding capacity measurements of dominant taxa. Bole biomass and potential water storage was a much larger contributor than outer canopy. Biomass and water storage capacity varied greatly, ranging from 9 to &amp;gt;900kg ha–1 and 0.003 to 0.38 mm, respectively. These values are lower than most reported results for temperate forests, which have emphasized coastal and old-growth forests. Variation was greatest within sites and appeared to reflect the strong effects of host tree identity on epiphyte communities, with conifer-dominated plots hosting more lichen-dominated epiphyte communities with lower potential water storage capacity. These results point to the challenges of estimating and incorporating epiphyte contributions to canopy hydrology from stand metrics. Further work is also needed to improve estimates of canopy epiphytes, including crustose lichens.

Muscle water properties in raw intact broiler breast fillets with the woody breast condition

The purpose of this study was to investigate the relationships between muscle water properties, water-holding capacity (WHC), and woody breast (WB) severity in intact raw broiler breast fillets. Broiler pectoralis major deboned at 3 h postmortem was collected from a commercial plant and categorized as normal (NORM), moderate WB, or severe WB (SEV). Meat drip loss was calculated based on weight loss during overnight storage at 4°C. Water properties of the intact fillets were determined with time domain nuclear magnetic resonance and the T2 relaxation times were determined using an inverse Laplace algorithm (CONTIN). Three T2 water components, hydration water (T2b), intra-myofibrillar water (T21), and extra-myofibrillar water (T22), were identified. With increasing WB severity, the time constant of each water component and the relative content of T22 (P22) increased while the relative areas of T2b and T21 (P2b and P21, respectively) decreased. Spearman correlation analysis showed that there were significant correlations between the WB condition score and either the time constant or normalized area for each T2 component. T22 normalized areas (A22) were most strongly correlated with the WB score (r = 0.75); however, the weakest correlation was found between the WB score and T21 areas (A21). Pearson correlation analysis revealed that the strongest correlation (r = 0.64) was found between A22 and drip loss; however, there was no correlation between A21 and drip loss. Within the NORM group, drip loss was significantly correlated to the time constants for both T2b and T21. Within the SEV group, only A22 was significantly correlated to drip loss. These data indicate that the WB condition has a significant impact on the distribution of water within the intact muscle tissue. The content of extra-myofibrillar water in broiler breast fillets may be a key factor responsible for the poor WHC measurements in WB meat.

Laboratory Tests of Substrate Physical Properties May Not Represent the Retention Capacity of Green Roof Substrates In Situ

Green roofs can be used to reduce the volume of polluted stormwater that is generated by cities. Modelling rainfall retention is critical, but green roof water balance models often rely on the physical properties of substrates. In these models, substrate water holding capacity (WHC) determines the depth of water which can be stored before runoff is generated; whereas, the permanent wilting point (PWP) limits evapotranspiration. The WHC and PWP, as well as plant available water (PAW; where PAW = WHC − PWP), as determined from laboratory tests, may not truly reflect how substrates perform on green roofs. We therefore ran a simulated rainfall experiment on green roof modules to (i) compare the rainfall retention of vegetated and non-vegetated substrates with different WHC and PAW, and (ii) relate retention to substrate storage capacity, as calculated from laboratory measures of WHC and PAW. We found that the PAW of a substrate is a better indicator of evapotranspiration and retention when compared with WHC. However, we also found that substrates always retained less water than their calculated storage capacity would suggest, most likely being due to their high permeability. Our results indicate that using laboratory-derived measures of WHC and PAW in green roof models may be over-estimating both evapotranspiration and rainfall retention.

Assessment of objective measures of beef steak juiciness and their relationships to sensory panel juiciness ratings.

The objective of this study was to evaluate multiple instrumental measures of beef juiciness and determine their relationships with sensory panel juiciness ratings. Treatments were selected to maximize variation in juiciness and included 5 USDA quality grades (Prime, upper two-thirds Choice, lower one-third Choice, Select, and Standard) as well as 2 enhanced Select treatments (112 and 107% of the initial raw weight) and were prepared to 3 degrees of doneness (DOD; rare [66°C], medium [71°C], and well done [77°C]). A total of 21 objective measures of raw samples were evaluated and included marbling level, CIE color values, pH, water activity, proximate composition, and multiple measures of water-holding capacity. Also, 17 objective measures were evaluated for cooked beef samples and included cooking loss, drip loss, and compression-based methods used to quantify expressible moisture. These measures were compared with results from a previous sensory study to evaluate the relationship between the various objective measures and sensory panel juiciness ratings. Differences ( < 0.05) were found among quality treatments for many of the measures evaluated, with the greatest differences occurring for many of the measures among samples cooked to different DOD. Of all the objective measures evaluated, protein percentage, cooking loss, and pressed juice percentage (PJP) were most closely associated ( < 0.05) with consumer juiciness ratings ( = -0.55, = -0.51, and = 0.45, respectively). Additionally, cooking loss and PJP were more closely associated ( < 0.05) with trained sensory panel initial and sustained juiciness ratings than all other measures evaluated. Regression analysis revealed that PJP explained ( < 0.05) 20, 48, and 45% of the variation in consumer, trained panel initial, and trained panel sustained juiciness scores, respectively. This was a greater percentage of the variation than slice shear force explained ( < 0.05) in trained sensory panel initial (39%) and sustained tenderness ratings (40%) and similar to the amount explained (26%) in consumer tenderness ratings. These results indicate PJP was a better predictor of sensory panel juiciness scores than all traits evaluated other than the cooking loss of steaks evaluated by sensory panelists. Pressed juice percentage explained a similar or greater amount of variation in sensory panel scores as slice shear force, indicating PJP as a potential industry standard for objective juiciness evaluation.

Comparison of Muscle Fiber and Meat Quality Characteristics in Different Japanese Quail Lines.

The aim of this study was to compare the growth performance, fiber characteristics of the pectoralis major muscle, and meat quality characteristics in the heavy weight (HW) and random bred control (RBC) quail lines and genders. The HW male exhibited more than two times greater body (245.7 vs 96.1 g, p<0.05) and pectoralis major muscle (PMW; 37.1 vs 11.1 g, p<0.05) weights compared to the RBC female. This growth performance in the HW line was associated with a greater muscle fiber area (1,502 vs 663.0 μm2, p<0.001) compared to the RBC line. Greater muscle mass of the HW male was accompanied by a higher percentage of type IIB fiber compared to the HW female (64.0% vs 51.0%, p<0.05). However, muscle fiber hyperplasia (increase in fiber number) has had a somewhat limited effect on PMW between the two lines. On the other hand, the HW line harboring a higher proportion of type IIB fiber showed rapid pH decline at the early postmortem period (6.23 vs 6.41, p<0.05) and lighter meat surface (53.5 vs 47.3, p<0.05) compared to the RBC line harboring a lower proportion of type IIB fiber. There were no significant differences observed in the measurement of water-holding capacity including drip loss (2.74% vs 3.07%, p>0.05) and cooking loss (21.9% vs 20.4%, p>0.05) between the HW and RBC lines. Therefore, the HW quail line developed by selection from the RBC quail, was slightly different in the meat quality characteristics compared to the RBC line, and a marked difference was found in growth performance between the two quail lines.

Evaluating nuclear magnetic resonance (NMR) as a robust reference method for online spectroscopic measurement of water holding capacity (WHC)

The potential of using NMR as a reference method for WHC measurement in porcine longissimus dorsi was investigated. The accuracy of NMR when measuring small water changes was assessed in a model system and in muscles. Visible/near infrared (Vis/NIR) and X-ray were used as potential online spectroscopic methods to assess WHC on 40 muscles. Drip loss and spin–spin relaxation were also measured. Calibration models were built using partial least squares regression (PLSR) with Vis/NIR or X-ray spectra as input and NMR or drip loss values as output. The slowest spin–spin relaxation time (T22) showed higher correlation with both Vis/NIR (RCV2 = 0.66) and X-ray spectra (RCV2 = 0.76) than EZ-DripLoss values, demonstrating NMR has potential as a reference method for WHC measurement. NMR was more robust against variation along the length of the muscle when compared to the EZ-DripLoss method.

Automated static image analysis as a novel tool in describing the physical properties of dietary fiber

The growing interest in the usage of dietary fiber in food has caused the need to provide precise tools for describing its physical properties. This research examined two dietary fibers from oats and beets, respectively, in variable particle sizes. The application of automated static image analysis for describing the hydration properties and particle size distribution of dietary fiber was analyzed. Conventional tests for water holding capacity (WHC) were conducted. The particles were measured at two points: dry and after water soaking. The most significant water holding capacity (7.00 g water/g solid) was achieved by the smaller sized oat fiber. Conversely, the water holding capacity was highest (4.20 g water/g solid) in larger sized beet fiber. There was evidence for water absorption increasing with a decrease in particle size in regards to the same fiber source. Very strong correlations were drawn between particle shape parameters, such as fiber length, straightness, width and hydration properties measured conventionally. The regression analysis provided the opportunity to estimate whether the automated static image analysis method could be an efficient tool in describing the hydration properties of dietary fiber. The application of the method was validated using mathematical model which was verified in comparison to conventional WHC measurement results.

The Effect of Sex on the Dressing Percentage, Carcass, and Organ Quality in the Fallow Deer (Dama Dama)

Abstract Basic carcass characteristics, the quality traits of meat and internal organs from 10 fallow deer bucks and 10 does aged from 31 to 32 months were investigated. No sex effects on the bled body weight, meat yield and carcass composition were found. A significantly higher weight of mesenteric and omental fat (by 0.44 kg) was found for does. The combined share of muscle and fat in the carcass parts ranged from 77.9 to 78.5%, and the share of bones from 21.5 to 22.1%. No sex effects were found for the pH and water holding capacity measurements. Venison from males was characterized by a significantly higher thermal drip value (P=0.043) and higher L* (P=0.026), a* (P=0.010) and b* (P=0.036) values compared to does. The extracted fat content was significantly higher for females compared to males (P=0.009). The chemical analysis of deer edible by-products indicated the highest level of protein for the liver (17%), and the highest level of dry matter and fat for the tongue (33-34% and 15-18%, respectively).

Relationship between water-holding capacity and protein denaturation in broiler breast meat

The objective of this study was to determine the relationship between water-holding capacity (WHC) attributes and protein denaturation in broiler breast meat. Boneless skinless breast fillets (n = 72) were collected from a commercial processing plant at 2 h postmortem and segregated into low-WHC and high-WHC groups based on muscle pH and color (L*a*b*). At 6 and 24 h postmortem, brine uptake (%), cooking loss (%), and protein solubility (sarcoplasmic and myofibrillar) were measured and protein fractions were analyzed using SDS-PAGE. Drip loss accumulation (%) was measured after storage for 2 and 7 days postmortem. High-WHC fillets exhibited lower L*-lightness values and greater pH values at 2 and 24 h postmortem than low-WHC fillets. High-WHC fillets had greater brine uptake and less cooking loss at both 6 and 24 h postmortem compared to low-WHC fillets. Aging from 6 to 24 h postmortem increased brine uptake in high-WHC fillets, but did not affect cooking loss in either low-WHC or high-WHC fillets. Drip loss accumulation was greater in low-WHC fillets at both 2 and 7 days postmortem. Myofibrillar protein solubility decreased with postmortem time but was not different between low-WHC and high-WHC fillets. Sarcoplasmic protein solubility increased with postmortem time and was greater in high-WHC fillets. SDS-PAGE analysis indicated that low-WHC fillets exhibited more glycogen phosphorylase denaturation than high-WHC fillets as evidenced by a more extensive shift of the protein from the sarcoplasmic to the myofibrillar protein fraction. Correlation analysis revealed that overall protein solubility measurements were not related to WHC attributes but that the degree of glycogen phosphorylase denaturation was significantly correlated (|r| = 0.52 to 0.80) to measures of WHC. Data indicated that WHC differences in broiler breast fillets were not due to differences in myofibrillar protein denaturation and suggested that the denaturation of sarcoplasmic proteins onto myofibrils may influence WHC in breast meat.

Measurement of water-holding capacity in raw and freeze-dried broiler breast meat with visible and near-infrared spectroscopy

The feasibility of using visible/near-infrared spectroscopy (vis/NIR) to segregate broiler breast fillets by water-holding capacity (WHC) was determined. Broiler breast fillets (n = 72) were selected from a commercial deboning line based on visual color assessment. Meat color (L*a*b*), pH (2 and 24 h), drip loss, and salt-induced water uptake were measured. Reflectance measurements were recorded from 400 to 2,500 nm in both raw and freeze-dried breast meat samples. Raw and freeze-dried samples had similar spectra in the visible region (400–750 nm), but the freeze-dried samples exhibited numerous bands in the NIR region (750–2,500 nm) corresponding to muscle proteins and lipids that were not observed in the NIR spectra of the raw samples. Linear discriminate analyses were used to classify fillets as high-WHC or low-WHC according to predicted meat quality characteristics. Using the visible spectra (400–750 nm), fillets could be correctly classified into high-WHC and low-WHC groups based on drip loss and salt-induced water uptake with 88 to 92% accuracy in raw samples and 79 to 86% accuracy in freeze-dried samples. Using the NIR spectra (750–2,500 nm), fillets could be correctly classified into high-WHC and low-WHC groups with 74 to 76% accuracy in raw samples and 85 to 86% accuracy in freeze-dried samples. Thus, freeze-drying enhanced the accuracy of WHC classification using the NIR portion of the spectra. Data from this study demonstrate the potential for utilizing vis/NIR spectroscopy as a method for classifying broiler breast meat according to WHC.

Application of visible and near infrared hyperspectral imaging for non-invasively measuring distribution of water-holding capacity in salmon flesh

Water-holding capacity (WHC) is a primary quality determinant of salmon flesh. One of the limiting factors for not having a direct measurement of WHC for salmon quality grading is that current WHC measurements are destructive, time-consuming, and inefficient. In this study, two hyperspectral image systems operated in the visible and short-wave near infrared range (400–1000nm) and the long-wave near infrared range (897–1753nm) were applied for non-invasive determination of four WHC indices, namely percentage liquid loss (PLL), percentage water loss (PWL), percentage fat loss (PFL), and percentage water remained (PWR) of salmon flesh. Two calibration methods of partial least square regression (PLSR) and least-squares support vector machines (LS-SVM) were applied, respectively, to establish calibration models of WHC indices based on the spectral signatures of salmon flesh, and the performances of these two methods were compared to determine the optimal spectral calibration strategy. The performances were also compared between two hyperspectral image systems, when full range spectra were considered. Out of 121 wavelength variables, only thirteen (PLL), twelve (PWL), nine (PFL), and twelve variables (PWR) were selected as important variables by using competitive adaptive reweighted sampling (CARS) algorithm to reduce redundancy and collinearity of hyperspectral images. The CARS–PLSR combination was identified as the optimal method to calibrate the prediction models for WHC determination, resulting in good correlation coefficient of prediction (rP) of 0.941, 0.937, 0.815, and 0.970 for PLL, PWL, PFL, and PWR analysis, respectively. CARS–PLSR equations were obtained according to the regression coefficients of the CARS–PLSR models and were transferred to each pixel in the image for visualizing WHC indices in all portions of the salmon fillet. The overall results show that the laborious, time-consuming, and destructive traditional techniques could be replaced by hyperspectral imaging to provide a rapid and non-invasive measurement of WHC distribution in salmon flesh.

Relationship between muscle exudate protein composition and broiler breast meat quality

The objective of this study was to determine the relationship between meat quality and the protein content and composition of muscle exudate from broiler breast fillets. Deboned breast fillets (n = 48) were obtained from a commercial processing facility and segregated into 2 groups based on color (light and dark). Meat pH, color, moisture content, 3 measures of water-holding capacity (drip loss, salt-induced water uptake, cook loss), protein solubility, and the protein content of muscle exudates were determined in breast fillets. The protein composition of the muscle exudate was evaluated using SDS-PAGE analysis. Light breast fillets had lower meat pH (4 and 24 h postmortem) and higher L* (lightness) and b* (yellowness) values than dark fillets. Light breast fillets exhibited greater drip loss after 2 and 7 d of storage, lower salt-induced water uptake, and higher cook loss than dark fillets. Neither sarcoplasmic nor total protein solubility differed between light and dark fillets. Protein concentration of muscle exudates was greater in dark fillets and was negatively correlated to drip loss after 2 d of storage (r = −0.50) and salt-induced water uptake (r = 0.42). Electrophoretic protein banding patterns were similar between muscle exudates and sarcoplasmic protein extracts. Gel electrophoresis data from muscle exudates showed that the relative abundance of 4 bands corresponding to 225, 165, 90, and 71 kDa was higher in dark breast fillets. The relative abundance of 3 bands corresponding to 47, 43, and 39 kDa was higher in light breast fillets. Muscle pH and measurements of water-holding capacity were significantly correlated to the abundance of several individual protein bands within the protein profile of muscle exudates. Data from this study showed that protein differences in breast muscle exudates are related to meat pH, color, and water-holding capacity and suggest that muscle exudate could be a potential source of protein markers for fresh meat quality attributes in broiler fillets.

립스틱에서 DSC를 이용한 최대결합수량에 관한 연구

보습제 베이스를 립스틱에 사용하여 보습효과가 우수한 제품개발에 응용하고자 DSC에 의한 결합수형성능, 수분보유능을 고찰하였다. 보습제 베이스를 배제한 견본에서 결합수 형성능은 5.12 %임을 알았다. 보습제 베이스함량에 따른 결합수형성능을 측정한 결과 보습제 베이스 함량이 증가함에 따라 결합수 형성능이 비례적으로 증가함을 DSC측정결과 알았다. 한편 DSC측정결과와 in vitro 수분보유능 측정법을 비교 실험한 결과 유사한 경향을 나타냄을 알 수 있었다. 따라서 DSC에 의한 결합수 형성능 측정법은 앞으로 립스틱 제품의 보습효과를 예측 하는데 유용한 방법으로 생각되었다. To develop lipstick products with superior moisturizing effect using moisture base, bound water capacity and water holding capacity were investigated by DSC. Bound water capacity of the lipstick sample excluding moisture base is found to be 5.12 %. DSC measurement showed that bound water capacity and the concentration of moisture base were positively correlated. Additionally, DSC measurements and in vitro effective water holding capacity measurement showed similar patterns. Therefore, measuring of bound water capacity by DSC can predict the moisturizing effect of lipstick products.

Water-holding capacity, colour stability and sensory characteristics in meat (M. longissimus dorsi) from reindeer fed two different commercial feeds

Twenty reindeer calves (age 10 months) were included in the study. They were all fed one of two different pelleted feed mixtures ad libitum for two months before slaughter. Ten calves were fed a control diet of conventional pellets (CPD) (Renfor Bas, Lantmännen, Holmsund, Sweden) and ten calves received pellets enriched with linseed cake (LPD). The reindeer were slaughtered according to standard procedure at Arvidsjaur Renslakt AB, a reindeer slaughter plant in Arvidsjaur, Sweden. At 1 day post mortem, both longissimus dorsi (LD) muscles from each carcass were excised. The left LD was used for sensory evaluation and the right LD for colour and water-holding capacity measurements. The right LD was cut in 4 pieces that were randomly allocated to storage times of 1 day, 1, 2, or 3 weeks at + 4 °C. Samples allocated for storage were vacuum packaged. Evaluation of meat colour was carried out after each of the four storage times while drip loss/purge was registered after 1, 2, and 3 weeks storage at + 4 °C. The left LD muscles were vacuum packaged, frozen at -20 °C and kept frozen until preparation for sensory evaluation. No significant differences were found in carcass quality (carcass weight, EUROP carcass conformation and fat scores), meat colour stability and water-holding capacity of LD samples when comparing the two treatment groups LPD and CPD. However, sensory panellists judged samples from LPD fed reindeer to have a tendency (not significant) to be more tender (P= 0.06) and juicy (P=0.07) than the meat samples from CPD fed reindeer. No flavour differences were found when comparing meat samples from the two treatment groups.

Heat-Induced Whey Protein Gels: Effects of pH and the Addition of Sodium Caseinate

The effects of pH (6.7 or 5.8), protein concentration and the heat treatment conditions (70 or 90 °C) on the physical properties of heat-induced milk protein gels were studied using uniaxial compression, scanning electron microscopy, differential scanning calorimetry, and water-holding capacity measurements. The systems were formed from whey protein isolate (10–15% w/v) with (5% w/v) or without the addition of caseinate. The reduction in pH from 6.7 to 5.8 increased the denaturation temperature of the whey proteins, which directly affected the gel structure and mechanical properties. Due to this increase in the denaturation temperature of the β-lactoglobulin and α-lactalbumin, a heat treatment of 70 °C/30 min did not provide sufficient protein unfolding to form self-supporting gels. However, the presence of 5% (w/v) sodium caseinate decreased the whey protein thermo stability and was essential for the formation of self-supporting gels at pH 6.7 with heat treatment at 70 °C/30 min. The gels formed at pH 6.7 showed a fine-stranded structure, with great rigidity and deformability as compared to those formed at pH 5.8. The latter had a particulate structure and exuded water, which did not occur with the gels formed at pH 6.7. The addition of sodium caseinate led to less porous networks with increased gel deformability and strength but decreased water exudation. The same tendencies were observed with increasing whey protein concentration.

Correlative responses for carcass and meat quality traits to selection for ovulation rate or prenatal survival in French Large White pigs1

Correlated effects of selection for components of litter size on carcass and meat quality traits were estimated using data from 3 lines of pigs derived from the same Large White base population. Two lines were selected for 6 generations on high ovulation rate at puberty (OR) or high prenatal survival corrected for ovulation rate in the first 2 parities (PS). The third line was an unselected control (CON). The 3 lines were kept for a 7th generation, but without any selection. Carcass and meat quality traits were recorded on the 5th to 7th generation of the experiment. Carcass traits included dressing percentage, carcass length (LGTH), average backfat thickness (ABT), estimated lean meat content, and 8 carcass joint weight traits. Meat quality traits included pH recorded 24 h after slaughter (pH24) of LM, gluteus superficialis (GS), biceps femoris (BF), and adductor femoris (AD) muscles, as well as reflectance and water-holding capacity (WHC) of GS and BF muscles. Heritabilities of carcass and meat quality traits and their genetic correlations with OR and PS were estimated using REML methodology applied to a multiple trait animal model. Correlated responses to selection were then estimated by computing differences between OR or PS and CON lines at generations 5 to 7 using least squares and mixed model methodology. Heritability (h(2)) estimates were 0.08 +/- 0.04, 0.58 +/- 0.10, 0.70 +/- 0.10, and 0.74 +/- 0.10 for dressing percentage, LGTH, ABT, and lean meat content, respectively, ranged from 0.28 to 0.72 for carcass joint traits, from 0.28 to 0.45 for pH24 and reflectance measurements, and from 0.03 to 0.11 for WHC measurements. Both OR and PS had weak genetic correlations with carcass (r(G) = -0.09 to 0.17) and most meat quality traits. Selection for OR did not affect any carcass composition or meat quality trait. Correlated responses to selection for PS were also limited, with the exception of a decrease in pH24 of GS and BF muscles (-0.12 to -0.14 after 6 generations; P < 0.05), in WHC of GS muscle (-18.9 s after 6 generations; P < 0.05) and a tendency toward an increase in loin weight (0.44 kg after 6 generations; P < 0.10) .

Interactions of polysaccharide stabilisers with casein aggregates in stirred skim-milk yoghurt

Abstract The stabilisation mechanisms of low-methoxy pectin, λ -carrageenan, guar gum, locust bean gum and xanthan in stirred yoghurt were investigated using dynamic oscillatory rheometry and water holding capacity measurements. As the level of low-methoxy pectin and λ -carrageenan increased, the stabilisation mechanism was consistent with the model of casein aggregates passing through a region of bridging flocculation, followed by partial steric stabilisation. For guar gum, locust bean gum and xanthan, the results were consistent with depletion flocculation at a low concentration of stabiliser, and trapped aggregated casein within a viscous polysaccharide solution at higher concentrations. A peak was observed for the phase angle of guar-stabilised yoghurt as a function of frequency, from 4.5 to 0.2 Hz as guar increased from 0.5 to 5 g L−1 for 1-day yoghurt, and from 4.5 to 2.2 Hz as the yoghurt containing 0.5 g L−1 guar gum was aged from 1 to 42 days. Results are interpreted with an understanding that the rheological behaviour is affected by the pre-sharing conditions of the stirred yogurt.