卡拉胶对米糠蛋白稳定水包油乳状液乳化稳定性的影响

本研究将卡拉胶添加到米糠蛋白制备的水包油乳状液中,研究不同浓度的卡拉胶（0%、0.2%、0.3%、0.4%、0.5%）对水包油乳状液乳化稳定性的影响。测定了乳状活性、电位、粒径以及分层指数的影响。结果表明,随着卡拉胶浓度的增加,卡拉胶与米糠蛋白共同稳定乳状液的粒径从9.35μm逐渐减小到4.26μm,ζ-电位绝对值从9.45mV显著增大到24.26mV,乳化稳定性从57.79%显著增加到91.54%。卡拉胶使米糠蛋白形成的乳状液的黏度增加6倍,并增强了液滴之间的空间排斥和静电排斥,防止液滴聚集,使乳状液的分层指数明显降低并提高了乳状液的稳定性。可见,卡拉胶具有作为乳状液稳定剂的潜力。     

Effect of pre-dehydration treatment on the in vitro digestibility of starch in cookie

In order to understand the effect of pre-dehydration on the in vitro digestibility of cookie starch, cookie dough samples were dehydrated by vacuum treatment, and melting temperature (T(m)) of the crystalline amylopectin in the dough, internal temperature and water content of the dough during baking, and non-hydrolysed starch content of the obtained cookies were investigated. The T(m) of crystalline amylopectin increased with decreased water content of the dough, and the result was described as a T(m)-curve. The internal temperature of non-dehydrated dough surpassed the T(m)-curve during baking. Pre-dehydrated dough, on the other hand, always indicated a lower internal temperature than the T(m)-curve. The non-hydrolysed starch content obtained under a given condition increased significantly with a decrease in the initial water content of cookies. This will be because the melting of crystalline amylopectin was prevented, at least partially, during baking.     

Investigating the effect of deforming temperature on the oil-binding capacity of palm oil based shortening

This study investigated the effect of deforming temperature on the oil binding capacity (OBC) of a palm oil-based shortening (melting point 40 °C). The shortening was treated with three different temperature conditions namely, Set A at 25 °C for 8 h, Set B at 40 °C for 8 h and Set C at 70 °C for 2 h. Stability analyzer (LUMiFuge, Germany) that applies centrifugal force with an in-built near infrared (NIR) detector was used to measure the amount of free oil released from the shortenings. Other characteristics such as crystal size, solid fat content (SFC), hardness and aerating ability were also studied. The stability analyzer successfully measured the OBC, with the highest in Set A (99%) followed by Set B (94%) and Set C (89%). The increase of deforming temperature resulted in the increase of crystal size that decreased the OBC, which consequently decreased the SFC, hardness and aerating ability of the shortening.     

Water dynamics in white bread and starch gels as affected by water and gluten content

Three levels of water (180, 220 and 260 g/345 g flour) and three levels of gluten (giving 11.2, 13.0 and 14.2 g protein/100 g flour) were used to study the effects of water and gluten on water mobility in white bread using ¹H nuclear magnetic resonance (NMR) relaxometry. Changes in the transverse relaxation time (T₂) were related to water mobility. The three water levels resulted in three different moisture contents in the finished bread (0.55-0.77 g H₂O/g solids). Distributed exponential analysis showed two distinct regions of T₂ (30-600 μs and 1-60 ms), associated with multiple domains of water in the bread crumb. There was no significant difference in peak T₂ values with different gluten content, but significant differences were observed with different moisture content. The results suggested that the mobility of water associated with starch decreased dramatically because of gelatinization. To further investigate the effect of gluten on starch gelatinization, NMR measurements were made directly on model systems containing starch and various gluten amounts. The starch-gluten gels had higher T₂ values than pure starch gels, indicating less swelling of starch granules and absorption of water. This was attributed to less water available to starch in the presence of gluten.     

Effect of monoglyceride organogel structure on cod liver oil stability

The aim of the present research was to study the influence of monoglyceride organogel structure on the oxidative stability of cod liver oil. To this purpose, organogels were prepared by mixing increasing percentages of saturated monoglycerides with cod liver oil, chosen as a natural source of polyunsaturated fatty acids. The structural characteristics of the systems as well as the kinetics of oxidation product formation were evaluated.Increasing the monoglyceride concentration, organogels show an increase of the rheological parameters highlighting different macroscopic structures. On the contrary, at nano-level the systems present the same molecular organization consisting in monoglyceride molecules crystallized in the β-phase and self-assembled in lamellae with a width of around 46 Å.The presence of the monoglyceride network shows a double effect on the oxidative stability of the oil entrapped in the system. It results to be ineffective in affecting the first steps of oxidation but appears a consisting hurdle against the development of secondary oxidation product formation. These results appear interesting in the light of exploitation of organogels to structure liquid oil and thus to product novel health value-added foods.     

Effects of processing conditions and the use of modified starch and monoglyceride on some properties of extruded rice vermicelli

Pasting profile and gel appearance of rice flour, rice flour mixed with the modified starch, MYK-500T and monoglyceride, Monomul 90-35P were examined. The optimum conditions for the extrusion of rice vermicelli obtained were: screw speed 30 rpm; feeder speed, 50 rpm; temperature of three zones, 90 °C:100 °C:100 °C. The rice noodle had white color, good retention of shape but stuck together after cooking. The use of modified starch, and monoglyceride could reduce the stickiness of the product. The noodle extruded from rice flour added with MYK-500T (4 g/100 g blend), and Monomul 90-35P (1 g/100 g blend) was firm and not sticky, showing cooking time at 2 min, cooking weight 315 g/100 g dry noodle, cooking loss 11.1 g/100 g dry noodle and degree of gelatinization 88.9%. The hardness of the product was 1230 g and tensile strength 9.5 g. Sensory evaluation showed that the acceptance of the extruded rice vermicelli was not significantly different from other 3 commercial products prepared by conventional method.     

Effect of bamboo salt on the physicochemical properties of meat emulsion systems

This study was conducted to determine the effects of various bamboo salts on meat batter. To accomplish this, three different batters were prepared and compared: CON, which was prepared with NaCl, BS-2, which was prepared with bamboo salt that was baked twice, BS-9, which was prepared with bamboo salt that was baked nine times. The pH of both the uncooked and cooked BS-2 and BS-9 was higher than that of the CON (P < 0.05). The emulsion stability, cooking yield, water holding capacity (WHC) and apparent viscosity of BS-2 and BS-9 were higher than those of CON. The correlation coefficient between the viscosity value and WHC was high and positive (R² = 0.672). The hardness of all treatments was significantly increased with increased cooking temperature (P < 0.05). The hardness, gumminess and chewiness of CON were higher than that of BS-9 and BS-2. The overall acceptability score between CON and BS-9 was significantly different (P < 0.05). The bamboo salts effectively improved the physicochemical properties of the meat batter.     

Osmotic dehydration of apple: Influence of sugar and water activity on tissue structure,rheological properties and water mobility

Osmotic dehydration of apple tissue (Malus pumila, Granny Smith cultivar) to water activity (a_w) 0.97 or 0.94 with maltose or maltose syrup solutions was studied and compared with previous results using glucose or trehalose as humectants. Structure (optical and transmission electronic microscopy observations), rheological properties (small scale dynamic oscillatory and creep/recovery measurements and large scale compression force-deformation testing), and water mobility (¹H NMR spectra) of parenchymatous apple tissue were significantly affected by osmotic treatments. Osmotically dehydrated apples became soft and extensible and lost crispness and hardness, while the behavior of the moduli G′ and G″ indicated weaker gels after osmosis. Compression properties of the tissues abruptly changed after osmotic dehydration to a_w 0.97, while reduction to a_w 0.94 led to a compression response more similar to that of untreated apples. Compression behavior and state and distribution of water in apple tissues were influenced by the osmotic agent employed and the a_w level, while in general mechanical spectra and creep analysis were not able for distinguishing physical differences between osmotic treatments assayed.     

Influence of main emulsion components on the physical properties of corn oil in water emulsion: Effect of oil volume fraction,whey protein concentrate and Lepidium perfoliatum seed gum

The effect of composition (whey protein concentrate, Lepidium perfoliatum seed gum, and oil content) of corn oil-in-water emulsions on their physical properties, droplet size and viscosity was studied using response surface methodology (RSM). For each response, a second-order polynomial model was developed using multiple linear regression analysis. The results indicated that the response surface models were significantly fitted for all response variables studied. It was shown that all emulsion components greatly influenced the physical properties of emulsion and its overall stability during storage. The main effect of L. perfoliatum seed gum was observed to be significant in most of response surface models. Therefore, the concentration of this gum should be considered as a critical variable for the formulation of emulsions. The overall optimum region resulted in a desirable emulsion was predicted to be obtained by combined level of 0.59% L. perfoliatum seed gum, 6% WPC and 21.95% oil volume fraction.     

Effect of glycerol and vegetable oil on physicochemical properties of Arabic gum-based beverage emulsion

The effect of two emulsion components namely glycerol (0.5, 1 and 1.5% w/w) and vegetable oil (2, 3 and 4% w/w) on ζ-potential, conductivity, pH, apparent viscosity, fluid behavior, turbidity and cloud stability of orange beverage emulsion was investigated. The negatively charged ζ-potential significantly (p < 0.05) increased with increasing glycerol content. A slight increase in ζ-potential was observed by adding 2% (w/w) vegetable oil to the emulsion formulation, while it was slightly decreased when vegetable oil content was increased up to 4% (w/w). Apparent viscosity, pH and turbidity of orange beverage emulsions significantly (p < 0.05) increased when the concentration of glycerol or vegetable oil was increased. All prepared beverage emulsions behaved as non-Newtonian (i.e., pseudoplastic or shear thinning) fluids. The addition of different concentration levels of both supplementary emulsion components except for 0.5% (w/w) glycerol significantly (p < 0.05) improved the cloud stability of orange beverage emulsions.     

Effect of moisture content and water mobility on microwave expansion of imitation cheese

The effects of moisture content (60–45%), and refrigerated storage (1–9 days) on the functional properties, water mobility and microwave expansion of imitation cheese are investigated. Cheese hardness, elastic (G′) and viscous moduli (G″) increased with decreasing moisture content and decreased during storage. Flowability, loss tangent (tan δ) and water mobility decreased with decreasing moisture content and increased during storage. Microwave expansion of imitation cheese decreased with decreasing moisture content and increased with prolonging storage time prior to microwaving. The changes in texture, rheology and flowability of cheese with decreasing moisture content, changes in water mobility and storage time reflected the level of cheese plasticisation by water and had strong linear correlations with microwave expansion. This work provides evidence that moisture content influences microwave expansion of imitation cheese by providing the driving force for expansion and plasticising the cheese matrix.     

Effects of variation in the palm stearin: Palm olein ratio on the crystallisation of a low-trans shortening

Changes in the rheological properties during crystallisation and in the crystal size and morphology of blends containing rapeseed oil with varying percentages of palm stearin (POs) and palm olein (POf) have been studied. The crystals formed from all three blends were studied by confocal laser scanning microscopy, light microscopy and environmental scanning electron microscopy, which revealed the development of clusters of 3–5 individual elementary “spherulites” in the early stages of crystallisation. The saturated triacylglycerol content of the solid crystals separated at the onset of crystallisation was much greater than that in the total fat. Fat blends with a higher content of palm stearin had a more rapid nucleation rate when observed by light microscopy, and this caused an earlier change in the rheological properties of the fat during crystallisation. Using a low torque amplitude (0.005 Pa, which was within the linear viscoelastic region of all samples studied) and a frequency of 1 Hz, the viscoelastic properties of melted fat during cooling were studied. All samples, prior to crystallisation, showed weak viscoelastic liquid behaviour (G″, loss modulus >G′, storage modulus). After crystallisation, a more “solid like” behaviour was observed (G′ similar to or greater than G″). The blend having the highest concentration of POs was found to have the earliest onset of crystallisation (27% w/w POs; 12 mins, 22% w/w POs; 13.5 mins, 17% w/w POs, 15 mins, respectively). However, there were no significant differences in the time to the point when G′ became greater than G′ among the three blends.     

Effect of food preparation on the structure and metabolic responses to a monostearin–oil–water gel-based spread

Widespread recognition of the negative health effects of trans and saturated fats has prompted research to develop alternative structures that can structure liquid oils into semi-solid plastic pastes for food applications. We have recently developed and described the physical chemical properties of a unique a monostearin–oil–water gel (MAG) that achieves this goal. Furthermore, ingestion of this MAG in the form of a margarine-like spread resulted in beneficial suppression of blood lipid and insulin responses in humans compared to compositionally-equivalent controls lacking the MAG structure. However, the integrity of this novel structure and its salubrious metabolic effects have not been previously evaluated under food processing conditions. The purpose of the current study was to evaluate the integrity of the MAG when applied to toasted bread and when mixed with a warm pasta meal, and to evaluate the metabolic effects over 6 h following ingestion of both types of meals with MAG compared to compositionally-equivalent unstructured oil preparations. MAG structure was maintained in the toast study, but the pasta meal destroyed the MAG structure. Triglyceride, free fatty acid, and insulin responses were suppressed in the MAG trial compared to the unstructured oil trial of the toast study, whereas there was no difference in the responses of these variables between the two trials in the pasta study. The results demonstrate for the first time that the metabolic effects of MAG depend on maintenance of the MAG structural integrity throughout the food processing procedures leading up to ingestion. Thus, this study demonstrates the utility of MAG as a trans- and saturated fat-free vehicle to structure and deliver liquid oil as a semi-solid plastic paste, and establishes processing limits to the integrity of the additional beneficial metabolic effects of this novel structure.     

Effect of drying temperature and beeswax content on physical properties of whey protein emulsion films

The objective of this work was to study the effect of drying temperature and the beeswax (BW) content on the physical properties of whey protein emulsion films. For this purpose, films were obtained by the casting method and dried at two selected temperatures (5 and 25 °C). Film thickness, water vapor permeability (WVP), solubility and mechanical properties were measured. The results showed that the decrease in drying temperature from 25 to 5 °C reduced the WVP and increased the solubility of the films containing BW. The effect of drying temperature on the mechanical properties was significant in the tensile test but not in the puncture test. The addition of BW decreased the WVP and the solubility and also had a significant effect on the evaluated parameters in both mechanical tests. In general, this effect was observed at both drying temperatures studied. Therefore, taking into account the several applications of the coatings the optimization of coating formulations and drying conditions is of vital importance.     

乳清蛋白-黄油乳液凝胶对低脂酸奶理化特性及品质的影响

乳液凝胶是一种新型的脂肪替代物,乳清蛋白和黄油是乳品中常用的原、辅料,利用乳清蛋白和黄油制作的乳液凝胶在乳制品加工中具有良好的应用前景.制备不同蛋白和脂肪含量的乳清蛋白-黄油乳液凝胶颗粒(whey protein-butter emulsion gel particles,WPI-EG),研究其对低脂酸奶理化特性及感官...     

Effect of chitosan on the stability and properties of modified lecithin stabilized oil-in-water monodisperse emulsion prepared by microchannel emulsification

The effect of chitosan (CHI) on the stability of monodisperse modified lecithin (ML) stabilized soybean oil-in-water (O/W) emulsion was investigated. Monodisperse emulsion droplets with particle size of 24.4 ± 0.7 μm and coefficient of variation below 12% were prepared by microchannel (MC) emulsification using a hydrophilic asymmetric straight-through MC silicon 24 × 24 mm microchip consisting of 23,348 microchannels. The stability of the ML stabilized monodisperse emulsion droplets was investigated as a function of CHI addition at various concentration, pH, ionic strength, thermal treatment and freezing-thawing treatment by means of particle size and ζ-potential measurements as well as microscopic observation. The monodisperse O/W emulsions were diluted with CHI solution at various concentrations to a final droplet concentration of 1 wt% soybean oil, 0.25 wt% ML and 0–0.5 wt% CHI at pH 3. Pronounced droplet aggregation was observed when CHI was present at a concentration range of between 0.01 and 0.04 wt%. Above this concentration range, flocculations were less extensive, indicating some restabilization. ML stabilized emulsions were stable at a wide range of NaCl concentrations (0–1000 mM) and pH (3–8). On the contrary, in the presence of CHI, aggregation of the emulsion droplets was observed when NaCl concentration was above 200 mM and when the pH started to approach the pKa of CHI (i.e. ∼6.2–7.0). Emulsions containing CHI were found to have better stability at high temperature (>70 °C) in comparison to the emulsion stabilized only by ML. With sucrose/sorbitol as cryoprotectant aids, emulsions with the addition of CHI were found to be more resistant to droplet coalescence as compared to those without CHI after freezing at −20 °C for 22 h and thawing at 30 °C for 2 h. The use of CHI may potentially destabilize ML-stabilized O/W emulsions but its stability can be enhanced by selectively choosing the appropriate CHI concentrations and conditions of preparation.     

Bread staling: Effect of gluten on physico-chemical properties and molecular mobility

Three gluten enriched breads were produced (5% and 15% gluten samples where water was adjusted with farinograph determination, and a 15% sample with the same water amount of the control). The effect of gluten on bread staling (7 days) was evaluated, focussing on texture, amylopectin retrogradation, water status and ¹H molecular mobility.     

氨基硅油用作施胶剂对纸张性能的影响

乳液是不溶于水的助剂的主要应用形式,将氨基硅油制成乳液,用作纸张施胶剂。研究发现,随着氨基硅油用量的增加,纸张的强度下降,纸张施胶度明显提高,在氨基硅油的用量占绝干浆的0.8%时,纸张的施胶度可以达到21.5s。     

Effect of soy residue (okara) on in vitro protein digestibility and oil release in high-calorie emulsion stabilized by heated mixed proteins

This study investigated the influences of a dietary fiber source – namely okara powder (OKP) and pectinase-hydrolyzed okara powder (PHO) – on the physicochemical characteristics of a high-calorie emulsion (1 kcal/mL) stabilized by sodium caseinate and soy protein isolate at a ratio of 0.7:0.3, with caloric distribution from carbohydrate:protein:lipid of 55:15:30. The viscosity and microstructure of the emulsion containing 0.08% (w/v) crude fiber and its digesta were monitored during in vitro protein digestion by pepsin and trypsin, along with the interfacial protein content in the cream phase, the soluble protein content in the serum phase, and oil release during the course of digestion. Use of OKP induced the formation of a thick paste under acidic conditions, and oil could be released after 15 min digestion by pepsin. On the other hand, the presence of PHO increased the viscosity of the emulsion under acidic pH to less extent than did the OKP and delayed the release of oil for up to 105 min during peptic digestion. The oil could be released from PHO-containing digesta after tryptic digestion, both in the absence and presence of bile acid. The study indicated that the rate of nutrient release can be controlled by the presence and type of dietary fiber source.