Study on the applicability of high-pressure homogenization for the production of banana juices

The aim of this preliminary study was to evaluate the potential applicability of high-pressure homogenization (HPH) for the production of banana juices. To this purpose, a prototype equipment working up to 400 MPa and a lab-scale homogenizer working up to 150 MPa were used. Temperature, microbial load, pectate lyase activity, colour and viscosity of the samples homogenized at increasing pressure were evaluated. Pressures higher than 200 MPa were needed to obtain 4 log unit reduction of total mesophilic bacteria and pectate lyase inactivation. Following HPH, banana juice resulted brighter and less viscous than the untreated one. Data suggest that HPH treatments could be a reliable technological alternative to conventional heat treatments for the production of added-value fruit juices. However, the homogenization design could play a critical role in affecting the product quality attributes. In fact, homogenization performed at the same operative pressure by using different equipment leads to different effects on product quality.     

带肉胡萝卜汁的流变特性研究

本文研究了不同温度、浓度和不同均质压力处理的带肉胡萝卜汁的流变特性，发现带肉胡萝卜汁的表观粘度随果肉浓度的增大而增大：随温度的升高而减小；而随着均质压力的增大则出现先增大后减小的规律。     

Influence of oat gum, guar gum and carboxymethyl cellulose on the perception of sweetness and flavour

The influence of three pseudoplastic hydrocolloids, oat gum, guar gum and carboxymethyl cellulose (CMC) on sensory perception of sweetness and flavour was studied in model systems at two viscosity levels. The sweeteners studied were sucrose, fructose and aspartame, the flavour substances ethyl caproate, a-pinene and cinnamic acid. Sweetness was best perceived from oat gum solutions and most weakly from guar gum solutions. The effect of the composition of the thickener on the perception of sweetness was greater than that of viscosity. Reduction of sweetness by hydrocolloids was weaker for aspartame than for fructose or sucrose. In the perception of flavours, both the total length of perception and the time-intensity pattern were more dependent on the model aroma substance than on the thickener. Possible explanations for the differences are discussed.     

Relating Creamy Perception of Whey Protein Enriched Yogurt Systems to Instrumental Data by Means of Multivariate Data Analysis

Yogurts differing in fat content, protein content, and casein to whey protein ratio were produced, and structurally as well as sensorially examined. The objective of the current research was to evaluate the predictive value of rheological and particle size measurements concerning sensory appearance and texture attributes in 13 differently composed stirred yogurt systems, with a focus on graininess, viscosity, and creaminess. Structural and sensory analyses showed large differences in texture properties between the tested yogurt systems. Both data sets were correlated by means of multivariate statistical methods. Sensory graininess was highly correlated with particle size‐related parameters, sensory viscosity was highly correlated with destructive rheological parameters, and creamy perception was highly correlated with particle size‐related parameters and destructive rheological parameters but was not as well described by any oscillatory parameter. Best predictive ability (r² > 0.89) was found for creaminess combining particle size related‐ and destructive rheological parameters tested within this study. Practical Application : Knowing the instrumental parameters describing sensory textural attributes provides important information for having a better understanding of the underlying processes during consumer's perception. Knowledge about the sensory behavior of a product and its oral processing imparts an opportunity to fasten the product development process. By means of yogurt systems instrumental parameters derived from particle size analysis and rheological measurements were correlated with sensory attributes in order to determine the main factors leading to the mouthfeel sensations grainy, viscous, and creamy of semisolid milk products.     

Effect of high pressure homogenization (HPH) on the rheological properties of a fruit juice serum model

High pressure homogenization (HPH) is a non-thermal technology that has been widely studied as a partial or total substitute for thermal food processing. The present work evaluated the effect of HPH on the rheological properties of a fruit juice serum model, designed to be similar to tomato juice serum. Product viscosity decreased due to the increase in homogenization pressure, and could be modelled well using two functions (power-sigmoidal and exponential; R² > 0.98). The serum model processed at 200 MPa showed a viscosity decrease of 20% when compared to the original. Since fruit juice rheology is defined by the interactions occurring between the dispersed phase (suspended particles) and the solution (serum), the expected fruit juice behaviour was then discussed.     

Xanthan, Hydroxypropyl Methyl Cellulose and High Fructose Corn Syrup Sensory Effects in a Reduced Calorie Syrup Model

Reduced calorie fruit syrup model systems were prepared using xanthan (0.01–0.49%), hydroxypropyl methyl cellulose (HPMC) (0.2–0.8%), and high fructose corn syrup (HFCS) (33–43% soluble solids). A central composite design was used to formulate 15 different products for study using response surface methodology (RSM). The model syrups were tested for viscosity; pH; percent solids; and the following sensory attributes: pourability, thickness, slipperiness, absorption into pancakes, sweetness and off-flavors. Viscosity, pourability, slipperiness, and absorption into pancakes highly correlated with each other. Higher gum levels increased viscosity and slipperiness but decreased pourability and absorption into pancakes. Increased solid levels were associated with decreased viscosity and slipperiness. Sweetness perception was not affected.     

高压均质协同高酰基结冷胶对青椒蛋蔬液流变特性及稳定性的影响

研究高压均质（high pressure homogenization,HPH）协同高酰基结冷胶（high acyl gellan gum,HA）处理对青椒蛋蔬液（liquid egg with green pepper juice,LEGP）稳定系数、持水力、流变特性、粒径及电位的影响,进而探讨HPH协同HA对LEGP流变特性及稳定性的影响。结果表明：HPH处理可以明显提高LEGP的稳定系数、持水力、屈服应力、表观黏度和ζ-电位绝对值,并减小体系粒径,说明HPH处理可以有效提高LEGP体系稳定性。与HPH相比,HPH协同HA处理可以进一步提高LEGP的稳定系数、持水力、屈服应力、表观黏度和ζ-电位绝对值,使体系粒径进一步减小且分布更均匀,表明HPH协同HA处理可以更好地提高LEGP体系稳定性;其中,均质压力为150 MPa时,LEGP的稳定系数和持水力达到最大。流变实验结果表明HPH处理或HPH协同HA处理样品的流变模型均符合Herschel-Buckley模型,且其流体为带屈服值的假塑性流体,其中,HPH协同HA处理均质压力为150 MPa时,LEGP的屈服应力、表观黏度和弹性模量最高,流体的假塑性最强,体系粒径最小,ζ-电位绝对值最大,LEGP表现出最高的稳定性。     

Effect of cream homogenization on textural characteristics of low-fat Iranian White cheese

The effects of cream homogenization of cheese making milk on textural and sensory characteristics of Iranian White cheese were studied. Cream was homogenized in a two-stage homogenizer at 6.0/2.5 or 9.0/2.5 MPa. Cheese samples were analyzed for rheological parameters (uniaxial compression and small amplitude oscillatory shear), meltability, microstructure, and sensory characteristics. Cream homogenization increased fat content leading to increased meltability. This effect increased as the homogenization pressure increased. The values of storage modulus, stress at fracture and Young's modulus of elasticity for cheeses from homogenized treatments were lower than those of unhomogenized cheese. Cream homogenization at 6.0/2.5 MPa effectively improved the textural, functional and sensory characteristics and enhanced the yield of low-fat Iranian White cheese. This cheese had the lowest values of storage modulus and stress at fracture, probably due to the high number of small, evenly dispersed fat globules in microstructure and especially its lower protein content. Cheeses with homogenized cream had improved texture, flavor and appearance.     

Dual-attribute Time-intensity Measurement of Sweetness and Peppermint Perception of Chewing Gum

The relationship between duration and maximum intensity of sweetness and peppermint flavor of chewing gum was explored using dual-attribute time-intensity sensory evaluation. Four chewing gum samples, varying in rate of release of sweetness and peppermint flavor were evaluated by 10 trained time-intensity panelists. Chewing gum with a fast release of sweetness and peppermint flavor provided the highest maximum intensity and longest duration of sweetness and peppermint perception. The rate of release of sweetness was more important than rate of release of peppermint flavor in affecting duration of attributes.     

Dynamic high pressure-induced gelation in milk protein model systems

The structure-functional properties of milk proteins are relevant in food formulation. Recently, there has been growing interest in dynamic high-pressure homogenization effects on the rheological-structural properties of food macromolecules and proteins. The aim of this work was to evaluate the effects of different homogenization pressures on rheological properties of milk protein model systems. For this purpose, sodium caseinate (SC) and whey protein concentrate (WPC) were dispersed at different concentrations (1, 2, and 4%), pasteurized, and then homogenized at 0, 18 MPa (conventional pressure, CP), 100 MPa (high pressure, HP), and 150 MPa (HP+). Differences in viscosity were observed between WPC and casein dispersions according to concentration, heat treatment, and homogenization pressure. Mechanical spectra described the characteristic behavior of solutions except for the WPC 4% pasteurized sample, in which a network formed but was broken after homogenization. Dispersions with different ratios of WPC and SC were also made. In these systems, pasteurization alone did not determine network formation, whereas homogenization alone promoted cold gelation. A total concentration of at least 4% was required for homogenization-induced gelation in pasteurized and unpasteurized samples. Gels with higher elastic modulus (G′) were obtained in more concentrated samples, and a bell-shaped behavior with the maximum value at HP was observed. The HP treatment produced stronger gels than the CP treatment. Similar G′ values were obtained when different concentrations, pasteurization conditions, and homogenization pressures were combined. Therefore, by setting appropriate process conditions, systems or gels with tailored characteristics may be obtained from dispersions of milk proteins.     

葫芦巴胶改善吞咽障碍者饮水安全性的流变学研究

参照美国吞咽障碍膳食标准,以样品的 η50黏度为分类依据,将葫芦巴胶制备成黏度分别为180 cP(花蜜型)、1000 cP(蜂蜜型)和2500 cP(布丁型)的增稠流体,对其流变学性质进行研究,并评价葫芦巴胶用于改善吞咽障碍者的饮水安全性.结果表明,溶解温度是葫芦巴胶流变性质能否满足改善饮水安全性要求的关键.80℃制备...     

Effect of high-pressure homogenization on droplet size distribution and rheological properties of ice cream mixes

The effect of different homogenization pressures (15/3 MPa and 97/3 MPa) on fat globule size and distribution as well as on structure-property relationships of ice cream mixes was investigated. Dynamic light scattering, steady shear, and dynamic rheological analyses were performed on mixes with different fat contents (5 and 8%) and different aging times (4 and 20 h). The homogenization of ice cream mixes determined a change from bimodal to monomodal particle size distributions and a reduction in the mean particle diameter. Mean fat globule diameters were reduced at higher pressure, but the homogenization effect on size reduction was less marked with the highest fat content. The rheological behavior of mixes was influenced by both the dispersed and the continuous phases. Higher fat contents caused greater viscosity and dynamic moduli. The lower homogenization pressure (15/3 MPa) mainly affected the dispersed phase and resulted in a more pronounced viscosity reduction in the higher fat content mixes. High-pressure homogenization (97/3 MPa) greatly enhanced the viscoelastic properties and the apparent viscosity. Rheological results indicated that unhomogenized and 15/3 MPa homogenized mixes behaved as weak gels. The 97/3 MPa treatment led to stronger gels, perhaps as the overall result of a network rearrangement or interpenetrating network formation, and the fat globules were found to behave as interactive fillers. High-pressure homogenization determined the apparent viscosity of 5% fat to be comparable to that of 8% fat unhomogenized mix.     

Effect of whey and pea protein blends on the rheological and sensory properties of protein-based systems flavoured with cocoa

Whey and pea protein combined in different proportions (100W:0P, 75W:25P, 50W:50P, 25W:75P, 0W:100P) were used to prepare protein-based systems flavoured with cocoa and containing κ-carrageenan or κ-carrageenan/xanthan gum as thickeners. Steady and dynamic shear rheological properties of samples were measured at 10 °C and sensory differences were evaluated. Protein-based systems exhibited a shear-thinning flow behaviour that was fitted to the simplified Carreau model. Samples showed different viscoelastic properties, ranging from fluid-like to weak gel behaviour. For both types of system (with and without xanthan gum) viscosity, pseudoplasticity and elasticity rose on increasing the pea protein proportion in the blend. The sample with only whey protein obeyed the Cox-Merz rule, while in the rest of the samples complex viscosity was higher than apparent viscosity. Regarding sensory properties, the protein blend ratio mainly affected sample thickness, which rose as pea protein proportion increased. However, at the same time, the chocolate flavour and sweetness decreased and the off-flavour increased.     

Viscosity drives texture perception of protein beverages more than hydrocolloid type

Hydrocolloids are added to alter rheological properties of beverages but have other properties that can contribute to overall taste and texture perception. In this study, tapioca starch and λ-carrageenan were used to determine how hydrocolloid type, viscosity level (4–6 mPa·s, 25–30 mPa·s, and 50–60 mPa·s at 50 s⁻¹), and complexity of the system (aqueous, skim milk, or whole milk) influence sensory taste and texture of fluids. All fluids were shear thinning; however, skim milk and whole milk solutions that contained carrageenan had much higher low shear viscosity and lower high shear viscosity than those with starch. There was a significant effect of viscosity level on sensory perception of consistency, creamy/oily, mouthcoating, and residual mouthcoating in aqueous, skim milk, and whole milk beverages, and a weak effect of hydrocolloid type. However, normalizing creamy/oily, paste, and mouthcoating against sensory consistency removed the effect of hydrocolloid type. Flavors (cream, cooked, cardboard, and melon/cardboard) were associated with the type of hydrocolloid and milk protein ingredient. Temporal dominance of sensations showed that samples exhibit similar temporal sensory profiles, although the addition of hydrocolloids enhanced dominance of creaminess even in samples without fat. Hydrocolloid type did not significantly influence mouthcoating or the persistence of astringency. Additionally, increasing viscosity from 3 to 74 mPa·s at 50 s⁻¹ did not suppress perceived sweet or salty taste. The results suggest that in fluid systems with viscosity levels typically found in beverages, textural properties are determined by viscosity and independent of the type of hydrocolloid.     

Oil-in-water emulsions stabilized by sodium caseinate: Influence of pH,high-pressure homogenization and locust bean gum addition

The effect of pH, addition of a thickening agent (locust bean gum) or high-pressure homogenization on the stability of oil-in-water emulsions added by sodium caseinate (Na-CN) was evaluated. For this purpose, emulsions were characterized by visual analysis, microstructure and rheological measurements. Most of the systems were not stable, showing phase separation a few minutes after emulsion preparation. However, creaming behavior was largely affected by the pH, homogenization pressure or locust bean gum (LBG) concentration. The most stable systems were obtained for emulsions homogenized at high pressure, containing an increased amount of LBG or with pH values close to the isoelectric point (pI) of sodium caseinate, which was attributed to the size reduction of the droplets, the higher viscosity of continuous phase and the emulsion gelation (elastic network formation), respectively. All the studied mechanisms were efficient to decrease the molecular mobility, which slowed down the phase separation of the emulsions. In addition, the use of sodium caseinate was also essential to stabilize the emulsions, since it promoted the electrostatic repulsive interactions between droplets.     

Flaxseed oil – Whey protein isolate emulsions: Effect of high pressure homogenization

The effect of high-pressure homogenization (20–100 MPa) and the number of homogenization cycles (1–7) on the stability of flaxseed oil - whey protein isolate emulsions was evaluated. All the emulsions were stable to creaming for at least 9 d of storage. An increase in homogenization pressure from 20 to 80 MPa and number of passes through the homogenizer up to 3, decreased the mean droplet size of the O/W emulsions despite the higher polydispersity. Emulsions homogenized at lower pressures (20 MPa) showed a monomodal distribution of the particles, whereas, an increase in pressure to 80 MPa led to a bimodal distribution, indicating droplets coalescence. High-pressure homogenization (80 MPa) and an increase in the number of homogenization cycles, led to the formation of high molecular weight aggregates (>200 kDa), which favored an increase in viscosity of the emulsions. The increase in homogenization pressure also increased the formation of primary oxidation products, which could be explained by the increase in temperature and in the surface area of the droplets.     

Effect of emulsifier type and homogenization temperature and pressure on physical properties of peanut extract

Peanut extract (90.4% moisture, 3% protein and 4.5% fat, w/w) was homogenized using a two-valve homogenizer and the effects of emulsifier and homogenization temperature and pressure on the physical properties were studied. Homogenization without emulsifier at 72°C increased the emulsion stability (ES) and sedimentation index (SI) by 5–11% and 15% respectively, compared to homogenization at 60°C. Homogenization with gum arabic increased the ES and viscosity by 17–22% and 127–176% respectively, and decreased SI by 26–38%. Homogenization with soya lecithin increased the ES and viscosity by 28–33% and 16–18% respectively, and decreased SI by 35–44%. Homogenization with Recodan EMS® (monodiglycerides + glycerol monostearates + soya lecithin) or Recodan CM® (monodiglycerides + glycerol monostearates + guar gum + carrageenan) increased the ES and colour lightness (L*) by 43–60% and 12% respectively, and decreased SI by 44–48%. Addition of Recodan CM® increased the viscosity by 482%. ES and L* increased with pressure. Extracts homogenized without emulsifier, with gum arabic, soya lecithin or Recodan EMS® were Newtonian whereas the extract homogenized with Recodan CM® was pseudoplastic.