肉桂酸基油脂凝胶的制备及其流变特性和结晶特性分析

选择米糠油为溶剂体系,肉桂酸作为凝胶剂制备油脂凝胶,借助流变仪、X-射线衍射仪、荧光显微镜研究其流变特性及结晶特性。结果表明：米糠油凝胶的持油性和熔点随肉桂酸添加量的增加逐渐增加,当肉桂酸添加量超过10%,油脂凝胶的持油性和熔点增加不显著（P＞0.05）;米糠油凝胶的持油性随加热温度升高迅速上升,在85?℃时升高至93.62%,此时的凝胶熔点也相对较高;当冷却温度从0?℃升高至5?℃时,凝胶的持油性和熔点相对较高,当冷却温度进一步升高,凝胶的持油性和熔点显著下降至93%（P＜0.05）。通过对肉桂酸添加量10%、加热温度85?℃、冷却温度5?℃形成的油脂凝胶进行流变学特性分析,发现该油脂凝胶呈现假塑性流体状态,样品的表观黏度-剪切速率的关系符合幂律方程关系;并且在频率扫描范围内,油脂凝胶体系的储能模量（G’）明显大于损耗模量（G”）,样品形成较为紧密的凝胶结构;通过凝胶结晶特性分析发现,米糠油凝胶中的结晶结构细小,分布均匀,存在同质多晶现象,主要含有β和β′?2?种晶体类型。     

Altering Functional Properties of Fats Using Power Ultrasound

ABSTRACT: Ultrasound has been used for the last 50 y in different processing applications. Depending on the power and frequency of the sound waves, ultrasound techniques can be classified in different categories. Low-intensity ultrasound uses high frequencies in the range of 100 kHz to 10 MHz and is mostly used for therapeutic purpose (frequencies between 1 and 10 MHz) and to passively monitor the characteristics of materials (frequencies between 100 kHz and 10 MHz). High-intensity ultrasound (HIU), on the other hand, uses lower frequencies in the range of 20 to 100 kHz and it is commonly used for cleaning, disrupting, and restructuring materials. The objective of this study is to evaluate the effect of HIU on functional properties of anhydrous milk fat (AMF), palm kernel oil (PKO), and an all-purpose shortening (Sh). Results from this research shows that HIU induced primary and secondary nucleation in the lipid, generating smaller crystals and as a consequence harder materials. HIU affected hardness more efficiently when applied at higher crystallization temperatures (26 and 28 °C) as shown for AMF data, and when the sonication was applied after the first crystals were formed as observed for PKO and Sh systems. In addition to changes in hardness, AMF and Sh networks obtained after sonication were characterized by a steeper and sharper melting profile. This research shows that HIU can be used as an additional processing tool to tailor the functional properties of lipids with the potential to be used in the processing of trans-free shortenings.     

Effect of high intensity ultrasound on physicochemical and functional properties of soybean glycinin at different ionic strengths

In this work, soybean glycinin was treated by high intensity ultrasound (HIU; 20 kHz at 80 W cm^− 2 from 0 to 40 min) in three ionic strengths (I = 0.06, 0.2 and 0.6) at pH 7.0. At all three ionic strengths, HIU of glycinin increased emulsion stability and decreased the turbidity. However, the effects of HIU on the particle size, particle distribution, solubility, emulsifying activity index, and surface hydrophobicity showed different characteristics in three ionic strengths. For example, after HIU, surface hydrophobicity of glycinin increased at I = 0.06 and 0.2, but remained unchanged at I = 0.6. The effects of HIU on glycinin were more pronounced at I = 0.2 than the other two ionic strengths. Furthermore, HIU influenced the glycinin aggregates, but remained the secondary and tertiary structures almost unchanged, which could be demonstrated by circular dichroism and the intrinsic fluorescence spectra.Industrial relevanceSoy protein is a plant protein which is widely employed in food products due to its high nutritional value, low price as well as its good functional properties. However, soy protein, especially glycinin, is easy to form aggregates and therefore limits soy proteins'application in some aspects. High intensity ultrasound (HIU) waves are generally considered as safe, non-toxic, and environmentally friendly. The results of this study suggested that HIU could dissociate soy glycinin and improve some functional properties of soybean glycinin, indicating that HIU can be considered as a potential tool to change soy glycinin's functional property. Moreover, this work found that the effects of HIU on physicochemical and functional properties of soybean glycinin were different in three ionic strengths, which could provide some fundamental information on how HIU influences the soy glycinin structures in different ionic strength and increase the application of HIU in the soy bean industry.     

Physical properties of emulsion gels formulated with sonicated soy protein isolate

This study aimed to determine the effect of high-intensity ultrasound (HIU) on physical properties of soy protein isolate dispersions (SPI) and their addition to emulsion gels (EG) containing soybean oil (SBO), inulin (IN) and carrageenan (CAR). Sonicated and non-sonicated SPI dispersions were mixed with CAR, IN and SBO and heated at 90 °C for 30 min to gel the emulsion. An increase in solubility and oil binding capacity was observed in sonicated SPI dispersions (S-SPI) compared to the non-sonicated ones. HIU changed the molecular weight of SPI and decreased apparent viscosity in the dispersions. The use of S-SPI in the EG reduced the droplet size and increased the hardness and G′ values. The use of S-SPI allowed a reduction of 75% of carrageenan in the EG without affecting the hardness of the gel. The results suggest that HIU can be used to improve rheological properties of functional EG.     

Degree of oxidation of sonicated soybean oil using various sonication process parameters

This research aimed to examine the effect of high-intensity ultrasound (HIU) on the oxidation of soybean oil (SBO). Samples (5, 100, and 250 g) were sonicated at 25 °C using various sonication conditions: power level (settings 1, 5, and 9), tip size (12.7, 3.2, and 2 mm), and duration (5, 10, and 60 s). After sonication, the degree of oxidation of samples (sonicated and non-sonicated SBO) were analysed using peroxide value (PV), oil stability index (OSI), and volatile compounds. Sonication was applied to obtain a range of absolute power (0–123.5 W), power density (0–14.2 W cm⁻³), and power intensity (0–1,120 W cm⁻²) values. The highest power density and power intensity were obtained with the highest HIU setting with the 3.2 mm tip. The highest power was obtained when HIU was applied using a 12.7 mm tip and setting 9 in 250 g of sample. No significant difference (P > 0.05) was observed in PV (0.20 ± 0.01 mEq kg⁻¹) nor OSI (10.05 ± 0.04 h), among the various sonication conditions tested. In addition, no differences were observed in the volatile compounds obtained. These results show that HIU can be used under mild sonication conditions such as the ones needed to change the physical properties of lipids without causing oxidative deterioration.     

Optimisation of soya bean oil bleaching by ultrasonic processing and investigate the physico‐chemical properties of bleached soya bean oil

In this study, an ultrasonic bleaching method for soya bean oil under different conditions was optimised by monitoring the reduction of oil‐containing colourants. Ultrasonic power, clay content, temperature and time had a significant interaction effect on (P < 0.05) the reduction of oil pigments and colourants. Under optimised conditions, red and yellow colour indices in the ultrasound‐bleached soya bean oil reduced to 74.44% and 75.55%, and 54.18% and 58.85%, respectively, at amplitudes of 85% and 65%. Carotenoid and chlorophyll concentrations also reduced to 81.19% and 83.62%, and 94.66% and 95.26%, respectively, at 85% and 65% ultrasonic power. The overall contents of sterols and tocopherols decreased using ultrasonic bleaching process compared with the neutralised soya bean oil. Although the peroxide value (PV) of the soya bean oil after ultrasonic and control bleaching reduced, this index was higher in the ultrasonic bleached oil than the control one. The results showed that the ultrasonic bleaching process could be an alternative to the industrial bleaching method as it reduced clay usage, temperature and time of bleaching about 35%, 35% and 10%, respectively.     

Effects of high intensity ultrasound and emulsifiers on crystallization behavior of coconut oil and palm olein

The objective of this research is to evaluate the crystallization behavior of coconut oil (CO) and palm olein (PO) as affected by the addition of two monoacylglycerols (MAG) emulsifiers and by the use of high intensity ultrasound (HIU). MAG with high content of palmitic, oleic, and linoleic acid (EM1) and MAG with high content of stearic acid and no unsaturated fatty acids (EM2) were used. Results show that the addition of emulsifiers did not affect crystallization kinetics of CO and similar solid fat contents (1.32 ± 0.94) (SFC) and melting enthalpies (5.90 ± 4.56) were obtained. The addition of EM1, however, significantly delayed the crystallization of PO as evidenced by a significantly lower SFC and melting enthalpy. SFC for PO was 8.56 ± 0.913 while SFC for PO + EM1 was 3.63 ± 1.38. Sonication induced the crystallization of CO samples crystallized with and without EM1 and EM2 while only induced the crystallization of PO + EM1 as measured with SFC. The induction in crystallization by HIU was also evidenced by higher enthalpy with values up to a range of 8 J/g to 11 J/g. A decrease in elasticity from 3.17 × 10⁶ to 2.52 × 10⁵ was observed in CO crystallized with emulsifiers which could be reverted by the application of HIU. Contrarily, the addition of emulsifiers increased elasticity of PO from 3.35 × 10² to 4.83 × 10⁴ and sonication did not affect these values significantly. Differences observed in elasticity values are attributed not only to the amount of solid material obtained but also to the type of microstructure of the crystalline network formed during crystallization.     

Controlled ice nucleation under high voltage DC electrostatic field conditions

The quality of frozen food and the preservation of the microstructure of the tissue depend on the nucleation rate. As the nucleation rate is related to supercooling, the control of supercooling is highly desirable. In this study, a novel approach is proposed to control ice nucleation using high electrostatic field. Distilled water has been considered as a model food. An original experimental set-up, consisting of pair of plate electrodes and cooling–heating system (Peltier element), has been designed. During sample cooling, high DC voltage was applied to a flat electrode located above the sample. The electrostatic field used in the experiments ranged from 0 V/m to 6.0 × 10⁶ V/m. It was found that with the increase of applied voltage, nucleation temperature was shifted towards higher values. Other tests were conducted to clarify the capability of electrostatic field to induce ice nucleation at a desired supercooling degree. Our experimental results revealed that utilization of sufficiently high electrostatic field is a reliable method to control ice nucleus formation.     

Reduction of cyanide content of bitter almond and its oil using different treatments

To reduce the cyanide content of bitter almond oil, four treatments were investigated. The optimal parameters were obtained, under which loss of cyanide of 79.4%, 87.2%, 98.3% and 98.4% were achieved for baking, microwave, water boiling and ultrasonic treatment, respectively. The effects of treatments on the physicochemical properties of bitter almond oil showed no significant differences. All treatments could reduce the cyanide content in bitter almond oil, and ultrasonic treatment was the most optimal treatment. The loss of cyanide was 98.4% when the ultrasonic power was 700 W for 50 min of treatment. Ultrasonic power and time had remarkable effect on the reduction of cyanide content. The proposed treatments could be applied to reduce the cyanide content in bitter almond oil.     

An innovative method of immersion vacuum cooling for cooked meat products: immersion vacuum cooling with ultrasonic assistance

In this paper, immersion vacuum cooling with ultrasonic assistance (IVCUA) is compared with immersion vacuum cooling alone (IVC) and vacuum cooling (VC) for cooling time, mass loss, colour, texture profile and water mobility and compartmentalization for cooked meat products. The results reveal that IVCUA clearly enhances the boiling intensity of impregnation liquid compared to IVC. The total cooling time using IVC (126.56 min) for samples from 72 to 4 °C was significantly longer (P < 0.05) than that of IVCUA (96.89 min) and VC (80.48 min). The cooling time of samples from 10 to 4 °C by IVC (46.26 min) was higher (P < 0.05) than that by IVCUA (28.55 min). There were no significant differences (P > 0.05) in mass loss, colour and texture profile among all samples. However, IVCUA had a higher transverse relation time of bulk water (T₂₄) and MRI proton densities (P < 0.05), as well as a more uniform water distribution compared to IVC.     

Properties of Cookies Made with Natural Wax–Vegetable Oil Organogels

The aim of this study was to examine the feasibility of cookies in which the conventional margarine is replaced with an organogel of vegetable oil (VO) and natural wax. New cookies from VO organogels contain no trans fats and much less saturated fats than cookies made with a conventional margarine. To understand the effects of different kinds of waxes, organogels were prepared from 4 different waxes including sunflower wax (SW), rice bran wax (RBW), beeswax, and candelilla wax and properties of cookie dough and cookie were evaluated. To investigate the effects of different VOs on the properties of cookies, 3 VOs including olive oil, soybean oil and flaxseed oil representing oils rich in oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3), respectively, were used. Both the wax and VO significantly affected properties of organogel such as firmness and melting behavior shown in differential scanning calorimetry. The highest firmness of organogel was observed with SW and flaxseed oil. Properties of dough such as hardness and melting behavior were also significantly affected by wax and VO while trends were somewhat different from those for organogels. SW and RBW provided greatest hardnesses to cookie dough. However, hardness, spread factor, and fracturability of cookie containing the wax–VO organogel were not significantly affected by different waxes and VOs. Several cookies made with wax–VO organogels showed similar properties to cookies made with a commercial margarine. Therefore, this study shows the high feasibility of utilization of the organogel technology in real foods such as cookies rich in unsaturated fats.     

葵花籽油凝胶油的制备及其在冰淇淋中的应用

以葵花籽油为原料,添加一定量的蜂蜡或蜂蜡与谷维素混合物制备葵花籽油凝胶油,研究不同添加量的凝胶因子对葵花籽油凝胶油的硬度值、黏度值、持油性和微观形态的影响;将得到的凝胶油代替黄油制备冰淇淋,研究其在冰淇淋中的应用。结果表明:蜂蜡添加量对凝胶油的质构特性、持油性和微观形态影响较为显著,并确定5%蜂蜡添加量为凝胶油制备的最优条件;添加5%复合凝胶油(5%蜂蜡+1%谷维素)和5%黄油制备的冰淇淋营养丰富、抗融性好、色泽均匀、组织细腻、滑润爽口,与添加10%黄油制备的冰淇淋较为相近,表明可以通过进一步的优化代替饱和脂肪在冰淇淋中应用。     

高强度超声作用下鲢鱼肌球蛋白的结构及流变学特性变化

以鲢鱼为原料提取纯化肌球蛋白,研究不同高强度超声处理条件（100、150、200、250 W分别超声3、6、9、12 min）下肌球蛋白链构象、二级结构及流变学特性的变化。结果表明：超声处理会降低肌球蛋白的低温自组装程度,使样品的零剪切黏度逐渐降低、流动性增大,并诱导肌球蛋白α-螺旋向较为松散的β-折叠和无规卷曲结构转变,促使包埋在分子内部的活性基团暴露出来。该结构变化有利于升温过程中分子间的交联,并降低凝胶化温度,适当的超声条件（100、150 W处理12 min）可提高肌球蛋白的凝胶形成能力,而超声功率过大（200、250 W处理12 min）则会降低其凝胶形成能力,选择适当的超声条件对鱼糜凝胶加工十分重要。     

Induction Time of Crystallization in Vegetable Oils, Comparative Measurements by Differential Scanning Calorimetry and Diffusive Light Scattering

ABSTRACT: In this work we compared the induction time of crystallization (τ_i. measured by DSC (τ_iDSC) and scanning diffusive light-scattering (SDLS, τ_iSDLS) in a vegetable oil blend. Several crystallization temperatures and cooling rates (1,10, and 30 °C/min) were investigated. Additionally, rheograms obtained during the crystallization of the oil blends were obtained to differentiate the stages of nucleation and crystal growth. The results obtained showed that independent of cooling rate and crystallization temperature, SDLS provided an earlier detection of triacylglycerides'(TAGS) nucleation than DSC. Furthermore, τ_iSDLS was more consistent (that is, lower standard deviation) than τ_iDSC particularly at high crystallization temperatures and cooling rates. The rheograms showed that τ_iDSC involves a measurement of crystal growth, while τ_iSDLS is associated with the early formation of a solid phase in the oil blend (that is, TAGS nucleation). When the Fisher-Turnbull equation was therefore used to calculate the free energy of nucleation (ΔG_c), τ_iSDLS provided a better estimate of ΔG_c than that obtained by τ_iDSC     

Influence of Ultrasound on Freezing Rate of Immersion-frozen Apples

The use of power ultrasound within the food industry is an innovative subject. Application of sound to monitor a process or product is common, e.g. in quality assurance. However, the use of ultrasound to directly improve processes and products is less popular in food manufacturing. In the present work, ultrasound-assisted immersion freezing was investigated on apple samples. Because the apple parenchyma is mechanically anisotropic, the influence of applying ultrasound on radial or tangential orientated samples was also examined. Apple cylinders were immersed in an ultrasonic bath system, which operates at 40 kHz frequency. Experiments were carried out at a power level of 131.3 W (0.23 W/cm²), and ultrasound was applied intermittently for different times from temperatures below and close to the initial freezing point. Results showed that ultrasound application at 0°C or −1°C for 120 s in total, with 30 s intervals, significantly improved the freezing rate represented by the characteristic freezing time up to 8% (P < 0.05), compared to immersion freezing without ultrasound. Results of the effect of ultrasound waves applied on radial or tangential cut samples sonicated for 120 s from −1°C and/or 0°C indicated that at the power level considered there were no significant differences among the ultrasonic radial or tangential irradiated samples of these treatments, though the freezing rates were enhanced and different (P < 0.05) from the control treatment. Some evidence of the influence of ultrasound to induce primary nucleation was also observed.     

Oxidative stability of solid fats containing ethylcellulose determined based on the headspace oxygen content

Solid fat was developed by blending fully hydrogenated soybean oil, palm oil, and canola oil, and organogels were prepared using selected solid fats and ethylcellulose. The oxidative stability of organogel was tested at 100 and 180°C using a headspace oxygen assay. Addition of ethylcellulose produced a firmer organogel solid state in selected solid fats ranging from 15.8 to 24.6% saturation at room temperature. Addition of ethylcellulose generally decreased the oxidative stability of organogels prepared using canola oil. The oxidative stability of some organogels made using solid fats changed depending on the concentration of added ethylcellulose (10 or 15%, w/w), and the oxidation temperature. Development of an organogel with a relatively low saturation and a high oxidative stability suitable as a food ingredient is possible.     

Thermal behavior of concentrated oil-in-water emulsions based on soybean oil and palm kernel olein blends

Droplet size distribution and thermal behavior of concentrated oil-in-water emulsions based on soybean oil (SBO)/palm kernel olein (PKO) blends were investigated. The emulsions were prepared using 70% (wt./wt.) oil blends of SBO/PKO as dispersed phases and stabilized by egg yolk. An increase in PKO level (0–40% wt./wt.) in the oil dispersed phase volume fraction caused significant increases (p < 0.05) in volume-weighted mean diameter (d_4,3). The DSC data suggested that crystallization of the emulsions was induced by a ‘template effect’ of yolk constituents via a surface heterogeneous nucleation. Emulsions with 0–20% (wt./wt.) PKO levels in the dispersed phase demonstrated a good cool–heat stability even after three successive thermal cycles (from 50 °C to ?70 °C at 10 min/°C). After the first thermal cycle, emulsions with 30% and 40% PKO levels in the oil dispersed phase were destabilized due to strong coalescence and crystallized via volume-surface heterogeneous nucleation. The unstable emulsions were attributable to high level of saturated triacylglycerols from PKO, with high droplet size characteristic, causing them to be more prone to partial coalescence.     

Effects of Organogel Hardness and Formulation on Acceptance of Frankfurters

Different organogel formulations used as beef fat (BF) replacement (0%, 20%, 40%, 60%, and 80%) were utilized to optimize the mechanical properties of frankfurters. Organogels, made of canola oil (CO), included different concentrations of ethyl cellulose (EC) and sorbitan monostearate (SMS). They consisted of: 8% EC + 1.5% SMS referred to as organogel‐I (OG‐I), 8% EC + 3.0% SMS (OG‐II), and 10% EC + 1.5% SMS (OG‐III), which were found promising in a previous study when used at 100% replacement. Replacement of BF with organogels at all levels could bring down the very high hardness values (texture profile analysis and sensory) of frankfurters prepared using CO by itself, relative to the BF control. OG‐I and OG‐II quantity had no significant effect on hardness and springiness, being similar in many cases to the BF and lower than the CO control. Shear force values of all organogel treatments were not significantly different from one another, and were between the BF and CO controls. Smokehouse yield showed a pattern of decreasing losses with increasing organogel replacement level. Sensory analysis revealed that using CO by itself significantly increased hardness, but structuring the oil (via organogelation), brought it down to the BF control value in all OG‐I and OG‐II formulations. Juiciness was significantly reduced by using liquid oil but increased with raising the amount of organogels. Oiliness sensation increased with higher organogel substitution and was actually higher than the beef control. The study demonstrates the potential use of vegetable oil structuring in replacing the more saturated BF in emulsion‐type meat products.     

Effects of different nut oils on the structures and properties of gel-like emulsions induced by ultrasound using soy protein as an emulsifier

Gel-like emulsions were produced by high-intensity ultrasound (HIU) emulsification using soy protein as an emulsifier. Sunflower (a seed kernel oil), peanut (a groundnut oil), hazelnut, walnut, almond and pine nut oils were chosen as oil phases. The kinds of nut oil significantly affect the structures and properties of gel-like emulsions. The particle size of sunflower oil gel-like emulsion was smallest. Moreover, the macrorheological and microrheological results indicated that the values of apparent viscosity, storage modulus (G′) and elasticity index (EI) of sunflower and almond oil gel-like emulsions were higher while those of the walnut and pine nut oil gel-like emulsions were lower. Moreover, the sunflower oil gel-like emulsion was more stable after 2-month storage. The current study illustrated that HIU was of great importance for the production of high-viscosity gel-like emulsions. Furthermore, the differences of nut oils resulted in diverse physicochemical properties of gel-like emulsions.     

酸溶条件及高强度超声波对鲢鱼肉分离蛋白的提取及凝胶特性的影响

研究了不同酸溶条件（鱼肉匀浆液的pH值）和高强度超声波（High Intensity Ultrasonic treatment, HIU）对酸溶等电点沉淀法鲢鱼肉分离蛋白（protein isolate, PI）的提取、蛋白组成以及凝胶特性的影响。数据显示：降低pH能显著提高蛋白回收率（由pH 4.0到3.0,提高了21.11%）,但pH<3.0时,进一步降低pH对蛋白回收率不再有提高作用;HIU显著提高了蛋白回收率（pH 3.0时,提高了3.77%）;PI中以肌原纤维蛋白为主,pH降低能够显著减少等电点处可溶性中等分子蛋白种类及浓度,而HIU对此影响不大。pH降低和HIU均会增加PI凝胶亮度（89.24→94.25）和白度（83.24→88.45）。HIU显著提高了PI凝胶硬度（1531.74→1756.24 g）,降低pH能够提高PI凝胶硬度（1162.55→1683.41 g）,但当3.0后,作用不显著。pH低于4.0时,pH变化和HIU对PI凝胶弹性无显著影响（0.792~0.823）。降低pH和HIU引起PI凝胶蒸煮损失率的显著增加（2.05%→4.43%）。结论：极酸pH（pH<3.0）并不会提高蛋白回收率,且对PI凝胶特性无益。采用pH 3.0的酸溶条件并辅以HIU,能够得到最高的蛋白回收率及最优的PI凝胶特性。