Effect of β-carotene on vitamin A light stability in fortified milk

The effect of incorporation of β-carotene into the carrier system on the light stability of all-trans retinyl palmitate in fortified skim milk was investigated. Skim milk was fortified with all-trans retinyl palmitate using corn oil with and without added β-carotene as the vitamin carrier. Two levels of β-carotene were used, one similar to, the other half the concentration of vitamin A in the carrier system. After homogenization and pasteurization, fortified milk samples were exposed to fluorescent light (1614 lx) at 4°C in glass tubes.

Less light degradation of all-trans retinyl palmitate occurred in samples containing added β-carotene in the carrier systems compared to samples without added β-carotene. The β-carotene content of fortified milk samples showed only a slight decrease over the four-day period of exposure.     

Relationship between UVA protection and skin response to UV light: proposal for labelling UVA protection

Definition and validation of a most relevant method to assess ultravoilet A (UVA) protection is a major concern for industry, authorities and consumers. However, due to the lack of knowledge about all the biological phenomena involved, the level of UVA protection needed, the ways to assess and label it, remain controversial. In order to overcome this situation, the paper deals with the outcomes of a mathematical model to calculate the distribution between ultravoilet B (UVB) and UVA components of skin responses to UV light. Mathematical calculations of UVB and UVA erythemal components of skin response to sunlight are developed from the well-known determination procedure to calculate the sunburn protection factor (SPF) of sunscreens. The model establishes the relationship between the UVA component of skin erythemal response to overall UV radiation received from sunlight and the ratio SPF/PFAe (erythemal protection factor) where SPF is the product and PFAe is related to the UVA part of the sunlight. Depending on the efficacy profile of sunscreens, the skin erythemal response may be mainly promoted by UVB rays as it normally occurs in unprotected skin or on contrary by UVA rays. Therefore, the efficacy profile of sunscreens defines the deepness where biological events induced by sunlight take place. This new relationship pinpoints the tremendous importance of the protection afforded by sunscreen products in the UVA range when erythema is taken as biological response. By extrapolation of the model to any other biological skin response it becomes possible to predict how to improve the efficiency of sunscreen products in the future. UVA protection afforded by sunscreens should be improved until reaching the same level as the SPF protection factor so that all UV-induced biological responses could be prevented or lowered at the same extend. To enforce this improvement, a proposal to classify sunscreen products in relation with their UVA protection is made.     

Protective effect evaluation of free radical scavengers on UVB induced human cutaneous erythema by skin reflectance spectrophotometry

This paper assesses the suitability of UVB induced skin erythema measured by reflectance spectrophotometry in humans as a model for differentiating topical efficacy of free radical scavengers. Two different formulations (aqueous gels and O/W emulsions) of each active compound (tocopherol, tocopherol acetate, superoxide dismutase (SOD), glutathione, ascorbyl palmitate) were tested on healthy human volunteers before and after skin exposure to UVB radiation. Skin erythema was monitored by calculating erythema index values from the skin spectral data obtained using a reflectance spectrophotometer. The free radical scavengers tested were not able to inhibit UVB induced skin erythema from both formulations when they were topically applied before UVB irradiation. Applying the free radical scavenger formulations after skin exposure to UVB radiation, glutathione and SOD showed the best ability in inhibiting the induced erythema (percentage inhibition 53.3 and 41.6%, respectively from gels). Tocopherol and tocopherol acetate inhibited UVB skin erythema by 27% while ascorbyl palmitate showed a poor efficacy. For all the active compounds tested, no significant difference was observed comparing the results obtained from gels to those from emulsions. Liposomal gel formulations containing the free radical scavengers which showed the best activity (SOD and glutathione) were prepared and topically applied after skin exposure to UVB radiation. SOD and glutathione liposomal formulations were more effective than the corresponding conventional gels. The proposed model, if validated by further studies, could be useful for differentiating the effectiveness of free radical scavengers in inhibiting photoaging due to long-term sunlight skin exposure.     

Modulation of fat-soluble vitamin concentrations and blood mononuclear leukocyte populations in milk replacer-fed calves by dietary vitamin A and beta-carotene

Dairy calves (n = 18), separated from dams at birth, were fed 1 L of pooled-colostrum. For the remaining 7 wk of the study, they were fed one of three diets consisting of either a custom-formulated milk replacer without vitamin A (controls), or supplemented with retinyl palmitate (equivalent to 32,000 IU of vitamin A/d) or with beta-carotene (equivalent to 20,000 IU of vitamin A/d). Plasma retinol, beta-carotene, and RRR-alpha-tocopherol concentrations were lowest at birth, and increased substantially from birth to 1 wk postpartum in all groups, a probable consequence of ingestion of colostrum. From 1 to 7 wk of age, retinol concentrations were greatest in retinyl palmitate-supplemented calves, intermediate in beta-carotene-supplemented calves and lowest in control calves. At 2, 3, 5, 6, and 7 wk, RRR-alpha-tocopherol concentrations were lower in retinyl palmitate-supplemented calves than in control calves. A negative correlation between plasma retinol and vitamin E concentrations existed from wk 2 to 7, suggesting vitamin A influences the absorption and distribution of RRR-alpha-tocopherol. Supplemental retinyl palmitate, but not beta-carotene, was associated with a reduction in the percentage of blood mononuclear leukocytes expressing CD2, CD4, and CD8-T cell antigens and interleukin-2 receptors. By wk 7, leukocyte populations from retinyl palmitate-supplemented calves were more similar to those from adult cattle than those from control calves, suggesting that supplemental vitamin A, as retinyl palmitate, affects the maturation of the neonatal immune system. Differences in the composition of blood mononuclear leukocyte populations may represent changes in immune competency.     

Factors related to the light stability of vitamin A in various carriers

Skim milk fortified with all-trans retinyl palmitate, using corn or coconut oil as the vitamin carrier, was studied to determine the effect of physical state and droplet size of the carrier system on loss of all-trans retinyl palmitate during exposure to light. To determine effect of physical state, fortified samples were exposed to light at 4 degrees C, where corn oil is liquid and coconut oil solid, or 35 degrees C where both oils are liquid. At 4 degrees C, rates of light degradation of all-trans retinyl palmitate in corn or coconut oil were significantly different from each other; at 35 degrees C they were not. Different droplet sizes of the carrier systems were achieved by homogenizing skim milk at different pressures (169, 105, or 35 kg/cm2). In all cases, greater loss occurred in corn oil as the vitamin carrier compared to coconut oil. Degradation rate of all-trans retinyl palmitate increased with decreased homogenization pressure. Effects of photooxidation of fatty acids on degradation of all-trans retinyl palmitate and isomerization of retinyl palmitate were investigated in four carrier systems (corn, butter, peanut, and coconut) by exposing the fortified oils to light. Peroxide values did not parallel degradation of all-trans retinyl palmitate during light exposure. Isomerization of all-trans to cis isomers of retinyl palmitate occurred in all carrier systems.     

Effect of Carrier Type and Amount on Vitamin A Light Degradation in Fortified Lowfat and Skim Milks

Effects of type and amount of retinyl palmitate carrier on light stability of all-trans retinyl palmitate in fortified lowfat milks were investigated. Skim and 2% fat milks were fortified with retinyl palmitate using butter, coconut, corn, or peanut oil as the vitamin carrier. After pasteurization and homogenization, fortified milk samples were exposed to light in glass tubes. At regular intervals, samples were removed from light and analyzed for all-trans retinyl palmitate using high performance liquid chromatography. Less light-induced loss of all-trans retinyl palmitate occurred in skim and 2% fat milks fortified using butter or coconut oil than those using corn or peanut oil. Amount of coconut or corn oil used to incorporate retinyl palmitate also played a role in its light-induced degradation rate. At a carrier concentration of .001% (vol/vol) in skim milk, light degradation of all-trans retinyl palmitate proceeded approximately twice as fast as .01 or .1% (vol/vol). Addition of Tween 80 as an emulsifier had negligible effect on retinyl palmitate light degradation in fortified skim milk.     

Binding of lipophilic nutrients to beta-lactoglobulin prepared by bioselective adsorption

The binding of the lipophilic nutrients, retinal, vitamin D2, and retinyl palmitate by beta-lactoglobulin was measured by analysis of changes in the fluorescence of the tryptophanyl residue of beta-lactoglobulin or the retinyl moiety. The fluorescence intensity of the tryptophanyl residue was quenched by retinoid or vitamin D binding but was enhanced by palmitate binding. The analysis of competitive binding experiments with palmitate indicated that retinal and palmitate did not compete for the same site; however, vitamin D2, which binds with a stoichiometry of 2, appeared to displace palmitate at higher concentrations. Also, the retinoids and vitamin D2 were bound more tightly than was palmitate. The results are consistent with the model in which the retinoids and vitamin D2 bind in the calyx formed by the beta-barrel; palmitate and a second molecule of vitamin D2 bind in a surface pocket near the dimer contact region. Retinyl palmitate, which has both moieties, appeared to bind at both sites.     

Stability of vitamin A palmitate in cosmetic emulsions: influence of physical parameters

The aim of this work was to verify if a close relationship exists between the physical stability of an emulsion and the chemical stability of vitamin A palmitate included in it. Oil-in-water cosmetic emulsions with high viscoelastic properties were prepared, and their rheological behaviour was investigated in oscillatory conditions. The stability of each sample was verified in high-temperature stress conditions: periodical checks of physical parameters and chromatographic analysis of vitamin A were performed during storage. Results show that the chemical stability of vitamin A palmitate strictly depends on the physical stability of the formulation and in particular on the presence of a coherent gel-like structure in the external phase of the emulsion.     

Vitamin A Stability in Ultra-High Temperature Processed Milk

Stability of vitamin A in partly skimmed (2% fat) fortified and unfortified ultra-high temperature processed milk was examined over 15 wk. Milk samples (stored at 23 ± 2°C) were analyzed weekly for retinyl palmitate and dissolved oxygen. Significant losses of 71 and 73% were observed in replicate samples of fortified milk containing initial vitamin A of 119 and 91 µg retinyl palmitate/100 ml, respectively. An unfortified milk sample with initial vitamin A of 86 µg retinyl palmitate/100 ml showed a loss of 62% whereas the replicate sample with initial vitamin A of 28 µg retinyl palmitate/100 ml remained unchanged during storage. Dissolved oxygen in all four milk samples underwent significant changes. During the first 7 wk, oxygen declined or remained constant. After 7 wk, oxygen in all samples steadily increased.     

Quantitative determination of vitamin A in liver and liverwurst using high pressure liquid chromatography (HPLC)

Samples of liver sausage and liver tissue from slaughtered animals were analysed for pre-formed vitamin A. A sensitive reversed phase HPLC method with fluorescence detection was used to determine the amount of free and esterified retinol in extracts of these samples. Under our chromatographic conditions retinyl myristate and linoleate run together as do retinyl palmitate and oleate. The contents of all forms of vitamin A were expressed in milligrams of all-trans retinol per 100 g wet weight. The average concentrations of total vitamin A for turkey, pig, calf, beef, and chicken liver were 42.31, 38.15, 22.74, 14.98, and 13.22, respectively. In addition to these differences, the fatty acid composition of liver retinyl esters, as well as the amount of retinol, also varied considerably among species. Approximately 95% of the hepatic vitamin A was present as retinyl ester with retinyl palmitate/oleate as the main ester fraction. The second most abundant fatty acid in the retinyl ester fraction of calf, beef, and chicken liver was stearic acid followed by myristic/linoleic acid. An increment of retinol, however, was also found in these tissue samples. By contrast, in turkey liver the retinol fraction was increased and therefore both retinyl stearate and retinol were present in nearly equal amounts, whereas the retinyl ester fatty acids from pig liver contained relatively more myristate/linoleate and less stearate than those from liver of the other domestic animals (apparently a hallmark of pig liver). The retinol and retinyl ester pattern present in liver sausage was similar to, but not identical with, that of pig liver.(ABSTRACT TRUNCATED AT 250 WORDS)     

Viscous and thermal behaviour of vitamin A and iron‐fortified reconstituted rice

The viscous and thermal behaviour of five types of micronutrient‐fortified reconstituted rice premixes extruded at pre‐optimised extrusion conditions (36% moisture content, 150 rpm screw speed and 89 °C barrel temperature) have been investigated using rapid visco analyser (RVA) and differential scanning calorimetry (DSC). The highest peak viscosity (1279 cP), lowest gelatinised starch percentage (16.32) and highest enthalpy of gelatinisation (8.2 J g^?1) were recorded in rice premix fortified with retinyl palmitate and micronised ferric pyrophosphate. The scanning electron microscopic analysis (SEM) also revealed that reconstituted rice premix fortified with iron (micronised ferric pyrophosphate) and retinyl palmitate was in closer resemblance to that of natural rice than any other reconstituted rice premix. The work demonstrated that vitamin A‐ and iron‐fortified reconstituted rice with meso/micro structure and pasting behaviour close to that of natural rice can be produced using retinyl palmitate and micronised ferric pyrophosphate as vitamin A and iron source, respectively.     

FUNCTIONAL PROPERTIES OF HIGH HYDROSTATIC PRESSURE-TREATED WHEY PROTEIN

Surface hydrophobicity, solubility, gelation and emulsifying properties of high hydrostatic pressure (HHP)‐treated whey protein were evaluated. HHP treatment of whey protein buffer or salt solutions were performed at 690 MPa and initial ambient temperature for 5, 10, 20 or 30 min. Untreated whey protein was used as a control. The surface hydrophobicity of whey protein in 0.1 M phosphate buffers treated at pH 7.0 increased with an increase in HHP treatment time from 10 to 30 min. HHP treatments of whey protein in salt solutions at pH 7.0 for 5, 10, 20 or 30 min decreased the solubility of whey proteins. A significant correlation was observed between the surface hydrophobicity and solubility of untreated and HHP‐treated whey protein with r = ?0.946. Hardness of HHP‐induced 20, 25 or 30% whey protein gels increased with an increase in HHP treatment time from 5 to 30 min. An increase in the hardness of whey protein gels was observed as whey protein concentration increased. Whey proteins treated in phosphate buffer at pH 5.8 and 690 MPa for 5 min exhibited increased emulsifying activity. Whey proteins treated in phosphate buffer at pH 7.0 and 690 MPa for 10, 20 or 30 min exhibited decreased emulsifying activity. HHP‐treated whey proteins in phosphate buffer at pH 5.8 or 7.0 contributed to an increase in emulsion stability of model oil‐in‐water emulsions. This study demonstrates that HHP treatment of whey protein in phosphate buffer or salt solutions leads to whey protein unfolding observed as increased surface hydrophobicity. Whey proteins treated in phosphate buffers at pH 5.8 and 690 MPa for 5 min may potentially be used to enhance emulsion stability in foods such as salad dressings, sausage and processed cheese.     

Effects of different oils on the properties of soy protein isolate emulsions and gels

The emulsion properties, protein adsorption and visco-elastic properties of heat-treated soy protein isolate (SPI) emulsions containing sunflower oil, soy oil and palm stearin were studied at neutral pH. The rheological properties, textural profile and fat adsorption capacity of subsequently induced glucono-δ-lactone (GDL) gels were investigated. At neutral pH the palm stearin emulsions showed higher stability than the sunflower and soy oil emulsions. The former also showed higher protein adsorption, emulsifying activity index and visco-elastic properties than the latter, indicating a higher denaturation degree for SPI at the oil/water interface of palm stearin emulsions at neutral pH. Acidified SPI-palm stearin emulsion gels were significantly harder than the soy and sunflower oil versions as well as the control (SPI without oil), whereas gels containing the two liquid oils were softer than the control. SPI-palm stearin gels also had higher fat adsorption capacity than SPI-sunflower oil/soy oil emulsion gels.     

Effect of emulsifiers and fortification methods on light stability of vitamin A in milk

Lowfat milk is commercially fortified during processing by adding small quantities of oil containing an emulsifier and vitamin A. Added vitamin A is degraded more rapidly than indigenous vitamin A when milk is exposed to light. The objective of this research was to determine if added vitamin A could be made as stable to light as naturally occurring vitamin A by placing it in the more dilute milk fat environment with naturally occurring emulsifiers. Using HPLC to quantify retinyl palmitate, the effect of emulsifiers indigenous to milk versus a commercial emulsifier was first investigated. Butter serum, rich in fat globule membrane material, was compared with Durfax 80 in a 1% recombined milk system. No difference was found in vitamin A stability to light due to emulsifier type. A second experiment on 1% milk compared light stability of vitamin A added in concentrated milk fat emulsion, vitamin A added to all the milk fat, and indigenous vitamin A. Indigenous vitamin A and vitamin A added to all the fat were equally stable and more stable than vitamin A added in a concentrated milk fat emulsion.     

Heat Stability of Oil-in-Water Emulsions Containing Milk Proteins: Effect of Ionic Strength and pH

Emulsions (20 wt% soybean oil; 2 wt% protein) made with caseinate at pH 7 and with whey protein isolate (WPI) at pH 7 and 3 were stable to heating at 90 and 121°C. WPI emulsions destabilized at pH values between 3.5 and 4.0. In the presence of KCI (12.5–200 mM), large particles were formed in WPI emulsions at pH 3 and the emulsions were viscous. At pH 7, moderate concentrations of KCI decreased the heat stability and gels were formed. KCI had less effect on WPI emulsions made at pH 3. Combining the emulsions with caseinate allowed some control of the heat-induced gelation.     

VC脂质体水凝胶的制备及其消化特性研究

将脂质体和水凝胶结合,以卡拉胶和乳清分离蛋白通过酶和离子交联形成凝胶,将维生素C(VC)脂质体包埋于其中形成VC脂质体水凝胶.通过表征脂质体水凝胶在不同储存时间的磷(Pi)释放量和脂质氧化程度,以及模拟消化过程中的平均粒径及粒度分布,脂质体和乳清分离蛋白的降解,VC的释放量,研究脂质体水凝胶的储存稳定性和体外消化稳定性...     

Gelation and Emulsification Properties of Partially Insolubilized Whey Protein Concentrates

Ultrafiltered retentate of whey was heat-processed to prepare whey protein concentrates (WPC) with protein solubilities ranging from 27.5% to 98.1% in 0.1M NaCl, pH 7.0. Proximate and protein compositions of each WPC were determined. Properties of 20% (w/w) protein WPC gels in 0.1M and 0.6 M NaCl, pH 7.0, on heating to 60, 70, 80, and 90°C and emulsification properties of WPC (0.5% (w/w) protein) in 0.1M NaCl at pH 6.0, 7.0 and 8.0 were analyzed. Gel apparent stress and strain at failure decreased and expressible moisture increased as solubility decreased from 98.1% to 41.0% at all heating temperatures. Emulsification Activity Index was highest at pH 7.0, emulsions were most stable at pH 8.0.     

Stability of Retinyl Palmitate During Cooking and Storage in Rice Fortified with Ultra RiceTM Fortification Technology

Rice fortified with Ultra Rice^TM (UR) containing retinyl palmitate (RP) was tested as a potential vehicle for vitamin A delivery. After UR was mixed with a long grain rice at the ratio of 1 to 99 (w/w), the stability of RP in the rice mixture was studied during cooking and storage for 6 mo. After cooking, the percent retention range of RP was 75 to 87, depending upon the cooking methods. The stability of RP in the rice stored at 2 different temperatures and relative humidities (RH) appeared to be more affected by temperature than RH. Therefore, under tropical conditions, rice fortified with RP might require special handling to avoid significant RP losses.     

Effect of Milk Fat on the Stability of Vitamin A in Ultra-High Temperature Milk

The stability of vitamin A in ultra-high temperature milks with .15, 2.92, 6.16, and 9.7% fat during storage at 26°C was studied over 3 wk. Milks were fortified with synthetic retinyl palmitate to a final concentration of approximately 120 μg retinol equivalent/I 00 ml milk. The four milk samples were ultra-high temperature processed and packaged in 100 ml sterile milk dilution bottles and stored in the dark at 26°C for 3 wk. Vitamin A concentrations decreased rapidly during the first 2 wk of storage then stabilized. Degradation rates during the first 2 wk were linear and varied inversely with the fat content in the milk (the more fat, the slower the rate of degradation). Final vitamin A concentrations at the end of 3 wk of storage were higher in milk with high fat and closely corresponded to the native vitamin A concentrations present in milk prior to fortification. The results indicate a possible protective effect due to fat or a difference in stability between native and synthetic vitamin A.     

植物球蛋白/姜黄素纳米复合物的制备及其对O/W型Pickering乳液氧化稳定性影响

本论文以两类植物球蛋白:豌豆分离蛋白(PPI)和大豆分离蛋白(SPI)为材料制备荷载姜黄素蛋白纳米复合物,并探究荷载前后蛋白所制备乳液的物理和氧化稳定性差异。结果表明:PPI和SPI在pH 3.0和pH 7.0下荷载前后蛋白纳米颗粒粒径没有明显变化。pH 7.0时两蛋白姜黄素荷载量均高于pH 3.0,各pH下SPI荷载量要高于PPI。表面疏水性的显著降低与荧光淬灭现象发生表明形成两种蛋白纳米复合物的主要作用力为疏水相互作用,同时在两pH下,PPI比SPI荧光蓝移趋势更明显且有效淬灭常数也更大,即更易形成复合物。与原蛋白相比,荷载后各蛋白颗粒所制备乳液乳化活性有少许降低,同时pH 3.0时各蛋白颗粒乳化活性要高于pH 7.0。各乳液生成初级氧化产物脂质氢过氧化物浓度的变化趋势与生成次级氧化产物TBARS相类似,均为荷载姜黄素后各乳液氧化水平加速,同时pH 3.0时各类型乳液油滴氧化程度均高于pH 7.0。