Spray drying of low‐phenylalanine skim milk: optimisation of process conditions for improving solubility and particle size

The optimisation of the spray drying process for low‐phenylalanine skim milk as a dietary supplement for phenylketonurics was studied. The effects of basic parameters including the inlet air temperature (100, 150 and 200 °C), feed flow rate (5, 10 and 15 mL min^?1) and air flow rate (400, 600 and 800 L h^?1) on the solubility and particle size of the low‐phenylalanine skim milk powder were determined using response surface methodology. The optimum conditions have been obtained with inlet air temperature of 133 °C, feed flow rate of 5 mL min^?1, and air flow rate of 800 L h^?1. With the optimum parameters, the predicted values for the solubility and mean diameter were 95.33% and 5.34 μm, respectively, and experimentally were 94.36 ± 1.62% and 5.50 ± 0.44 μm, respectively. The experimental and predictive values were closely related showing predictive accuracy of the models.     

Evaluation of spray drying conditions on properties of microencapsulated oregano essential oil

Response surface methodology (RSM) was employed to investigate variations in powder characteristics with respect to spray drying operating parameters including both feed rates (L min^?1) and inlet temperatures (°C). Inlet temperatures around 180 °C provided the lowest values for moisture. Powder recovery was significantly affected (P < 0.10) by inlet air temperature and feed rate, where a raise in inlet temperature and feed rate resulted in higher powder recovery. No significant difference (P > 0.05) was observed for water activity, solubility and hygroscopicity between treatments. Regarding oil retention, the results showed a significant (P < 0.05) interaction between the two studied factors. A tendency for higher values of oil retention was observed when using combinations of high inlet temperatures/low feed rates and low inlet temperatures/high feed rates. Particle size distribution averaged 2.0, 8.1 and 18.3 μm for D₁₀, D₅₀ and D₉₀, respectively. The morphology of particles showed no cracks in most capsules. The results indicate that high temperature (185 °C) and moderated feed rate (0.63 L min^?1) are the best spray drying conditions.     

Optimisation of spray drying process parameters for low‐fat honey‐based milk powder with antioxidant activity

The purpose of this study was to optimise process parameters to prepare spray‐dried honey‐based milk powder containing functional properties of honey. Experimental design with temperature (180 to 200 °C), honey concentration (5–15%) and feed flow rate (8–10 rpm) as independent variables was studied to investigate the effect on product responses. Results showed that increasing the temperature resulted in powder with lower moisture, bulk density, antioxidant activity, total phenolic contents, total flavonoid contents and higher water solubility index. Increasing feed flow rate resulted in higher moisture, bulk density, antioxidant activity, reduced water solubility index, total phenolic content and total flavonoid content, whereas increasing honey concentration resulted in increase in antioxidant activity, total phenolic content and total flavonoid content. The moisture content, bulk density, water solubility index, DPPH scavenging activity, total phenolic content and total flavonoid content were 3.27%, 0.44 g cc^?1, 96.67 g g^?1, 17.45%, 2.54 GAE g^?1 powder and 1.40 RE g^?1 powder, respectively.     

Study on the spray-drying encapsulation of lutein in the porous starch and gelatin mixture

Spray-drying encapsulation of lutein was conducted to improve its stability and water-solubility. With the porous starch and gelatin as wall material, lutein microcapsules were effectively prepared by spray-drying process. Results showed the optimal technology of lutein encapsulation as follows: the ratio of core to wall material of 1/30, embedding temperature of 60 °C, embedding time 1.5 h, inlet gas temperature of 190 °C, feed flow rate 50 mL/min and drying air flow 60 m³/h, at which the microcapsules had good encapsulation efficiency (94.4 ± 0.4)% and high yield of product (92.6 ± 1.7)%. Its solubility was increased and it could be directly dissolved in water. The stability of lutein microcapsule in the new carrier mixture against heat, pH, light and oxygen was also greatly improved and their retention rates had been improved about 15–50% than that of free lutein. The results would be helpful to the application of lutein in food industry.     

Optimisation of a pilot‐scale spray drying process for probiotic yoghurt,using response surface methodology

The influence of drying air temperatures, drying air flow rate and feed flow rate on percentage survival rate (% SR) of starter and probiotic bacteria, moisture content, water activity and colour of probiotic yoghurt powder produced using a pilot‐scale spray dryer was investigated. Optimisation of spray drying conditions was achieved based on the desirability value. Results showed that inlet air temperature, drying air flow rate, feed flow rate and outlet air temperature of 150 °C, 478 m³/h, 2 L/h and 63.3 °C, respectively, were optimal conditions to produce powder that meets quality specifications and with a satisfactory% SR.     

Effect of seed moisture content on flaxseed (Linum usitatissimum L.) milling and milled product characteristics

BACKGROUND: Research was conducted to determine the effect of seed moisture content on flaxseed milling and milled product characteristics. Flaxseed with 55, 80, and 105 g kg^?1 moisture contents were milled on a centrifugal cutting mill (CCM) configured with a 0.475 and 9.5 kg min^?1 feed rate; a hammer mill configured with a blunt hammer face, 0.35 kg min^?1 feed rate, 3.1 mm screen, and 2,795 m min^?1 hammer tip speed; and a hammer mill configured with a sharp hammer face, 0.35 kg min^?1 feed rate, 2.7 mm screen, and 3,870 m min^?1 hammer tip speed. RESULTS: Fine‐particle fraction (≤600 µm) yield was greater from flaxseed with 55 than with 105 g kg^?1 moisture content. Surface lipid content correlated positively with fine‐particle yield (r = 0.82, P = 0.01). At each moisture level, the surface lipid extracted from the fine‐particle fraction was greater with 9.5 than 0.475 kg min^?1 configuration of CCM and tended to be greater with the blunt than with the sharp hammer configuration of the hammer mill. CONCLUSION: Results indicated that flaxseed was more difficult to mill to a fine particle size at high than at low moisture content regardless of the mill configuration. Enhanced lipid oxidation was not detected in freshly milled flaxseed. Copyright © 2009 Society of Chemical Industry     

Fast and isocratic HPLC-method for steviol glycosides analysis from Stevia rebaudiana leaves

A fast isocratic HPLC method for analysis of steviol glycosides from Stevia rebaudiana leaves was developed with a high selectivity for nine known steviol glycosides and low eluent consumption. The analytical method was performed on a Purospher^? STAR RP-18 endcapped 3???m Hibar^? RT 250-4.6 column at 50?°C with an eluent composition of water (65 vol.?%) and acetonitrile (35 vol.?%). With a flow rate of 1?mL?min^?1, nine known steviol glycosides were detected selectively after 15?min. Method validation for rebaudioside A showed a LOD of 0.0004?mg?mL^?1 and a LOQ of 0.0038?mg?mL^?1. Particularly with regard to moderate solubility, the method is linear up to a concentration of rebaudioside?A of 4.8?mg?mL^?1. The linear calibration curve was obtained with a coefficient of determination of 0.9997?±?0.0002 and a total error of 2.01?% RSD (n?=?12). The accuracy of the method was determined by the percentage mean recovery rate to 100.99?±?2.01?%. The intra-day precision was in a range of 0.12 to 1.96?%?RSD and the inter-day precision varies from 0.02 to 1.89?% RSD. Small changes in operating conditions like eluent composition (65?±?2 vol.?%), temperature (50?±?10?°C) or flow rate (1?±?0.2?mL?min^?1) do not affect the performance of the analytical method. The reliable and robust proposed HPLC method can be applied for quantification of steviol glycosides in Stevia rebaudiana Bertoni leaves in laboratories and quality control in industry.     

Optimisation of process parameters to develop nutritionally rich spray‐dried honey powder with vitamin C content and antioxidant properties

The aim of present research was to optimise the conditions to develop nutritionally rich honey powder using honey, whey protein concentrate (WPC), aonla (Emblica officinalis. Gaertn) and basil (Ocimum sanctum) extract with the help of co‐current spray drier. Response surface methodology was applied to study the effects of inlet temperature (160–180 °C), whey protein concentrate (25–35%), feed flow rate (0.08–0.13 mL s^?1), aonla extract (6–8%) and basil extract (6–8%) on product responses, viz. bulk density, hygroscopicity, antioxidant activity (AOA), total phenolic content (TPC) and vitamin C. Statistical analysis revealed that independent variables significantly affected all the responses. The results demonstrated that increasing inlet temperature lowered the bulk density, hygroscopicity, AOA, TPC and vitamin C, whereas addition of aonla extract and basil extract increased the AOA (82.73%), TPC (63.27%) and total vitamin C content (94.89%) as these functional compounds were encapsulated by WPC. Similarly, with increase in feed flow rate and WPC, there was increase and decrease in the bulk density and hygroscopicity, respectively. The recommended optimum spray‐drying conditions were inlet air temperature (170 °C), feed rate (0.11 mL s^?1), whey protein concentrate (35%), aonla (8%) and basil extract (6%).     

Effect of Temperature and Moisture Content on the Kinetics of Trypsin Inhibitor Activity, Protein in vitro Digestibility and Nitrogen Solubility of Cowpea Flour

Samples of finely ground cowpea flour containing 7.5%, 19.4% and 25.5% moisture were heated in sealed tubes at 100° 125° and 150°C for periods of 0.5 to 120 min. First order rate constants for losses of trypsin inhibitor activity and nitrogen solubility ranged from 1 × 10^?2 to 18 min^?1 and from 4 × 10^?2 to 8 min^?1 respectively. In vitro protein digestibility (IVD) increased, then decreased with heating as described by sequential first order kinetics. Rate constants for increase of IVD varied from 0.13 to 12 min^?1, while for decrease in IVD the range was 5 × 10^?5 to 3 × 10^?2 min^?1. Activation energies and relationships between In k and water activity were computed.     

Effect of spray‐drying parameters on the solubility and the bulk density of camel milk powder: A response surface methodology approach

Response surface methodology coupled with a Box–Behnken experimental design was used to investigate the effect of the air inlet drying temperature, the feed rate, and the fat content on the solubility and the bulk density of spray‐dried camel and cow milk powders. The response surface methodology analysis highlighted that milk fat content and feed rate were the most effective parameters affecting the solubility and the bulk density of cow and camel milk powders. Importantly, there was no significant interaction between the studied drying parameters and camel milk powder solubility or bulk density. Overall, camel milk powder exhibited a comparable solubility to that of cow milk powder with a higher bulk density.     

Effect of Process Parameters on Work Index, Milling Efficiency and Some Technological Properties of Yam Flour Using Attrition Mill

The effect of process parameters on work index, efficiency of milling, bulk density, swelling capacity and water absorption capacity of yam flour using attrition mill was studied. Independent variables were: moisture content (8, 12, 16, 20 and 24 % w.b.), speed (288, 346, 432, 576 and 864 rpm) and inlet opening (1,300, 2,600, 3,900, 5,200 and 6,500 mm²). The responses were work index, milling efficiency, bulk density, water absorption and swelling capacities of the flour. Work indexes for milling yam flour, meal and grit were found to be 0.25?±?0.13, 0.49?±?0.14 and 1.8?±?0.56, respectively. Flour fraction, bulk density, water absorption capacity and swelling capacity ranged from 42.2 to 56.6 %, 0.54 to 0.66 g/m³, 200 to 400 % and 13 to 23 ml, respectively. The treatments were found to influence the responses significantly (p?<?0.05). Optimum process condition was achieved at 12 % moisture content of feed, 506 rpm shaft speed and 5,200 mm² feed opening giving 19.1 % grit, 23.6 % meal and 54.2 % flour. The desirability of the optimisation process was 0.78. Validation of predicted optimal moisture content, worm shaft speed and feed inlet opening gave errors of 19, 14.4 and 6.1 % for grit, meal and flour, respectively.     

Spray Drying of Goat Milk Protein Hydrolysates with Angiotensin Converting Enzyme Inhibitory Activity

A goat milk hydrolysate was stabilized by spray drying using different inlet air temperatures (170–230 °C) and feed flow rates (4–12 mL/min) following a central composite experimental design. In order to evaluate the effect of operational conditions on process yield, powder properties (density, moisture, hygroscopicity, and solubility) as well as angiotensin converting enzyme (ACE) inhibitory activity, experimental data were analyzed by response surface methodology. Input variables showed a significant influence on yield, density, and moisture, while hygroscopicity, solubility, and ACE inhibitory activity were not affected. The dried hydrolysate presented an average IC₅₀ value of 273.13 μg/mL, which involved a loss of 25 % in ACE inhibitory activity with respect to the feed. The variations detected in the low molecular weight fractions of the dried hydrolysates could be responsible for the variations in ACE inhibitory activity.     

Preparation and characterization of kafirin‐quercetin film for packaging cod during cold storage

This study mainly evaluated the physical properties of kafirin‐quercetin (KQ) edible films and their application on the quality of cod fillets during cold storage. The results showed that the addition of quercetin significantly increased mechanical properties of KQ films, while decreased water vapor permeability, water solubility, and transparency. As quercetin was 0.4% (wt/vol), the film had the highest tensile strength (4.96 ± 1.23 MPa), the lowest water vapor permeability (1.08 ± 0.09 g·mm·m^?2·h·KPa^?1) and water solubility (22.02 ± 0.45%). Moreover, compared with the pure kafirin and polythylene films, KQ films could effectively inhibit the cod meat deterioration by restraining the growth of microorganisms and decreasing TVB‐N and TBARs. The KQ_0.4% film was the best to prolong the shelf life of cod fillets during cold storage. Therefore, KQ edible films could be used as a potential food packaging material to protect and retain the quality of aquatic products.     

慈姑粉的喷雾干燥工艺优化

以慈姑酶解液为原料,研究助干剂对慈姑出粉率的影响,在最优助干剂添加量的基础上,以出粉率、含水量及感官评分为评价指标,优化喷雾干燥过程中进风温度、进料流量和热空气流量参数,确定最佳干燥工艺条件。结果表明:在麦芽糊精添加量为40%,进风温度为180 ℃,进料流量为25%,热空气流量为36 m3/h时,慈姑出粉率最高,达48.51%±0.63%,比不添加助干剂的出粉率高出31.32%,含水量为4.86%±0.07%,慈姑粉为乳白色,粉粒细小均匀,风味浓厚,冲调性好,感官性状最佳。采用助干剂协同喷雾干燥技术制备慈姑粉能显著提高出粉率,改善慈姑粉品质。     

Postruminal protein supply upregulates hepatic lysine oxidation and ornithine transcarbamoylase in lactating dairy cattle

Metabolizable protein supply is a limiting factor for milk production in dairy cows, and the availability of AA is a function of the quantity of the metabolizable protein available and of hepatic AA catabolism. This study aimed to evaluate the effect of postruminal protein infusion on key genes for ureagenesis and AA catabolism. Six multiparous Holstein cows in early lactation were used in a replicated crossover design. Cows were fed a TMR and infused postruminally with either 0 or 600 g/d of milk protein isolate. Periods were 21 d long, consisting of 14 d of adjustment to surroundings, followed by 7 d of protein infusion. On the last day of each infusion, liver samples were collected for mRNA analysis and explant culture, milk samples were collected for mRNA analysis, and blood samples were collected for plasma metabolite analysis. Postruminal infusion of protein increased milk yield by 10.5%, milk fat yield by 12.5%, milk protein yield by 20%, milk lactose yield by 11%, and total solids yield by 15.5%. Postruminal infusion of protein increased milk urea N by 23.5%, blood urea N by 18.6%, and the abundance of hepatic ornithine transcarbamoylase mRNA by 52.8%. Postruminal infusion of protein did not alter the mRNA abundance of hepatic argininosuccinate synthase, α-aminoadipate semialdehyde synthase, cysteine sulfinic acid decarboxylase, or cystathionase. The abundance of RNA for milk proteins was unchanged with postruminal protein infusion. Metabolism of l-[U ¹⁴C] Lys to CO₂ was increased by 127% (0.143 vs. 0.063 ± 0.04 nmol product·mg tissue^?1·h^?1), and the metabolism of l-[U ¹⁴C] Ala to CO₂ increased by 40.5% (0.52 vs. 0.37 ± 0.06 nmol product·mg tissue^?1·h^?1) with postruminal protein infusion. The rate of l-[1-¹⁴C] Met oxidation did not differ. These data indicate increased ureagenesis matched by upregulation of nonessential AA catabolism and a disproportional increase in Lys oxidation in response to increased postruminal protein infusion.     

Protein quality of dried enzymatic hydrolysate from anchovy produced in a spouted bed of inert particles

The anchovy (Engraulis anchoita) is a pelagic fish and due to its abundance in South America shows a sustainable exploitation. The enzymatic hydrolysis of anchovy protein associated to the drying technique in spouted bed was analysed in order to obtain products with the best characteristics. The drying conditions were inlet air temperature, concentration and flow rate of suspension. The degree of hydrolysis of the anchovy suspension was of 3.8%, and its available lysine and specific antioxidant activity were of 86 g kg^?1_protein and 4.31 mm _DPPH kg^?1 min^?1, respectively. In spouted bed drying, the lowest reduction in available lysine (9%) and loss of specific antioxidant activity (8%) were found at 90 °C, and suspension concentration and flow rate of 65 g L^?1 and 200 mL h^?1, respectively. The dried product was characterised as a protein source of high biological value due to the essential amino acids profile.     

Elimination of dioxins in milk by dairy cows after the long-term intake of contaminated sugar beet pellets

ABSTRACT

Dried feed materials, such as sugar beet pellets, may be a source of high levels of PCDD/Fs. The studies followed up dioxin congener elimination from contaminated milk (5.02 ± 1.39 pg WHO PCDD/F-PCBs-TEQ g^?1 fat) up to 338 days after withdrawal of polluted feed ingredient (4.37 ± 0.25 ng PCDD/F/DL-PCBs-TEQ kg^?1 feed). The main objectives of the study were to estimate the length of the time needed to achieve an acceptable PCDD/F milk level as set by European Union law, to track the fate of the PCDD/F congeners, and to assess the potential risk for consumers associated with long-term consumption of contaminated milk. After approximately 200 days, the PCDD/F levels reached ML (2.5 pg WHO-TEQ g^?1 fat), then decreased to the action level after more than 300 days (1.75 pg WHO-TEQ g^?1 fat) for most of cows. The potential risk of PCDD/F/DL-PCBs intake was characterised by comparing the theoretically calculated weekly and monthly intakes with the toxicological reference values (TRVs). The dioxin intake for the average adult and high-milk consumers did not exceed half of any of the TRVs applied (TWI, PTMI). The consumption of milk by children in the amount recommended by nutritionists (500 ml day^–1) resulted in an exposure equal to 317% TWI and 275% PTMI.     

Functional and reconstitution properties of spray-dried sweetened yogurt powder as influenced by processing conditions

The influence of spray-drying conditions on functional and reconstitution properties of sweetened yogurt powder was studied. Twenty experiments with different spray-drying conditions (140–180°C inlet air temperature, 0.3–0.6 L/h feed rate and 500–1000 kPa atomization pressure) were performed according to central composite experimental design. Analysis of experimental data of solubility and dispersibility of yogurt powder revealed negative correlation with inlet air temperature and atomization pressure. Solubility of powder was significantly (p < 0.05) affected by feed rate. Wetting time of powder increased significantly (p < 0.001) with the increase of spray-drying temperature. The bulk, tapped, and particle densities were in the range of 344.8–475.7, 551.7–782.5, and 1187.5–1666.7 kg/m³, respectively. A significant quadratic effect (p < 0.001) of inlet air temperature and atomization pressure was observed on bulk density. Particle density increased with the increase in inlet air temperature and atomization pressure (p < 0.001). The results of the present investigation has the credible evidence to support that the processing conditions viz. inlet air temperature and atomization pressure decreased the water activity and flow property of the sweetened yogurt powder, whereas feed rate showed positive effect.     

Selective fractionation of cholesterol from whole milk powder: optimisation of supercritical process conditions

Supercritical fluid extraction (SCFE) of cholesterol from whole milk powder (WMP) was investigated in this study. The combined effects of temperature (40–80 °C) and pressure (150–250 bar) on the efficacy of cholesterol extraction (mg 100 g^?1), modifications in the fat content (FC) (%) and solubility index (SI) (%) of WMP were studied and optimised by the application of response surface methodology (RSM). Variations in the free fatty acids (FFAs) (mg oleic acid per 100 g of milk fat) and lightness value (L*) were also investigated after SCFE process. About 55.8% reduction in cholesterol was achieved at the optimised condition of 68 °C, 207 bar with 40 min static time and 2 h dynamic time at flow rate of 6 L min^?1. Extraction at the optimised conditions maximised the yield of cholesterol while retaining the FC, SI, FFA and L* at moderate limits of 23.7%, 85.1%, 7.7 mg per 100 g milk fat and 95.4, respectively.     

Lemon (Citrus limon, Burm.f.) essential oil enhances the trans-epidermal release of lipid-(A, E) and water-(B6, C) soluble vitamins from topical emulsions in reconstructed human epidermis

Topical bioavailability of lipid‐ and water‐soluble vitamins is a critical issue for protecting or anti‐ageing formulations. Using 17‐day‐old SkinEthic^® reconstructed human epidermis, we investigated (at 34°C) the role of lemon EO in enhancing the penetration of α‐tocopherol (E) and retinyl acetate (A), pyridoxine (B₆) and ascorbic acid (C), released from O/W or W/O emulsions. D‐limonene, α‐pinene and p‐cymene (65.9, 2.2 and 0.5%w/w of the oil) had skin permeability coefficients Ps (10^?3 cm h^?1) of 0.56 ± 0.03 (or 0.73 ± 0.02), 0.72 ± 0.05 (or 0.98 ± 0.05) and 0.84 ± 0.04 (or 1.14 ± 0.04), respectively, when incorporated in a W/O (or O/W) emulsion. Vitamins B6, C and A had Ps values of (3.0 ± 0.4) × 10^?3, (7.9 ± 0.6) × 10^?3 and (0.37 ± 0.02) × 10^?5 cm h^?1, respectively, and their flux through the skin was enhanced by a factor of 4.1, 3.4 and 5.8, respectively, in the presence of lemon EO. The penetration of vitamin E was nine‐fold enhanced. Lemon EO produced only reversible modification of TEWL, and it is a safe and effective penetration enhancer for topical administration of lipid‐ and water‐soluble vitamins.