Summary
Pomegranate (Punica granatum) bioactive compounds (polyphenols and anthocyanins) of juice (PJ) and ethanolic extracts (PE) were encapsulated with maltodextrin (MD) or soybean protein isolates (SPI) by spray drying using a 22 statistical factorial design for each systems studied (PJ–MD, PJ–SPI, PE–MD and PE–SPI) considering the proportion of coating material and the inlet temperature as independent variables. The stability of the bioactive compounds microcapsules powders obtained under optimal conditions for each system was studied at 60 °C in oven for 56 days. The polyphenols encapsulating efficiency was significantly better in SPI matrix whereas for anthocyanins was in MD matrix. By the other hand, during the storage, the MD microcapsules provided a significant greater protective effect on the polyphenols and anthocyanins than SPI, as was shown by the lower degradation rate constants. When the microcapsules were added to yogurt the stability of the bioactive compounds followed a similar behaviour to those without encapsulation, except for PE–MD.

Encapsulation of polyphenols and anthocyanins from pomegranate (Punica granatum) by spray drying

Summary Pomegranate (Punica granatum) bioactive compounds (polyphenols and anthocyanins) of juice (PJ) and ethanolic extracts (PE) were encapsulated with maltodextrin (MD) or soybean protein isolates (SPI) by spray drying using a 2 2 statistical factorial design for each systems studied (PJ–MD, PJ–SPI, PE–MD and PE–SPI) considering the proportion of coating material and the inlet temperature as independent variables. The stability of the bioactive compounds microcapsules powders obtained under optimal conditions for each system was studied at 60 � C in oven for 56 days. The polyphenols encapsulating efficiency was significantly better in SPI matrix whereas for anthocyanins was in MD matrix. By the other hand, during the storage, the MD microcapsules provided a significant greater protective effect on the polyphenols and anthocyanins than SPI, as was shown by the lower degradation rate constants. When the microcapsules were added to yogurt the stability of the bioactive compounds followed a similar behaviour to those without encapsulation, except for PE–MD.

Original article Encapsulation of polyphenols and anthocyanins from pomegranate (Punica granatum) by spray drying

An Introduction to Plant Biochemistry By Dr. Catherine Cassels Steele. Second edition, revised. Pp. viii + 346. (London: G. Bell and Sons, Ltd., 1949.) 22s. 6d.

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Biochemistry of Plants

Pomegranate juice was diluted to 12° Brix and carriers (maltodextrin, gum Arabic, waxy starch) were added with varying concentrations of cellulose before being reduced to powder by spray drying. All carrier concentrations improved dryer yield, with gum Arabic being the most effective. The bulk density of the powder decreased when higher carrier concentrations were used. As cellulose concentration increased in solution, the solubility of the final product decreased. The optical properties of the powder were affected by the type and concentration of the carrier; powders produced with gum Arabic showed the greatest color change. Adding a carrier increased the Tg of the powder and its storage stability. Variation in the anthocyanin may be related to the type of carrier agent and its behavior during spray drying.

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Effect of carrier type and spray drying on the physicochemical properties of powdered and reconstituted pomegranate juice (Punica Granatum L.)

In this review paper, several aspects of fruit juice microbiology, from past to future perspectives, are considered. An overview of the most relevant outbreaks involving foodborne pathogens and spoilage microorganisms associated with fruit juices is provided. One of the sections provides data on the sources of fruit juice contamination, followed by perspectives on preservation methods. Furthermore, considerations on the role of international guidelines about exotic fruit juices in respect to public health, and of the microbiological status of fruit juices used as food/beverage ingredients are discussed. Issues and challenges highlight how the microbiology of fruit juices has evolved over the years, when aspects of stability or microbiological safety are under consideration.

Review: Microbiological quality and safety of fruit juices--past, present and future perspectives.

Effect of temperature, concentration, and pressure on the viscosity of pomegranate and pear juice concentrates

The thermal conductivity (k) of four fruit juices (peach, raspberry, cherry and plum) was measured using a coaxial-cylinder (steady-state) technique. Measurements were made in the temperature range from 20 to 120C and a range of concentration between 9.8 and 60.0°Brix. The total uncertainties of the k and temperature measurements were less than 2% and 0.03C, respectively. The reliability and accuracy of the experimental methodology for fruit juices was confirmed with measurements on pure water. The experimental and calculated values of k of pure water showed excellent agreement within their experimental uncertainty. The effect of temperature and concentration on the k of peach, raspberry, cherry and plum juices was evaluated. The predictive capability of various polynomial models was established.

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Thermal conductivity of peach, raspberry, cherry and plum juices as a function of temperature and concentration

Summary
Viscosities of two fruit (lemon and tangerine) juices have been measured with a capillary flow technique. Measurements were made in the temperature range from 303 to 393 K. The range of concentration was between 15 and 40 °Brix for tangerine juice and between 17 and 45 °Brix for the lemon juice. The total uncertainty of viscosity and temperature measurements was estimated to be <0.5% at low concentrations and up to 1.5% at high concentrations and 0.025 K, respectively. The effect of temperature and concentration on viscosity of tangerine and lemon juices was study. The measured values of the viscosity were used to calculate the temperature, (∂ ln η/∂T)x, and concentration, (∂ ln η/∂x)T, coefficients for each juice. The Arrhenius type correlation equations for viscosity were used to represent the temperature dependence of viscosity. The values of the Arrhenius equation parameters (flow activation energy, Ea, and η∞) were calculated for the measured viscosities of tangerine and lemon juices as a function of concentration. Different theoretical models for the viscosity of fruit juices were stringently tested with new accurate measurements on tangerine and lemon juices. The predictive capability of the various models was studied. The concentration and temperature dependence behavior of the viscosity of tangerine and lemon juices are discussed in light of the various theoretical models for viscosity of fruit juices. The applicability and predictive capability of the models used previously for aqueous solutions to represent the effect of temperature and concentration on viscosity of fruit juices was also studied. New model was developed to represent the combined effect of temperature and concentration on the viscosity of the juices. The average absolute deviation between measured and calculated values from this correlation equation for the viscosity was 0.8% and 2.1% for tangerine and lemon juices, respectively.

Viscosity of tangerine and lemon juices as a function of temperature and concentration

Density of seven fruit juices (melon, plum, peach, black currants, cherry-plum, pear, and tangerine) have been measured at temperatures from 283 to 403 K and at pressures from 0.1 to 10 MPa for the concentrations of soluble solids from 10.7 to 70°Brix. Measurements were made with a hydrostatic weighing technique. The uncertainty of the density measurements was estimated to be less than 0.075%. The effect of temperature, pressure, and concentration on the fruit juice density was studied. The applicability and predictive capability of the various models for the density of fruit juices were studied. Various polynomials, power, exponential, logarithmic, and their combinations correlation models were used to represent the combined effect of temperature and concentration on the density. Models which represent the density of juice relative to pure water density were considered.

Pressure- and Temperature-Dependent Density Change of Juices During Concentration

The thermal conductivity of 4 fruit (pear, sweet-cherry, apricot, and cherry-plum) juices was measured with a coaxial-cylinder (steady-state) technique. Measurements were made, temperature range 20 to 120 °C, at concentrations between 12.2 and 50 °Brix. The uncertainty of the thermal conductivity measurements was estimated to be less than 2%. A semitheoretical method for the prediction of thermal conductivity of juices was proposed. It was found that the prediction Model IV, λ (T, x)/λ (T0, x) = (T/T0)n, where λ is the thermal conductivity, x is the concentration, and T is the temperature, developed in this work can be adopted with satisfaction. The thermal conductivity of juices can be predicted just by knowing the thermal conductivity λ0 at a reference temperature T0.

Mikail A. Magerramov

Papers

Effect of temperature, concentration, and pressure on the viscosity of pomegranate and pear juice concentrates

Thermal conductivity of peach, raspberry, cherry and plum juices as a function of temperature and concentration

Viscosity of tangerine and lemon juices as a function of temperature and concentration

Pressure- and Temperature-Dependent Density Change of Juices During Concentration

Thermal conductivity of pear, sweet-cherry, apricot, and cherry-plum juices as a function of temperature and concentration