Influence of processing temperature on production of red beetroot powder as a natural red colorant using foam-mat drying: Experimental and modeling study.

With high medicinal and nutritional value, red beetroot powder is utilized as a natural pigment and functional additive in various food industries. In this investigation, red beetroot powder was produced using foam-mat drying, and the effect of drying temperature on quality attributes was evaluated. Computer simulation was also performed to assess the impact of temperature on uniformity of moisture loss and temperature during drying. Temperature variations did not exert a significant impact on water solubility and total color difference of the powders. Images obtained from field emission scanning electron microscopy illustrated that with increasing temperature, wrinkling, cracking, and roughness of the powder particles reduced because of the formation of smooth and hard crusts on the particles' surface. Predicted moisture content values were in good agreement with measured data. The results of this study could be used to optimize foam-mat drying of red beetroot to produce functional powders with suitable physicochemical and microstructural characteristics.

Effect of combined convective hot air and far-infrared radiation on physic-chemical aspects of black raspberry powder produced by foam mat method.

In recent years the use of hybrid drying methods has been noticed because of the improvement of the dried products quality. The effect of infrared (IR) power (0, 400, 600, and 800 W) in combination with convective hot air (60 °C, 3 m/s) on the quality properties of black raspberry pulp during foam mat drying was investigated in this study. According to the findings, increasing the IR power, (IR-CHA) had no effect on the moisture content, moisture ratio, or drying rate of the product; however, the effective moisture diffusion coefficient (Deff) was significantly increased. The effect of IR power on the physicochemical properties of black raspberry powder revealed that combining infrared with convective hot air (IR-CHA) improved the powder's flowability and total polyphenol content while decreasing its moisture content (p < 0.05). Furthermore, FESEM images revealed that the increase in IR power resulted in particles with smooth surfaces.

Investigation of microwave application time with constant pulse ratio on drying of zucchini.

Since nonuniform drying in the continuous microwave harms the safety and quality of dried food materials, a significant quality improvement can be achieved by controlling the application time of the microwave. This study aimed to investigate the influence of microwave application time and power at a constant pulse ratio during the drying of zucchini on different product characteristics. The samples were first exposed to microwaves with powers of 360, 600, and 900 W alternately for 10, 30, and 50 s. After drying with intermittent microwaves, the process was continued using the hot-air drying. Increasing the microwave application time and power caused a significant reduction in the total process time. The minimum drying time was obtained at 900 W and 50 s (259.44 min). Deff increased significantly by 24.4% and 34.1% with increasing application time and power, respectively. The highest shrinkage and bulk density were observed in the samples dried at 360 W and 10 s due to a longer total process time than the other treatments. Rehydration increased by 10.3% and 14.7% with increasing application time and power, respectively. A 33% decrease in energy consumption was noticed in the 900 W-50 s treatment compared to the 360 W-10 s treatment. Moreover, with increasing microwave application time and power, the lightness of the dried product decreased, and the total color difference increased. In summary, the 900 W power and 50 s application time produced a better-dried product than the other treatments considering different quantitative and qualitative properties. The results of this research can be used in the food industry to dry products using microwave and hot air to control and improve their quality.

Electrospun nanofibers fabricated by natural biopolymers for intelligent food packaging.

An "intelligent" or smart packaging is able to continuously monitor physicochemical and/or biological variations of packaged food materials, providing real-time information concerning their quality, maturity, and safety. Electrospun nanofiber (ENF) structures, nowadays, reckon as versatile biomaterial platforms in designing intelligent packaging (IP) systems. Natural biopolymer-based ENF traits, for example, surface chemistry, rate of degradation, fiber diameter, and degree of alignment, facilitate the development of unique, tunable IP, enhancing food quality, and safety. In this review, after a brief overview of the electrospinning process, we review food IP systems, which can be utilized to detect variations in food features, for example, those based on alterations in temperature, O2 level, time, humidity, pH, or microbial contamination. Different intelligent approaches that are applicable in engineering IP materials are then highlighted, that is, indicators, data carriers, and sensors. The latest research on the application of ENFs made with natural biopolymers in food IP and their performance on different packaged food types (i.e. meat, fruits and vegetables, dairy products, etc.) are underlined. Finally, the challenges and outlook of these systems in the food industry are discussed.

Photo-catalytic and biotic degradation of polystyrene packaging film: Effect of zinc oxide photocatalyst nanoparticles and nanoclay.

Synergistic effect of zinc oxide nanoparticles (ZnO-NPs) as photocatalyst and organonanoclay (ONC) as biodegradable promoter on the degradation of polystyrene (PS) film was investigated. The films were exposed to ultraviolet irradiation under ambient air at room temperature for photo-catalytic degradation and then submitted to biodegradation test in soil using respirometric procedure. Fourier-transform infrared and ultraviolet-visible spectroscopy, thermogravimetric analysis, colorimeter technique, contact angle measurement, and the carbon dioxide evolution results showed higher photo- and biodegradation efficiency of PS-ONC-ZnO nanocomposite compared to the neat PS, PS-ONC and PS-ZnO nanocomposites. Thermal stability, optical band gap, and water contact angle of photo-degraded PS-ONC-ZnO nanocomposite decreased by 11.37, 18.33 and 63.99%, respectively, while that of PS film was only 6.20, 6.44 and 5.84%, respectively. The photo-degraded PS-ONC-ZnO and PS-ZnO film indicated a biodegradation percentage value of 3.3 and 2.1%, respectively, over 16 weeks of incubation in soil. The possible degradation mechanism of nanocomposites was briefly discussed.

Thermal and antimicrobial properties of chitosan-nanocellulose films for extending shelf life of ground meat.

Chitosan-nanocellulose biocomposites were prepared from chitosan having molecular weight of 600-800 kDa, nanocellulose with 20-50 nm diameters and various levels of 30, 60 and 90% (v/wCHT) for glycerol. Agitation and sonication were used to facilitate even dispersion of particles in the polymer matrix. The nanocomposites were examined by differential scanning calorimetry, X-ray diffraction and agar disc diffusion tests; finally, the film was applied on the surface of ground meat to evaluate its performance in real terms. Chitosan-nanocellulose nanocomposites showed high Tg range of 115-124°C and were able to keep their solid state until the temperature (Tm) range of 97-99°C. XRD photographs revealed that nanocellulose peak completely disappeared after their addition to chitosan context. Agar disc diffusion method proved that the nancomposite had inhibitory effects against both gram-positive (S. aureus) and gram-negative (E. coli and S. enteritidis) bacteria through its contact area. Application of chitosan-nanocellulose nanocomposite on the ground meat decreased lactic acid bacteria population compared with nylon packaged samples up to 1.3 and 3.1 logarithmic cycles at 3 and 25°C after 6 days of storage, respectively.

Optimization of physical and mechanical properties for chitosan-nanocellulose biocomposites.

Chitosan (CHT) is a biodegradable compound and has excellent performance in forming films; on the other hand, nanocellulose (NCL) crystals have low densities and are less expensive than other nanofillers. A novel and simple method was applied to develop CHT-NCL nanocomposite (NCP) from CHT powder of high molecular weight and NCL particles having two dimensions in nanoscale; a rotor stator and an ultrasound device were used to separate different nanolayers from each other and facilitate their dispersion into polymer matrix. The optimized NCP indicated superior mechanical properties compared with some synthetic films; approximate values of 47% elongation-at-break, 245MPa tensile strength and 4430MPa Young's modulus were achieved. Water vapour permeability (WVP) value of the NCP was at optimal level of 0.23×10(-11) (g/msPa) which was much less than the most biofilms' WVP values. FESEM analyses revealed that high concentrations of CHT and NCL composed inter-connected structures justifying high elongation capability of CHT-NCL NCP.