Mladen Brnčić

Ultrasound assisted extraction and characterization of pectin from tomato waste

Pectin was extracted from tomato waste using two different extraction methods to assess its potential utilization as an alternative source of commercial pectin production. Tomato waste was treated with ammonium oxalate/oxalic acid by conventional extraction (CE), under reflux and ultrasound assisted extraction (UAE) at 37 kHz and temperatures of 60 °C and 80 °C. The pectin obtained from these methods was analysed and compared in terms of yield, chemical properties and structure. Among examined methods, CE at 60 °C resulted with the highest yield, but UAE during 15 min of sonication produced the pectin of better quality (anhydrouronic acid, methoxy and calcium pectate contents and degree of esterification). NMR and FTIR spectroscopy of isolated pectins revealed predominantly esterified structure, irrespective of extraction conditions. The comparison of the pectin yields obtained after extraction at 80 °C, indicate that similar values were found at times of 24h and 15 min for CE and UAE, respectively. According to obtained results it can be concluded that main advantage of UAE is considerable shortening of extraction procedure with strong emphasis on environmental friendly processing approach. Therefore, these results suggested that UAE could be used as an efficient technique for the extraction of pectin from tomato waste and by-products.

Physical, bioactive and sensory quality parameters of reduced sugar chocolates formulated with natural sweeteners as sucrose alternatives

In this study, sugar alcohols, dietary fibers, syrups and natural sweeteners were used as sucrose alternatives in the production of reduced sugar chocolates (50% of cocoa parts) with enhanced bioactive profile. Formulated chocolates were evaluated for their physical (particle size distribution, texture) and sensory properties, sugar composition, polyphenolic compounds content and antioxidant capacity. All produced reduced sugar chocolates ensured >20% lower calorific value than conventional chocolate (prepared with sucrose). Formulated chocolates containing stevia leaves and peppermint exhibited the best sensory properties (especially with regard to mouthfeel, sweetness and herbal aroma), as well as the highest polyphenolic content and antioxidant capacity. Particle size and hardness of chocolates increased in comparison to conventional chocolate, in particular when the combination of fructose and isomalt or lactitol was used. The bioactive profile of produced chocolates was enriched with phenolic acids, flavone (luteolin and apigenin) and flavonol (quercetin) derivatives, which were not identified in control chocolate.

Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain

The enormous quantity of food wastes discarded annually forces a look into alternatives for this interesting feedstock. Thus, food bio-waste valorisation is one of the current imperatives of society. This review is the most comprehensive overview of currently existing technologies and processes in this field. It tackles classical and innovative physical, physico-chemical and chemical methods of food waste pre-treatment and extraction for the recovery of added value compounds and detection by modern technologies and is an outcome of the COST Action EUBIS, TD1203 Food Waste Valorisation for Sustainable Chemicals, Materials and Fuels.

Optimization of Ultrasound Assisted Extraction of Functional Ingredients from Stevia Rebaudiana Bertoni Leaves

Abstract The aim of the present study was to reveal an effective extraction procedure for maximization of the yield of steviol glycosides and total phenolic compounds as well as antioxidant activity in stevia extracts. Ultrasound assisted extraction was compared with conventional solvent extraction. The examined solvents were water (100°C/24 h) and 70% ethanol (at 70°C for 30 min). Qualitative and quantitative analyses of steviol glycosides in the extracts obtained were performed using high performance liquid chromatography. Total phenolic compounds, flavonoids, and radical scavenging capacity by 2, 2-azino-di-3-ethylbenzothialozine- sulphonic acid) assay were also determined. The highest content of steviol glycosides, total phenolic compounds, and flavonoids in stevia extracts were obtained when ultrasound assisted extraction was used. The antioxidant activity of the extracts was correlated with the total amount of phenolic compounds. The results indicated that the examined sonication parameters represented as the probe diameter (7 and 22 mm) and treatment time (2, 4, 6, 8, and 10 min) significantly contributed to the yield of steviol glycosides, total phenolic compounds, and flavonoids. The optimum conditions for the maximum yield of steviol glycosides, total phenolic compounds, and flavonoids were as follows: extraction time 10 min, probe diameter 22 mm, and temperature 81.2°C.

Effect of twin-screw extrusion parameters on mechanical hardness of direct-expanded extrudates

Mechanical properties of cereal (starch-based) extrudates are perceived by the final consumer as criteria of quality. We investigate one of the important characteristics of extrudates, mechanical hardness, which is one of the main texture parameters. Texture quality has an influence on taste sensory evaluation, and thus on the acceptability of the product. Characteristics that have great influence on acceptability are crispness, elasticity, hardness and softness.These attributes are narrowly related to, and affected by, the process parameters. A 2-level-4-factor factorial experimental design was used to investigate the influence of temperature of expansion, screw speed, feed moisture content and feed rate, and their interactions, on the mechanical hardness of extrudates. Feed moisture content, screw speed and temperature are found to influence, while feed rate does not have significant effect on extrudate hardness.Mechanical properties of specimens were measured by means of compression testing, based on the concept of nominal stress, using a universal testing machine and special grips that were constructed for this purpose.

Tribomechanical micronization and activation of whey protein concentrate and zeolite

Tribomechanics is a part of physics that is concerned with the study of phenomena that appear during milling under dynamic conditions. Tribomechanical micronization and activation (TMA) of whey protein concentrates (WPC) and zeolites (type clinoptilolite) were carried out. Samples of powdered WPC and zeolite were treated with the laboratory TMA equipment. The treatment was carried out at two various rotor speeds: 16,000 and 22,000 r.p.m. at ambient temperature. Analyses of the particle size and distribution as well as the specific area and scanning electron microscopy were carried out on the powdered WPC and zeolite, before and after the TMA treatment. Suspensions of the WPC and zeolite were treated with ultrasound, just before determining the particle size distribution, at 50 kHz. The results showed that tribomechanical treatment causes significant decrease in particle size, change in particle size distribution and increase in specific area of WPC and zeolite. These changes of the treated materials depend on the type of the material, the level of inserting particles, the planned angle of the impact, internal rubbing and the planned number of impacts. The effects found became stronger as the rotor speed of the TMA equipment increased (16,000 to 22,000 rpm). Ultrasonic treatment of suspension of tribomechanically treated WPC resulted infurther breakdown of partly damaged protein globules as proved with the statistic analyses. No further changes in their granulometric composition were caused by ultrasonic treatment of a suspension of tribomechanically treated zeolite.

Sevelamer Restores Bone Volume and Improves Bone Microarchitecture and Strength in Aged Ovariectomized Rats

Sevelamer hydrochloride, a noncalcium phosphate binder, has been shown to reduce coronary artery and aortic calcification, and to improve trabecular bone mineral density in hemodialysis patients with chronic kidney disease. Here, we examined whether sevelamer given orally for 12 wk with normal food could restore bone volume (BV) and strength in aged ovariectomized (OVX) rats starting at 4 wk after OVX. Dual-energy x-ray absorptiometry, microcomputerized tomography, and bone histomorphometry analyses showed that OVX animals receiving sevelamer had increased trabecular BV (51%), trabecular number (43%), trabecular thickness (9%), cortical thickness (16%), mineral apposition rate (103%), bone formation rate (25%), and enhanced cortical and trabecular bone mechanical strength as compared with OVX rats. Sevelamer decreased collagen C telopeptide, increased osteocalcin levels, and decreased phosphate and magnesium levels without affecting calcium levels in the blood. Although sevelamer was not absorbed systemically, it stimulated osteoblast differentiation in BM-derived mesenchymal stem cell cultures, as evaluated by alkaline phosphatase positive colony-forming units, and inhibited recombinant human soluble receptor activator of nuclear factor-kappaB ligand-induced osteoclast differentiation, as evaluated by tartrate-resistant acid phosphatase positive cells in bone mineral-hematopoietic stem cell cultures. Surface enhanced laser desorption/ionization time-of-flight mass spectrometry analysis revealed that 69 proteins were differently expressed after OVX, of which 30% (20 of 69) were reversed to sham activity after sevelamer intake. PTH, fibroblast growth factor-23, and cytokine profile in serum were not significantly changed. Together, these results suggest that sevelamer in food increases the BV and improves biomechanical properties of bone in OVX rats.

Reducing Fat Globules Particle-Size in Goat Milk : Ultrasound and High Hydrostatic Pressures Approach

Innovative and eco-friendly food technologies in practical usage today like Ultrasound (US) and High Hydrostatic Pressures (HHP) are feasible to adequately maintain various food properties while processed, such as texture, sensorial and organoleptic characteristics, and microbiological issues as well. Benchmarked attribute of the mentioned approach lies in the ability of US and HHP to control and withhold both temperature and treatment duration. While temperature could be controlled within room ambient, treatment time is mostly below 30 minutes. US and HHP treatment were performed as separate treatments in order to obtain better homogenization. Goat milk was exposed to ultrasonic propagation up to 100 W of nominal power and high pressures up to 600 MPa. Maximum treatment time was 9 minutes. Ultrasonic homogenization indicates enhanced homogeneity of fat globules while high pressure process parameters have a significant influence on the observed mean particle diameter (fat globules). Improved stability and quality of emulsions (goat milk) was obtained by both applied processes. Statistical analysis indicated the influence of process parameters on fat globule size distribution between 0.3 – 4 µm and variance lower than 0.6.

Comparison of Conventional and Ultrasound-assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from Sage (Salvia officinalis L.)

Sage (Salvia officinalis L.) is a popular herb which is native to the Mediterranean region and cultivated worldwide. Sage is an important source of antioxidants used as preservatives and has wider implications for the dietary intake of natural antioxidants.1,2 This antioxidant effect has been attributed to the main phenolic components, caffeic acid dimer – rosmarinic acid1 and flavonoids, being mostly present as flavones and their glycosides. Flavone glycosides are apparently common in sage, and most of them are flavones 7-glycosides represented by apigenin and luteolin 7-glucoside and their corresponding 3and 7-glucuronides.2 In the last few decades, research regarding the extraction of phenolic compounds found in plants have attracted special interest regarding their application in the food industry. Extraction is a very important step in the isolation, identification, and use of polyphenols.3 The conventional extraction methods, which have been employed for decades, require prolonged extraction times and relatively larger quantities of solvent.4,5 Therefore, various novel extraction techniques have been developed for the extraction of bioactive compounds from herbs, including ultrasound-assisted extraction,6–8 microwave-assisted extraction,9 supercritical fluid extraction.10 Ultrasound-assisted extraction is an upcoming extraction technique that can offer high reproducibility in shorter time, higher yields of bioactive compounds, simplified manipulation, decreased temperature during processing, reduced solvent consumption, and lower energy input.11–13 In our previous paper,5 the influence of solvent polarity and composition, time and temperature of conventional extraction on mass fraction of polyphenols from sage were researched. The mixtures of ethanol and water are possibly the most suitable solvents for the extraction of sage due to different polarities of the active constituents, and acceptability of this solvent system for human consumption.4,5 Albu et al.3 and Sališova et al.14 have investigated the difference in the application of conventional extraction and ultrasonic-assisted extraction on the concentration of biologically active compounds in sage. They concluded that the content of biologically active compounds is approximately 60 % higher under the influence of ultrasound. Rosmarinic acid is the more active of these antioxidants, but it is relatively easily degraded in solvent and the rate of degradation is solvent-dependant.6 The ultrasonic-assisted extraction has been widely used for obtaining polyphenols from plants using ethanol, mixture of ethanol/waComparison of Conventional and Ultrasound-assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from Sage (Salvia officinalis L.)

Chapter 11 – Emerging extraction

Traditional extraction methods include usually high temperature treatment (more than 100°C) with the subsequent risk of thermal denaturation or transformation of the target molecules. Moreover, these techniques are very time-consuming and require relatively large quantities of solvents. On the other hand, the use of environmentally friendly technologies has led researchers and the food industry to develop new alternative processes that can extract valuable compounds from different sources and food wastes of different origin. This chapter describes the potential use of emerging technologies such as ultrasound-assisted extraction (UAE), laser ablation, pulsed electric fields (PEF), high voltage electrical discharge (HVED), and membrane-assisted extraction. The latest methodologies comply with the concepts of green chemistry and sustainability within the food industry.