Shekhar U. Kadam

Application of Novel Extraction Technologies for Bioactives from Marine Algae

Marine algae are a rich source of bioactive compounds. This paper outlines the main bioactive compounds in marine algae and recent advances in novel technologies for extracting them. Novel extraction technologies reviewed include enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, supercritical fluid extraction, and pressurized liquid extraction. These technologies are reviewed with respect to principles, benefits, and potential applications for marine algal bioactives. Advantages of novel technologies include higher yield, reduced treatment time, and lower cost compared to traditional solvent extraction techniques. Moreover, different combinations of novel techniques used for extraction and technologies suitable for thermolabile compounds are identified. The limitations of and challenges to employing these novel extraction technologies in industry are also highlighted.

Laminarin from Irish Brown Seaweeds Ascophyllum nodosum and Laminaria hyperborea: Ultrasound Assisted Extraction, Characterization and Bioactivity

Ultrasound assisted extraction (UAE), purification, characterization and antioxidant activity of laminarin from Irish brown seaweeds Ascophyllum nodosum and Laminarina hyperborea were investigated. UAE was carried out using 60% ultrasonic power amplitude and 0.1 M hydrochloric acid for 15 min. Separately, solid-liquid extraction was carried in an orbital shaker using 0.1 M hydrochloric acid at 70 °C for 2.5 h. UAE with hydrochloric acid resulted in the highest concentration of laminarin, 5.82% and 6.24% on dry weight basis from A. nodosum and L. hyperborea, respectively. Purification of all extracts was carried out using molecular weight cut off dialysis at 10 kDa. Characterization of the laminarin fraction was carried out using matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Antioxidant activity of A. nodosum and L. hyperborea extracts had 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition levels of 93.23% and 87.57%, respectively. Moreover, these extracts have shown inihibition of bacterial growth of Staphylcoccus aureus, Listeria monocytogenes, Escherichia coli and Salmonella typhimurium.

Effect of ultrasound pre-treatment on the drying kinetics of brown seaweed Ascophyllum nodosum

The effect of ultrasound pre-treatment on the drying kinetics of brown seaweed Ascophyllum nodosum under hot-air convective drying was investigated. Pretreatments were carried out at ultrasound intensity levels ranging from 7.00 to 75.78 Wcm(-2) for 10 min using an ultrasonic probe system. It was observed that ultrasound pre-treatments reduced the drying time required. The shortest drying times were obtained from samples pre-treated at 75.78 Wcm(-2). The fit quality of 6 thin-layer drying models was also evaluated using the determination of coefficient (R(2)), root means square error (RMSE), AIC (Akaike information criterion) and BIC (Bayesian information criterion). Drying kinetics were modelled using the Newton, Henderson and Pabis, Page, Wang and Singh, Midilli et al. and Weibull models. The Newton, Wang and Singh, and Midilli et al. models showed the best fit to the experimental drying data. Color of ultrasound pretreated dried seaweed samples were lighter compared to control samples. It was concluded that ultrasound pretreatment can be effectively used to reduce the energy cost and drying time for drying of A. nodosum.

Power ultrasound as a pretreatment to convective drying of mulberry (Morus alba L.) leaves: Impact on drying kinetics and selected quality properties

The effect of ultrasound pretreatment prior to convective drying on drying kinetics and selected quality properties of mulberry leaves was investigated in this study. Ultrasound pretreatment was carried out at 25.2-117.6 W/L for 5-15 min in a continuous mode. After sonication, mulberry leaves were dried in a hot-air convective dryer at 60 °C. The results revealed that ultrasound pretreatment not only affected the weight of mulberry leaves, it also enhanced the convective drying kinetics and reduced total energy consumption. The drying kinetics was modeled using a diffusion model considering external resistance and effective diffusion coefficient De and mass transfer coefficient hm were identified. Both De and hm during convective drying increased with the increase of acoustic energy density (AED) and ultrasound duration. However, De and hm increased slowly at high AED levels. Furthermore, ultrasound pretreatment had a more profound influence on internal mass transfer resistance than on external mass transfer resistance during drying according to Sherwood numbers. Regarding the quality properties, the color, antioxidant activity and contents of several bioactive compounds of dried mulberry leaves pretreated by ultrasound at 63.0 W/L for 10 min were similar to that of mulberry leaves without any pretreatments. Overall, ultrasound pretreatment is effective to shorten the subsequent drying time of mulberry leaves without damaging the quality of final product.

Effect of Ultrasound Pretreatment on the Extraction Kinetics of Bioactives from Brown Seaweed (Ascophyllum nodosum)

The work investigates the application of ultrasound for improved extraction of bioactive compounds namely total phenolics, fucose, and uronic acid from brown seaweed (Ascophyllum nodosum). Key process parameters of ultrasonic intensity (UI), extraction time, and solvent type were investigated to optimize extraction yields. The maximum yields on dry basis (db) of total phenolics, fucose, and uronic acid were 82.70 mg GAE/gdb, 135.76 mg/gdb, and 197.19 mg/gdb, respectively. Maximum bioactive yields were obtained using 0.03 M HCl as solvent at an UI of 75.78 W cm−2. Extraction kinetics over a 22 hour period were successfully modelled using Peleg’s model. This extraction kinetic study demonstrates that ultrasound pretreatment can significantly enhance extraction of bioactives from brown seaweed.

Extraction and characterization of protein from Irish brown seaweed Ascophyllum nodosum.

This study investigates traditional and non-conventional methods of extraction of protein from Irish brown seaweed A. nodosum. Acid, alkali, combined acid-alkali with and without ultrasound pretreatment were investigated for extraction of protein from A. nodosum. Molecular weight of protein was determined using high performance size exclusion chromatography and amino acid profiling was carried out using an amino acid analyzer. Combination of first acid and then alkali extraction was found to be the most efficient method of extraction among all methods investigated (59% of recovery); followed by single step of alkali extraction assisted with ultrasound (68.4μm) which was able to extract 57% of total protein. Alkaline extraction was shown to yield the best protein/algae liquefaction ratio (1.28). This can be attributed to the release of polysaccharide complexes first by acid and then solubilization of proteins by alkali solvent. The molecular weight of extracted protein was found to be relatively low, in the range of 2-4kDa average MW. The alkali method of extraction was found to be optimum for extraction of amino acids from A. nodosum.

Extraction of biomolecules from seaweeds

Abstract Seaweeds are an excellent source of phenolics, polysaccharides, proteins, peptides, and pigments. The seaweed extraction technologies currently employed are energy intensive and require extended extraction times. Thus, there is a need to develop efficient and environmentally friendly technologies for biomolecule extraction from seaweeds. Recently, novel extraction technologies such as enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, supercritical fluid extraction, and pressurized liquid extraction have been demonstrated to have potential application for extraction of biomolecules from seaweeds. Advantages of these novel technologies include increased yield and reduced extraction time as compared to traditional solvent extraction techniques. This chapter outlines recent advances in novel technologies for seaweed extraction applications.

Processing of seaweeds

Seaweeds are an important marine bioresource widely utilized in pharmaceutical, nutritional, and cosmetic products. Although the harvesting of seaweeds is mainly carried out by manual methods, mechanical methods are routinely employed for large-scale operations. Collected seaweeds are dried by direct solar and hot air drying methods. Different pretreatment techniques, such as ultrasonic and microwave, have been used to enhance drying rates. This chapter outlines the various seaweed processing stages from harvesting, storage, drying, and extraction to subsequent product preparation.

Improved thermal processing for food texture modification

Abstract This chapter reviews the mechanisms governing textural changes of thermally treated food products including pectin solubilization, loss of turgor, starch gelatinization and protein denaturation. Also, various pre-treatments to improve the texture of thermally processed foods, including blanching/preheating, high pressure and addition of chemicals such as calcium ions and phenolics are outlined. Thermal processing variables can have desirable or undesirable influences on food texture. Food processing methods of high-temperature, sous-vide, deep frying and aseptic processing, which can be employed to achieve desirable texture, are also discussed in this chapter.