Cell disruption and extraction techniques of bioactives from microalgae with a deep insight on enzymatic extraction and high-pressure homogenization

Abstract

Microalgae belong to the group of the oldest microorganisms that can grow in both fresh and marine water. Microalgal biomass is a rich source of vitamins, lipids, pigments and essential amino acids. Microalgal biomass can be used without cracking and fractionation or it can be cracked, fractionated and purified to get particular components like vitamins, pigments, omega-3 oils and proteins. But during cell disruption, it is difficult and still a challenge to maintain the functionality of extracted bioactive compounds. Therefore, there is a need to develop and optimize new efficient extraction technologies to get high value ingredients from microalgal biomass.

In this thesis the efficiency and optimization of two extraction technologies (high pressure homogenization and enzymatic extraction) was evaluated to get high value ingredients from Chlorella vulgaris. In this study lipid content % (% of sample weight), fatty acid amount in mg/g of sample and protein content % (% of sample weight) was determined at two levels of enzyme concentration (0.3 and 0.5%), temperature (30 and 45°C), incubation time (2 and 6 hr) and homogenization (homogenized or non-homogenized). Enzymes that were used are Viscozyme L and Neutrase and pH 5.5 was used for both enzymes and for all the samples. High pressure homogenization caused a statistically significant increase in lipid content and fatty acid amount as the homogenized samples were having more lipid content and fatty acid amount as compared to the non-homogenized samples and enzymes in the used concentration and conditions did not showed any effect for the lipid content and fatty acids in this study. For protein content % in samples, high pressure homogenization caused significant effect as non-homogenized samples showed more protein content and regarding enzymes higher concentration of used enzymes in combination with low temperature results in higher concentration of protein.

Popular Abstract

Microalgae cell disruption methods for extraction of bioactive compounds

Microalgal biomass is a rich source of lipids, essential amino acids, pigments and vitamins. There is an increasing global interest in exploiting microalgae for the production of food and feed ingredients. Microalgal biomass can either be used without fractionation or it can be cracked, fractionated and purified into specific healthy ingredients such as omega-3 oils, proteins, pigments, polyphenols and vitamins. To maintain the functionality of extracted bioactive compounds during cell disruption while obtaining high yields is still a challenge.

The overall purpose of this project was to provide an overview of available cell disruption methods and to evaluate the efficiency of two extraction technologies on the selected specie Chlorella vulgaris. Extraction technologies that were examined were; enzymatic extraction (biological method) and high-pressure homogenization (mechanical method). After the extraction total protein was determined by direct combustion, lipid content by gravimetry and fatty acid composition by GC-FAME.

To evaluate the efficiency of these two methods various combinations of homogenized and non-homogenized microalgae samples with two enzymes (Viscozyme L and Neutrase) were made. Experimental design was having four factors (each with two levels) which are homogenization (homogenized or non-homogenized), enzyme combination and concentration (Viscozyme, Neutrase 0.3 or 0.5%) incubation time (2 or 6 hr) and temperature (30 or 45 °C). % protein content, % lipid content and fatty acid amount in mg/g of samples were statistically evaluated against four factors after extraction.

Statistical analysis of % lipid content showed that among all the four factors only homogenization prior incubation causes significant difference in lipid content. Homogenized samples had higher lipid content as compared to non-homogenized samples and the presence of enzymes did not give any effect on lipid content. Same pattern was observed for fatty acid amount in mg/g of sample that only homogenized samples had higher fatty acid amount. Only one fatty acid (16:3, n-4) amount was affected by temperature as probably higher temperature (45°C) cause its oxidation and for for palmitoleic acid none of the factor was having significant effect on amount of palmitoleic acid. Statistical analysis of % protein showed that homogenization is the factor that cause significant difference in protein %. Non-homogenized samples had higher protein % because in homogenized samples during homogenization some of the protein may be degraded or released. Enzyme concentration showed interaction with temperature that was causing significant difference in % protein and higher concentration of enzymes in combination with low temperatute resulted in higher protein concentration in this study.

So, it can be concluded that in this study high pressure homogenization caused a significant difference in protein, lipid and fatty acid amount and the used concentration and combination of enzymes did not show any effect except for protein % and more research is required to study the effect of the enzymes including higher enzyme concentrations and screening various types of enzymes.

Master’s Degree Project in Molecular Biology 30 credits
Department of Biology, Lund University

Advisor: Charlotte Jacobsen (National Food Institute, Technical University of Denmark) (Research group for bioactives - Analysis and Application)

• author: Jahangir, Rizwan
• supervisor: Charlotte Jacobsen
• organization: Degree Projects in Molecular Biology
• course: MOBY10 20201
• year: 2020
• type: H1 - Master's Degree (One Year)
• subject: Biology and Life Sciences
• language: English
• id: 9031477
• date added to LUP: 2020-10-29 10:51:16
• date last changed: 2020-10-29 10:51:16