Preparation Of Germinated Quinoa Fermented Milk And Its Nutritional And Functional Evaluation

In recent years,the world faces new challenges and life expectancy has unavoidably increased due to exponential increase in global health challenges and high cost of health care.Functional foods has recently become a convenient and economical solution for chronic health problems,Dietary interventions by functional foods have recently been demonstrated to beneficially affect one or more target functions beyond adequate nutritional effects.Consequently,researches that support their optimization are currently on the rise to combat several diseases that pose as global health challenges.Quinoa(Chenopodium quinoa willd)is a food crop native to the Andean region,and has attracted a global growing interest.However,a major limitation to its use in food processing is the characteristic astringent bitter flavor.Processing techniques such as germination and fermentation had reportedly been proven to positively improve the nutritional,functional and structural quality of foods and food products.Therefore,the overall objective of this thesis was to evaluate the hypothesis that germination process optimizes the nutritional,functional and structural properties of quinoa yoghurt in order to enhance its usefulness in human health and nutrition.In this study,the variations in the nutritional and physicochemical changes of quinoa yoghurt(QY)before and after germination and fermentation processes(using conventional yoghurt starter culture and selected antidiabetic strains of Lactobacillus casei)were evaluated.The effect of germination on the QY structural,organoleptic and nutritional qualities as well as antioxidant capacity was assessed.Additionally,hypoglycemic and antihypertensive peptides of sprouted quinoa yoghurt beverage(QYB)were investigated.The hypoglycemic effects and mechanisms of sprouted QYB polyphenols,polysaccharides and oleanolic acid were evaluated.Furthermore,the glucose and cholesterol-lowering effect of sprouted QY in C57BL/6N mice were studied to further investigate their hypoglycemic and hypolipidemic potentials in T2 DM.In addition,the expressions of downregulate and upregulate gene markers in T2 DM were assessed using Real-Time Quantitative Reverse Transcription PCR(q RT-PCR)techniques.The results of this thesis showed that quinoa fermented products were organoleptically acceptable,and had physicochemical and exceptionally high nutritional qualities that were significantly(p<0.05)improved by germination process.The total phenolic content(TPC)and total flavonoid content(TFC)in germinated QY of both cultivars were higher in comparison with the non-germinated quinoa yoghurt(QY).Compared with the non-germinated QY,germinated QY significantly increased(p<0.05)the antioxidant capacities with 2,21,diphenyl-1 picrylhydrazyl scavenging activity(DPPH),ferric reducing antioxidant capacity(FRAP),radical cation(ABTS*+)scavenging assay and oxygen radical absorption capacity(ORAC)assays.In addition,it was observed that more phenolic compounds were detected in germinated QY of both cultivars when compared with the non-germinated QY.Among the functional components identified in QYB,oleanolic acid,polyphenols and polysaccharides significantly(p<0.05)demonstrated antioxidative,antidiabetic and antihypertensive characteristics that were optimized by germination process.The results showed that in a time-dependent manner,germination decreased the non-functional saponin contents per gram of the QYB from 0.41%(0 h)to 0.19%(72 h).Additionally,in vitro studies showed that sprouted QY reduced the activity of α-amylase in a time and concentration-dependent manner,comparable to the control drug acarbose.The assessment of the bioactive oleanolic acids(OA)in QYB showed that germination enhanced their antioxidant and antidiabetic capacities,especially after 24 h.Furthermore,OA isolates of QYB demonstrated anti-angiogenic activities on human umbilical endothelial cells(HUVECS);and the highest ability to inhibit angiogenesis was observed with OA isolated from 24 h germinated QY.In NCI-H716 cells,polyphenol and polysaccharide(PPE)isolates and conjugates of sprouted QYB significantly stimulated the secretion of glucagon-like peptide-1(GLP-1),influenced proglucagon and prohormone convertase 3 m RNA expressions,HNF-3γ and CCK-2R gene protein expression,as well as stimulated the release of cytosolic calcium in the cells.In a dose-dependent manner,PPE isolates and conjugates of sprouted QYB significantly(p<0.05)increased the stimulation of GLP-1.Bioactive peptides of QYB optimized by germination-influenced hydrolysis demonstrated a dual inhibitory action on α-glucosidase enzyme and angiotensin-converting enzyme(ACE).All protein hydrolysates exhibited a dose and strain-dependent inhibition on the enzymes.The inhibitory peptide fractions by RP-HPLC showed activities as high as 127 ± 4.29 mg/m L and 10.39 ± 4.73 mg/m L against ACE and α-glucosidase respectively.Among the peptide sequences identified,both LAHMIVAGA and VAHPVF significantly had inhibitory activities on α-glucosidase and ACE.The hypoglycemic assessment of QY in this study showed that it remarkedly enhanced glucose uptake and hepatic liver glycogen in HFD/STZ-induced T2 DM mice.Additionally,the result showed that QY significantly(p<0.05)reduced oxidative stress and demonstrated cholesterol-lowering effects in T2 DM mice.Germination significantly(p<0.05)influenced the glucose and lipid homeostasis in the T2 DM mice in such a way that sprouted QY recorded highest hypoglycemic and cholesterol-lowering effects when compared with the non-germinated QY.The q RT-PCR analysis showed that QY exerted its anti-hyperglycemic and antihyperlipidemic effects through the AKT/AMPK/PI3 K signaling pathway.Furthermore,the histopathological and immunohistochemical studies showed that the inclusion of QY in the diet of T2 DM mice restored the shape and structural integrity of damaged liver cells;thus,confirmed its potential to increase pancreatic β-cells population and function.In conclusion,the results obtained demonstrated that germination influenced the functional and nutritional properties of quinoa fermented products to a large extent due to the fact that inherent macromolecules and phytochemicals such as functional saponins,polyphenols and polysaccharides that are beneficial to human health became more bioavailable.Germination also inactivated or reduced to safe levels the anti-nutritional factors in the quinoa grain prior to yoghurt production;while functional saponins were optimized.In addition,the potential antidiabetic activity of the sprouted polyphenols and polysaccharides conjugates as GLP-1 secretagogues was enhanced by germination process which invariably influenced the hydrophobic interactions and hydrogen-bonding between them.It was also concluded that protein hydrolysates and peptides of sprouted QYB potentially regulated post-prandial hyperglycemia and hypertension in vitro.Finally,the studies in vivo successfully demonstrated that sprouted QY ameliorated hyperglycemia via the regulation of glucose and lipid homeostasis.Overall,this thesis established that beyond the improvement of essential nutrients and quality,an inexpensive germination process successfully optimized the functional attributes of the quinoa fermented products investigated in this study such as antioxidant,hypoglycemic,antihypertensive,antiangiogenic activities.Therefore,the germinated and fermented quinoa products could be considered as functional foods with potentials as dietary intervention in human health and nutrition.