Production And Stabilization Of Cloudy Olive Juice Beverage

Olives are rich in polyphenols which are responsible for many health benefits but thetraditional processing methods of Chinese olives for example stir-fry dishes involveloss of polyphenols due to high temperatures. The cultivated Chinese olive has aspecial flavor, contains nutritional and functional components and unlike itsMediterranean counterpart contains relatively low oil content which attributesqualifies them to be exploited for juice production, unfortunately exploitation of theChinese olives for juice production is still in its infant stage. The present research wasset with the aim of developing a cloudy olive beverage using Chinese olives.The specific chemical composition (amino acid profile, total polyphenol content andfatty acid composition) of the big and small Chinese olives pulp was determined. Theresults showed that the total amino acids content was 8.24 % and 9.48% for small andbig olives respectively and both olive varieties contained 7 of the 8 amino acids.Determination of the total phenolic content indicated 256 mg/100g and 376 mg/100gfor small and big Chinese olive pulp respectively. Identification of phenoliccompounds present in the pulp was also performed using HPLC analysis resulting inidentification of gallic acid, pyrocatechol, protocatechic acid, chlorogenic acid,syringic acid, vanillin, ferulic acid and quercetin as being present in the olive pulp.The main fatty acids in the pulp of the olives(big) were found to be oleic acid(55.16% of oil content) and contained about 70% unsaturated fatty acids.Using an L9 (34) orthogonal array for experimental design and analysis, the optimumconditions increasing the juice yield such as hydrolysis temperature, hydrolysis timeand enzyme concentration for pectinase enzymatic maceration were determined whichconditions were found to be temperature 25°C, hydrolysis time 1 hr and 0.05%enzyme concentration which led to a minimum juice yield of 64% in comparison tothe 43% obtained without enzyme. Enzyme concentration was found to be the mainfactor followed by temperature and lastly time.Since cloud stability is a major problem encountered in cloudy beverages, theinfluence of five kinds of stabilizer (CMC, PGA, sodium alginate, xanthan gum andcarragenean) on the stability of cloudy olive juice beverage was studied. By visualobservation of sedimentation after 7 days, comparison the cloud stability of thebeverage samples after centrifugation at 3050 rpm for 15 min with different stabilizersand/or concentrations in addition to viscosity, xanthan gum (0.1%) was found to bethe best stabilizer followed by CMC (for acidic conditions) at 0.05%.Furthermore, homogenization pressure influence on the cloud stability and particledistribution of cloudy Chinese olive juice beverage was studied. Cloud stability andparticle distribution of the juice beverage homogenized at different pressures (20, 30,40 and 50 MPa) were determined and the results showed that the juice systemhomogenized at a pressure of 30 MPa obtained relatively small particle size (1.141μm)and distribution range and also had a high opalescence (OD660nm=0.915) aftercentrifugation at 3050 rpm for 15 min, which indicative of high cloud stability.Intense non enzymatic browning of the juice beverage occurred duringhomogenization and thus an investigation to control this undesirable effect wasconducted by addition of ascorbic acid at various concentrations and determining thehunter L-values after homogenization, which results showed that ascorbic acid atconcentration of 0.05% was effective at curbing the browning.To improve the olive juice beverage taste, the olive juice beverages were formulatedthrough addition of sugar at different concentrations, salt and aspartame after whichthe samples were sensory evaluated using a 15 member panel to determine the mostpreferred sample and finally a juice beverage with special olive flavor was obtained.The storage conditions including pH and storage temperature necessary for attainmentof a stable beverage with a long shelf life were investigated in addition to thedeterioration of the juice components and attributes such as total sugars, vitamin C,cloudiness and color. A pH level of 3.5 and 4 °C up to ambient temperature were thestorage conditions that led to better juice beverage characteristics and longer shelf liferesulting in a shelf life of more than 5 months.