Cyprian Ogombe Odoli will defend his doctoral dissertation in food science on Thursday 22 October. The ceremony takes place in the Celebration Hall of the University of Iceland and starts at 14:00.
The thesis is entitled: Drying and smoking of capelin (mallotus villosus) and sardine (sardinella gibbosa) - the influence on physicochemical properties and consumer acceptance.
Opponents are dr. Morten Sivertsvik, professor and division manager at Nofima, Norway, and dr. Hjörleifur Einarsson, professor at the Faculty of Natural Resources at the University of Akureyri.
The supervisor of the project was Sigurjón Arason, chief engineer at Matís and professor at the Faculty of Food and Nutrition at the University of Iceland. In addition to him, Guðjón Þorkelsson, director of Matís and professor at the Faculty of Food and Nutrition at the University of Iceland, dr. Kolbrún Sveinsdóttir, project manager at Matís, dr. Tumi Tómasson, director of the United Nations University School of Fisheries, and Ásbjörn Jónsson, project manager at Matís.
Dr. Þórhallur Ingi Halldórsson, professor at the Faculty of Food and Nutrition, University of Iceland, will chair the ceremony.
Abstract
Drying and smoking are cost-effective preservation methods commonly used in developing countries, where underdeveloped transport processes restrict the marketing of fresh fish. In East Africa, dried and smoked fish is an important source of protein in the diet of the population. Small fish, mainly sardines, are usually placed in brine and pre-cooked to stop enzyme activity and microbial growth before being dried outdoors. The dried fish is often of poor quality and its sales are limited to lower-income groups shopping in outdoor markets. At the same time, there is an increasing demand among middle-class consumers for dried and smoked small fish in supermarkets that meets their quality requirements. This demand could be met through imports or improved processing methods. The aim of this study was to improve the quality and safety of small fish processing and to examine consumers' reactions to a new product such as dried capelin caught in Iceland, which is not known in the markets in East Africa. The effects of preheating, drying and smoking on product quality were assessed, as well as the effect of packaging methods on fat degradation. Sensory evaluation properties and the amount of microorganisms in dried and smoked products were also examined. Finally, the goal was to set a goal for healthy dried sardines and imported dried capelin.
Conventional drying and pre-drying for sardine and capelin drying resulted in lower product quality, poorer sensory evaluation and lower protein quality. The amount of fat in capelin is seasonal and when capelin with a fat content of 9-10% instead of 7-7.5% was dried, the drying took longer and the moisture content of the final product increased. At the same time, the fat reduced the deformation of proteins during the processing process. Under controlled drying conditions, the quality of the products increased, which indicates that it is necessary to develop a dryer for processing small fish. In dried and smoked capelin and sardines, a high proportion of essential polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were detected, exactly 13% in capelin and 20% in sardines. Hot-smoked capelin and sardines had a higher fat content, less moisture content and increased stability against microorganisms, compared to a cold-smoked product, but hot smoking reduced utilization. The fat content affected the hydrolysis of proteins, oxidation of fats and improved sensory evaluation properties during storage of smoked and dried capelin. Fat degradation was highest in low-fat capelin, while development was highest in high-fat capelin. Packing smoked and dried fatty capelin in anaerobic packaging resulted in less fat degradation and fewer microorganisms. Packaging did not affect fat breakdown.
Hot-smoked fish in anaerobic packaging retained its original properties after four weeks of storage. Dried capelin with a moisture content below 25% and a water activity below 0.7 is stored undamaged at room temperature for five months in anaerobic packaging. Improved processing processes for drying sardines and capelin yielded good results and the product was well received by consumers of traditional dried small fish in Kenya. The results of this study show that dried and smoked small fish can be a very nutritious food and if the processing and packaging procedures are correct, the consumption of these products could significantly reduce malnutrition prevalent in developing countries.
About the doctoral dissertation
Cyprian Ogombe Odoli was born in Kenya in 1974. In 2006, he graduated United Nations University School of Fisheries and subsequently the school has supported him for master's and doctoral studies. Cyprian graduated with an MS in food science from the University of Iceland in 2009 and enrolled in a doctoral program at the same department three years later, in 2012. He is married to Hellen Namugeere and they have two children.
Doctoral student: Cyprian Ogombe Odoli - coo1@hi.is – cogombe@yahoo.com (mobile: 8627565).
For more information, contact Cyprian Ogombe Odoli and Sigurjón Arason, Matís' chief engineer.