Uht treatment of liquid egg yolk

Absztrakt

Egg and its product are easily perishable items because of their high moisture content, although they have a very high amount of nutrients, especially protein. Many efforts have been channelled to increase the shelf-life of these products but heat treatment according to literature is the most promising although egg and its products are heat-sensitive. Thus, a very low temperature is needed or a high temperature for a very short time. Ultra-Heat Treatment (UHT) is one of the known technologies that we used for heat-sensitive products.

The aim of the study was to investigate the effect of UHT treatment (approximately 67 °C for 190 seconds) on Liquid Egg Yolk (LEY) and Liquid Egg Yolk with additive (LEYA). During twenty-one days, the pH and colour were measured every seven days for all the samples. Emulsion stability was also studied by the methods of heat stability for mayonnaise. pH and colour measurements were used assess the quality of liquid egg yolks after 21 days of storage. From the results, raw LEY had the shortest shelf life and gave off a foul smell after 14 days of storage with significant colour changes. Addition of citric acid as an additive however improved the shelf life of the LEY with a relatively low pH. UHT treated LEY also showed improved shelf life of the LEY with a relatively constant pH from day 14 until the end of the experiment (day 21). UHT treatment of LEY with addition of addition of citric acid as an additive may help optimise the shelf life of the product.