Sample Solution

Abstract: Rheological, chemical and sensory properties of processed cheese fortified with different levels of tomato (1%, 2% and 4% wt/wt) and asparagus (0.5%, 1% and 1.5% wt/wt) powders were analyzed. Both of the powders decreased the pH and lipolysis indexes and increased proteolysis extent of processed cheese. Phenolic and lycopene content and antioxidant activity decreased during storage of 3 month. The frequency sweep test and temperature sweep test showed that all samples had Gʹ > Gʺ, indicating that, solid-type structures were present. Tomato powder decreased the solid like behavior of processed cheeses. However, asparagus powder led to a more elastic structure in the processed cheese. Control sample and processed cheese with low level of tomato powder had highest scores of flavor, color and total acceptance and also processed cheese samples containing asparagus powder were significantly (P < 0.05) more rigid and less spreadable compared with control samples which corresponded to results obtained by dynamic oscillation rheometry. Results showed that low levels of tomato and asparagus powders could be used for fortification of processed cheese.

Keywords: processed cheese, tomato, asparagus, frequency sweep, Temperature sweep

INTRODUCTION

Processed cheeses are stable oil-in-water emulsions made by heating a mixture of cheeses, edible oils/fats and other dairy and nondairy ingredients in the presence of emulsifying salts1. They are being used increasingly because of their cost-effectiveness, attributed to the simplicity in their manufacture and the replacement of selected milk ingredients by cheaper vegetable products. However, processed cheeses are low in functional and bioactive ingredients which should be enhanced by the addition of some valuable ingredients2.
Asparagus contains flavonoids (mainly rutin) and other phenolic compounds, which possess strong antioxidant properties. With abundant cellulose and phytochemicals present, asparagus may be a promising source of new value-added compounds, including phenols, flavonoids, hydroxycinnamic acids, as well as a dietary fiber3.
Tomato is also a good source of carotenes and phenolic compounds and provides a significant proportion of total antioxidants in the diet. Lycopene is the most important carotenoid in tomato and is responsible for the color of tomato fruits and their derived products. The seeds and skin of tomato are rich sources of minerals4.
There are several researches about fortification of different kind of cheeses with functional ingredients such as fish oil emulsion5, spice and herb extracts6 (cinnamon stick, oregano, clove, pom