Low fat UF-feta cheese production containing xanthan gum

Consumption of high fat diet is associated with various chronic diseases. This association has created increased consumer awareness and an increase in the demand for low-fat foods, including cheese (Nishinari et al., 2000). However, the consumption of low/reduced-fat cheese is still low demand between consumers. Low-fat cheese faces great challenges associated with its texture being hard and rubbery and lack of flavor (Olivera et al., 2011). In an effort of improving the quality of low-fat, different hydrocolloids could be used. Ultrafiltered processed feta cheese is the major industrial produced cheese in Iran and is very popular between consumers. Because of having high fat content, in this research feasibility of lowering fat in ultrafilterd feta cheese through substitution with xhantan gum have been surveyed. To prepare low fat feta cheese, raw milk was passed from ultrafiltration system to reach 34% solid non- fat then fat content of retentate was decreased from 16% to 8% by skim milk addition. The xhantan gum at the levels 0 (control), 0.1, 0.3 and 0.5% based on retentate content was added. After inoculation with lactic acid bacteria and chymosin, coagulation was performed at 30oC for 20 min. The 3% salt was poured to all of the samples equally and maturation conducted at 27oC until pH 4.6. The prepared samples were evaluated for chemical properties (pH, acidity, salt, fat and solid non-fat, lipolysis and proteolysis), texture properties (softness, chewiness, gumminess, and springiness) and overall acceptability during storage period 0, 15, 30 and 45 days of storage. Preparation of treatments were carried out in triplicate and the data obtained from the above mentioned evaluation parameters were analyzed based on Factorial design and Duncan's multiple range comparison test. The results showed that the amount of gum addition had no significant effect on fat content, whereas pH and solid non-fat content decreased significantly by adding gum (p<0.05). Control and samples containing 0.5% xhantan gum had the least and the most moisture content, respectively. The intensity of water holding capacity as a result of fat to protein balance lowering along with fat reduction has been mentioned by Volikalis et al., 2004. Ratio of lipolysis as milk fat degradation and proteolysis as decomposition of proteins indicator were increased in parallel with xhantan gum addition. Lipolysis is a water content dependent reaction so this phenomenon was occurred in a lower rate in full fat cheese (control) as a result of lower moisture content of them (Kwak et al., 2004). Presence of hydrocolloids probably due to water entrapment in cheese matrix could be lead to free fatty acid release. These indices also increased during the storage period until the 45th day (p<0.001). Gradually increment of soluble nitrogen during storage period is a common phenomenon and described as maturation and flavor development in cheese but its increase along with xhantan gum addition could be interpret by Zhisu and Shah (2005) expression which they have mentioned a parallel relationship between moisture content and proteolytic enzyme activities. The texture profile analysis resulted that cheese samples prepared with 0.5% xanthan gum, had low softness, whereas springiness, gumminess and chewiness of them increased. Also, based on panelist judgement, xhantan gum addition lead to lightness and whiteness lowering and was an undesirable but from the overall acceptability viewpoint, UF white cheese prepared from 0.5% gum got the best score. It was concluded that to achieve a low fat Uf-feta cheese, use of xhantan gum could be an appropriate choice. It did not cause any adverse effect on taste and other sensorial parameters which is the main reason of cheese selection by consumers. The addition of xhantan gum improved the texture of low-fat UF-cheese by reducing the hardness, gumminess, and chewiness which has been challenging and a universal complaint about low-fat cheeses.