Effect of Passion Fruit Peel Powder on the Gelation Characteristics of Non-rinsed Tilapia Surimi

The effect of passion fruit peel powder (1%、2%、3%、4%、5%) on gel properties of non-rinsed tilapia surimi was investigated. The whiteness, TPA, gel strength, water holding capacity (WHC), cooking loss rate, and water migration were analyzed. The results showed that the hardness, gel strength and WHC of surimi gel significantly increased with increasing addition of passion fruit peel powder up to 4%, and then the hardness, gel strength and WHC declined, while the cooking loss rate decreased first and then increased, the whiteness gradually decreased. Further analyses in low-field NMR revealed that passion fruit peel powder could change the transverse relaxation time, enhanced the combination with water and altered the distribution of different water categories. The addition of passion fruit peel powder changed the water state in surimi gel. The proportion of bound water and non-easy flowing water increased, and the proportion of free water decreased. The change was most obvious when the addition amount was 4%. Based on the above results, addition of 4% passion fruit peel powder was most beneficial to improve the gel characteristics of non-rinsed tilapia surimi.