Probiotic Frozen Yoghurt Production Using Camel Milk (Camelus dromedarius) with Improved Functions by Strawberry Guava (Psidium littorale var. cattleianum) Fortification

Abstract

In this study, Probiotic Yoghurt (PY) was produced by adding skimmed milk powder (5% w/v) and probiotic culture (7% w/v) (Lactobacillus bulgaricus, Lactobacillus acidophilus, Streptococcus thermophilus and Bifidobacterium ssp.) to heat-treated camels (Camelus dromedarius) milk. Sahlep (Orchis sanctum L.)  (2% w/v) and skimmed milk powder (15% w/v) were added to the camel milk which was then divided into two batches. The 1st batch was fortified with 20% strawberry guava (Psidium littorale var. cattleianum). The 2nd batch was prepared without guava fruit fortification. The mixture was then homogenized with probiotic yoghurt at a 40:60 ratio to yield probiotic guava frozen yoghurt (GPFY) and plain Probiotic Frozen Yoghurt (PFY) samples. Samples were stored for 120 days at -20±1°C. Physicochemical, microbiological and sensory analyses were conducted on the 1st, 15th, 30th, 60th and 120th days of storage. A significant relationship was found between the sahlep and fruit fortification with the physicochemical properties of the ice creams (P< .05). Vitamin C losses were low in GPFY samples. During storage, Lactobacillus bulgaricus, Lactobacillus acidophilus and Bifidobacterium ssp. counts in PFY samples first decreased and then increased. The decrease in GPFY was lower and the increase higher than in PFY. Streptococcus thermophilus decreased in PFY during storage whereas in GPFY it decreased until the 30th day and increased in the further days of the storage. In all PFY samples, the relationships between fat content, sahlep ratio and fruit fortification with the viability of the microorganisms were significant (P< .05).