Production of probiotic low-calorie sour cream [electronic resource].

Includes references.

The production of probiotic low calorie sour cream was aimed to experiment in relation to its compositional, bacteriological. biochemical, rheological and organoleptic properties along the cold storage period of the product. Cream based on 36% total solids (TS) and 30 % fat was made using the obtained fresh cream (54 % TS and 50 % fat) and liquid skimmed milk (9 % TS).To produce low-calorie sour cream, fat content was lowered to 20 and 10 % depending on the addition of Simplesse IOOe to mimic milk fat on the basic of 0.1% fat mimetic is instead of 1.0% fat. Dried whey protein concentrate (DWPC, 95 % TS) was used as bulking agent to overcome the loss occurred in the TS content due to the reduction in the fat content. Thereafter, all creams were homogenized at 55-60°C and further heat treated to 74°C for 30 sec. followed by rapidly cooling to the appropriate temperatures. Then creams were inoculated with 2% freshly prepared bacterial starter culture and incubated at 30 or 37°C, to reach pH value about 4.6, for cream cultured with R-704 or ABT-2 type starter culture, respectively. The results indicated that. the proportional fat replacement ofcream led to gradual increase in the protein, carbohydrate and ash contents. and decreased the caloric value. There are a backward relationship between the bacterial population and the fat content of the sour cream. Where, in the product cultured with ABT-2 type, Laclobacillus acidophilus grew and predominated in all other accompanying strains overlooking either the fat content or the cold storage period (CSP). Sireplococcus Ihermophilus populated the 2nd predominance order followed by Bifidobaclerium sp., which tended to proximate and preceded. actually, Sir. Ihermophilus by prolonging the CSP of the lowest fat-content cream (10%). The increase rate of the bacterial count continued until 3'd weak for l.b. acidophillls and to ]01 weak for Bifidobaclerium sp.. Thereafter, gradual decreases were occurred. However, Sir. Ihermophilus began to decrease from the 101 day ofCSP. Although the count of bacterial type R·704 was always higher. it behaved a trend similar to that of Bifidobaclerillm sp. toward the CSP. Sour cream of ABT-2 type contained higher titratable acidity (TA) % as well as lower pH, acetaldehyde (AC) and diacetyl (DA) values than that cultured with R-704 type. Along CSP of sour cream the increment in AC, DA and TAcontents continued. in order. until the 7th ,14th and the end of the experimental period. As the protein content raised at the expanse of the fat content via adding DWPC, which was in the d':ilatured form, the firmness, consistency coefficient, and yield stress of sour crealil increased, especially when ABT-2 type was used and the CSP progressed. Furthermore, ABT-2 sour cream was sensory distinguished with, nearly, similar appearance as will as better flavour and consistency rather than that of R-704. The fat reduction to 20 % did not influence the overall sensory quality, while that of 10% fat attained panel score averaged 93.5 % of the control when ABT-2 type was used. As a conclusion, it is successfully possible to produce probiotic low calorie sour ,ream with excellent sensory attributes using Simplesse 100~ as fat mimetic and bacterial type ABT-2 as starter culture.

Summary in Arabic.

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