Ripening process of butter

The thermal treatment of the cream, also known as ripening, is the most time-consuming step in butter production; however, it governs the crystallization of the fat and thereafter the consistency of the butter.

Ripening is needed for production of desirable flavor and aroma in butter; also facilitates exhaustive churning. Ripening improves the keeping quality of un-salted butter but reduces the keeping quality of salted butter.

Ripening involves addition of starter culture, mixing it thoroughly and storing the cream (incubating) at controlled temperature. Traditionally cream for ripened cream butter is fermented by selected lactic acid bacteria, which produce lactic acid from lactose and diacetyl (principal flavouring component in ripened cream butter) from citric acid.

Starter culture consisting of a mixture of both acid producing (Streptococcus lactis, S.cremories) and flavour producing (S.diacetylactis, Leuconostoc citrovorum and/or Leuc. dextranicum) organisms is added. Amount of starter added depends on several factors and usually ranges between 0.5-2.0 percent of the weight of the cream.

The cream is ripened to pH 5.5 at 21°C and then pH 4.6 at 13°C to arrest further acid development. Most flavor development occurs between pH 5.5 - 4.6. Biosynthesis of diacetyl is not sufficient above pH 5.5.

The colder the temperature during ripening the more the flavor development relative to acid production. Ripened butter is usually not washed or salted.
Ripening process of butter

Processing of Kefir

It is a fermented milk drink which has its origin in the Caucasus Mountains of Russia. Kefir can be made from any type of milk, cow, goat, sheep, coconut, rice or soy. There are many choices for milk; pasteurized, unpasteurized, whole fat, low fat, skim and no fat.

The first step is to homogenize the milk to 8% dry matter and held by heat treatment at 90-95 °C for 5-10 minutes. The cooled at 18-24 °C and inoculated with 2-8% kefir cultures in tanks.

Kefir is produced by the fermentation of lactic acid and alcohol by mesophilic bacteria and yeasts, respectively. The vital function of lactic acid starters is for fermentation of lactose into lactic acid. In addition, they also contribute to flavor, aroma and alcohol production, while inhibiting interference of spoilage microorganisms.

Kefir can also be prepared by inoculating milk with kefir grains which are a combination of bacteria and yeasts in a symbiotic matrix. Kefir grains consist of protein and polysaccharide matrix containing different species of yeasts, LAB, acetic acid bacteria, and mycelial fungi.

After heat treatment and cooling to 22 ºC and then later inoculated separately with 1.5 % (w/v) kefir grains previously activated.

Fermentation was performed at thermostatic bath at 22 ºC for 48 h. The kefir grains were then separated from the product with a sieve and then preserved in sterilized skimmed milk under refrigeration at 4 ºC for future fermentations. The product was cooled and stored at 4 ºC for the final 28 days.

Microorganisms involved in kefir production secrete exopolysaccharides that accumulate along with proteins and fat molecules to form kefir grains. Further, growth of kefir grains occurs by the accumulation of microbial biomass on the pre-existing kefir grains during kefir production.

Kefir produced through the fermentation of milk by the microorganisms is a white or yellowish colored, sour, carbonated and a mild alcoholic beverage.
Processing of Kefir