2.2. Butter samples
2.2.1. General
Two types of butter were produced, namely, (1) butter
fermented by L. helveticus MTCC 5463 (LH butter) and (2)
non-fermented butter (control).
2.2.2. Cream fermentation
Commercially purchased UHT-whipping cream (ARLA Foods,
Slagelse Dairy, Denmark) was used for fermentation prior to butter
production. Fermentation of cream was performed using 10% (v/v)
of activated lactobacilli obtained from Section 2.1 at 37 C for 24 h.
Upon fermentation, the fermented cream was refrigerated for 24 h
prior to churning.
2.2.3. Butter production
Control and LH butters were produced using a small scale laboratory setup according to the method of Britten, Lamothe, and
Robitaille (2008) with slight modification. Firstly, cream was
churned with a mixer Professional 600TM Series model (KitchenAid, US) at high speed (speed of 10) until separation of the fat
grains from buttermilk was observed. The churning process took
10 min and was maintained at 10–15 C throughout. Butter grains
were then pressed to remove the excess buttermilk. Next, the butter grains were mixed continuously with sterile cold water, four
times, to remove excess buttermilk. Lastly, the butter was shaped
into the desired shape, stored in plastic containers and kept refrigerated at 4 C. A similar churning process was performed separately for the production of LH butter using fermented cream.
2.3. Viable counts of L. helveticus
The viable counts of L. helveticus in cream, before and after fermentation, and fermented-butter were determined using the pour
plate method with MRS agar. Samples were serially diluted with
0.9% (w/v) sterilised NaCl and subsequently plated in duplicate,
followed by incubation at 37 C for 48–72 h.