Judul: Karakteristik Whey Kefir dan Aktivitasnya terhadap Penghambatan Angiotensin Converting Enzyme (ACE)
Abstrak: Whey is by product of cheese process that could be reached 80% of milk as cheese raw material. Whey contain the high of organic matter that could be potential to be exploited. Microbial fermentation by kefir grain can be used to utilize the whey. Bacteria and yeasts are growth simultaneously in kefir grain. Milk based fermentation product may contain bioactive peptides as functional foods, such as antihypertensive. This bioactive peptide could inhibit the angiotensin converting enzyme (ACE) activity, an enzyme that plays a role in the Renin Angiotensin Aldosterone system as a function of blood pressure regulation in human body. This research was conducted to evaluate the characteristic of whey based kefir product and its activity to inhibit the ACE. Kefir was produced by many type of whey as a treatment, SK : skim milk based kefir (control); WK : gouda cheese whey based kefir; and WKB : commercial whey powder based kefir, in three replication. Kefirs were evaluated for physical and chemical properties (pH, total titratable acidity, viscosity, protein, fat, lactose, and alcohol), microbiological (Lactic acid bacteria and yeast population), peptide concentration, ACE inhibition, IC50 and Inhibition Efficiency Ratio (IER). Data were analyzed by ANOVA, and continued by multiple comparison tests using Tukey’s HSD method. The results showed that the types of whey used for kefir productions significantly affected the physical and chemical characteristic of the products (P<0.05). Characteristics of whey kefir products were complaid to the CODEX STAN 234-2003 standards. Total lactic acid bacteria and yeast population of the products were not significantly different among whey types (P>0.05). The peptide concentration and ACE inhibitor activity of WK was 1.54 ± 0.02 mg/ml and 73.07 ± 0.91 % respectively. The values were significantly higher (P<0.05) than that of the control and WKB. IC50 of WK was 0.83 ± 0.02 mg/ml, significantly lower than that of control (1.05 ± 0.01 mg/ml) and WKB (0.96 ± 0.01 mg/ml). IER of WK was (47.35 ± 0.09 % per mg/ml), not significantly different (P>0.05) compared with control (47.19 ± 0.09 % per mg/ml) but significantly higher (P<0.05) than that of WKB (45.75 ± 0.18 % per mg/ml). General organoleptic test shows that the type of whey significantly affected (P<0.05) the panelist preferences on the sensory characteristic of whey kefir products. General sensory test result of WK was lower than that of SK but higher than that of WKB. Based on the plot of the intensity of sensory attributes, WK was in general between SK and WKB. The sensory properties that dominate the whey kefir product were specific kefir flavor, sour, compact and viscous texture. It was concluded that whey could be utilized for whey kefir production. Whey kefir has capability to be peptide bioactive sources for antihypertention agent. Whey kefir made from the Gouda cheese whey showed the higher ACE inhibitor activity than that of kefir based from commercial whey. Process optimization is necessary to meet the consumer preferences. The type of ACE inhibitor bioactive peptide in whey kefir product is also need to be further investigated.
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