PENGARUH PENAMBAHAN EKSTRAK UMBI BENGKUANG (Pachyrhizus erosus) DAN UBI JALAR UNGU (lpomoea batatas [L.] Lam) TERHADAP KUALITAS YOGHURT PROBIOTIK DENGAN Lactobacillus rhamnosus SELAMA PENYIMPANAN
SHINTA OCTARINA WIBIYANTI, Endang Wahyuni, S. Pt., M. Biotech
2014 | Skripsi | S1 ILMU DAN INDUSTRI PETERNAKANPenelitian ini bertujuan mengetahui pengaruh penambahan ekstrak umbi bengkuang (Pachyrhizus erosus) dan ubi jalar ungu (Ipomoea batatas [L.] Lam) terhadap kualitas kimia, sensoris, dan mikrobiologis yoghurt selama penyimpanan. Yoghurt dibuat dari susu segar, susu skim 5% (b/v) dengan penambahan 10%(v/v) (ekstrak umbi bengkuang, ubi jalar ungu, dan campuran keduanya) serta tanpa ekstrak sebagai kontrol kemudian diinokulasi Streptococcus thermophilus, Lactobacillus bulgaricus, dan probiotik Lactobacillus rhamnosus (1:1:1) sebanyak 3% (v/v). Parameter yang diuji yaitu pH, kadar keasaman, air, aktivitas antioksidan, sensoris, total BAL dan probiotik. Hasil penelitian menunjukkan bahwa nilai pH yoghurt kontrol (4,11±0,12) lebih tinggi dibandingkan yoghurt penambahan 10% ekstrak umbi bengkuang (3,92±0,09), ubi jalar ungu (3,86±0,07), dan campuran (3,93±0,10). Keasaman tertinggi pada yoghurt penambahan 10% ekstrak ubi jalar ungu (1,52±0,11%), dibandingkan campuran (1,33±0,19%), umbi bengkuang (1,25±0,09%), dan kontrol (1,15±0,15%). Lama penyimpanan menyebabkan kenaikan kadar keasaman dan penurunan pH. Tidak terdapat perbedaan kadar air pada yoghurt kontrol maupun yoghurt penambahan ekstrak. Aktivitas antioksidan tertinggi yaitu yoghurt penambahan 10% ekstrak ubi jalar ungu (55,82±4,19%). Penambahan ekstrak tidak meningkatkan sensoris yoghurt. Total BAL dan viabilitas probiotik yoghurt penambahan 10% ekstrak campuran minggu kedua (9,22±1,16 dan 8,04±0,66 log cfu/ml) lebih tinggi daripada yoghurt penambahan 10% ekstrak umbi bengkuang (8,84±0,19 dan 7,54±0,50 log cfu/ml), ubi jalar ungu (8,35±0,90 dan 7,14±0,26 log cfu/ml), maupun kontrol (8,18±0,41 dan 6,88±0,53 log cfu/ml). Penelitian disimpulkan bahwa ekstrak campuran umbi bengkuang dan ubi jalar ungu pada yoghurt probiotik mampu meningkatkan kualitas kimia (memiliki aktivitas antioksidan 37,88±1,05%), namun tidak meningkatkan kualitas sensoris. Viabilitas Lactobacillus rhamnosus dipertahankan hingga 8,04±0,66 log cfu/ml dalam dua minggu penyimpanan.
This research was done to study the effect of yam tuber (Pachyrhizus erosus) and purple sweet potato (lpomoea batatas [L.] Lam) extract addition on the chemical, sensoric, and microbiological quality of yogurt during storage. Yogurt was made from fresh milk, 5%(w/v) of skim milk with 10% addition of extract of yam tuber, purple sweet potato, and mixture of both extract (1:1), yogurt without extract was used as control, and then was inoculated with Streptococcus thermophilus, Lactobacillus bulgaricus and probiotic of Lactobacillus rhamonus. Experiment data were pH value, content of acidity and water, antioxidant activity, sensoric, lactic acid bacteria and probiotic viability of yogurt. Control yogurt had higher of pH value (4,11±0,12) than the others. Yogurt with 10% extract of purple sweet potato had more acidity (1,52±0,11%) than yoghurt with 10% extract of mixture (1,33±0,19%), yam tuber (1,25±0,09%) and also control (1,15±0,15%). Prolonged refrigerated increased acidity properties and decrease pH value. There was no significant difference on water content in control and yogurt with 10% exctract of yam tuber or purple sweet potato. The highest antioxidant activity recorded in yoghurt with 10% extract of purple sweet potato (55,82±4,19%). Addition of extract did not increase the sensoric yogurt. Total lactic acid bacteria and probiotic viability show that yogurt with 10% extract of yam tuber and purple sweet popato mixture (9,22±1,16 and 8,04±0,66 log cfu/ml) on week 2nd had significantly higher than yogurt with 10% extract of yam tuber (8,84±0,19 and 7,54±0,50 log cfu/ml), yogurt with 10% extract of purple sweet popato (8,35±0,90 and 7,14±0,26 log cfu/ml) and control (8,18±0,41 and 6,88±0,53 log cfu/ml). Conclusion of this experiment was 10% mixture of extract of both purple sweet potato and yam tuber increase chemical quality (antioxidant activity of the yogurt was 37,88±1,05%). Viability of Lactobacillus rhamnosus was 8,04±0,66 log cfu/ml on probiotic yogurt after 2 week refrigerated storage.
Kata Kunci : Probiotic yogurt, Yam tuber, Purple sweet potato, Lactobacillus rhamnosus, Antioxidant activity
