Formulation of Synbiotic Yogurt with Modified Purple Yam Starch Incorporation: Evaluation of Syneresis, Probiotic Bacterial Viability, and Organoleptic Acceptance / Formulasi Yoghurt Sinbiotik dengan Inkorporasi Pati Uwi Ungu Termodifikasi: Evaluasi Sineresis, Viabilitas Bakteri Probiotik, dan Daya Terima Organoleptik

Background: Yogurt quality improvement can be achieved through synbiotic formulations combining probiotic bacteria (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus rhamnosus) with prebiotics from modified purple yam starch (Dioscorea alata). This plant contains 7.54% inulin and has potential as a natural stabilizer, but its utilization in synbiotic yogurt remains suboptimal. This study aims to evaluate the effect of modified starch incorporation on probiotic viability, physical stability, and sensory acceptance. Objective: This research aimed to examine the capability of modified purple yam starch as a prebiotic source in synbiotic yogurt, focusing on its impact on syneresis, bacterial viability, and organoleptic properties. Methods: An experimental study using a Completely Randomized Design (CRD) with six treatments. The process included purple yam starch extraction, starch modification via autoclaving (110°C and 121°C), yogurt fermentation using three bacterial strains, and evaluation of pH, syneresis, Total Plate Count (TPC), and hedonic tests by 20 panelists. Data analysis involved descriptive statistics, Mann-Whitney, and Spearman correlation tests. Results: Yogurt formulations with modified yam starch yielded optimal pH (6.81 with L. rhamnosus) and highest syneresis (30.02%). Bacterial viability reached 431 × 10³ CFU/mL (10⁻² dilution) for L. rhamnosus. Organoleptic tests showed the highest scores for aroma (6.90 ± 0.31) and a significant correlation between taste-thickness (ρ=0.52; p<0.05). Color was consistent (score 6), while texture preference varied (scores 5-7). Conclusion: Modified purple yam starch effectively functions as a prebiotic and stabilizer in synbiotic yogurt, supporting probiotic viability and sensory acceptance. This formulation holds promise as a functional food product utilizing local ingredients.

Latar Belakang: Peningkatan kualitas yoghurt dapat dicapai melalui formulasi sinbiotik yang menggabungkan bakteri probiotik (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus rhamnosus) dengan prebiotik dari pati termodifikasi umbi uwi ungu (Dioscorea alata). Tanaman ini mengandung inulin 7,54% dan berpotensi sebagai stabilizer alami, namun pemanfaatannya dalam yoghurt sinbiotik belum optimal. Penelitian ini bertujuan mengevaluasi pengaruh inkorporasi pati termodifikasi terhadap viabilitas probiotik, stabilitas fisik, dan penerimaan sensori produk. Tujuan: Penelitian ini bertujuan untuk menguji kemampuan pati termodifikasi uwi ungu sebagai sumber prebiotik dalam yoghurt sinbiotik, dengan fokus pada pengaruhnya terhadap sineresis, viabilitas bakteri, dan karakteristik organoleptik. Metode: Penelitian eksperimental menggunakan Rancangan Acak Lengkap (RAL) dengan enam perlakuan. Proses meliputi ekstraksi pati uwi ungu, modifikasi pati dengan autoklaf (110°C dan 121°C), fermentasi yoghurt menggunakan tiga strain bakteri, serta evaluasi parameter pH, sineresis, Total Plate Count (TPC), dan uji hedonik oleh 20 panelis. Analisis data mencakup uji statistik deskriptif, Mann-Whitney, dan korelasi Spearman. Hasil Penelitian: Formulasi yoghurt dengan pati uwi ungu menghasilkan pH optimal 6,81 (L. rhamnosus) dan sineresis tertinggi 30,02%. Viabilitas bakteri mencapai 431 × 10³ CFU/mL (pengenceran 10⁻²) untuk L. rhamnosus. Uji organoleptik menunjukkan skor tertinggi untuk aroma (6,90 ± 0,31) dan korelasi signifikan antara rasa-kekentalan (ρ=0,52; p<0,05). Warna yoghurt konsisten (skor 6) dengan preferensi tekstur bervariasi (skor 5-7). Kesimpulan: Pati termodifikasi uwi ungu terbukti efektif sebagai prebiotik dan stabilizer dalam yoghurt sinbiotik, mendukung viabilitas probiotik dan diterima secara sensori. Formulasi ini berpotensi dikembangkan sebagai produk pangan fungsional berbasis bahan lokal.