VARIASI RASIO SARI BIT MERAH (Beta vulgaris L.), SUSU SKIM, DAN KULTUR STARTER TERHADAP KARAKTERISTIK YOGHURT SARI BIT MERAH [THE VARIATION OF RED BEET (Beta vulgaris L.) JUICE RATIO, SKIM MILK, AND STARTER CULTURE TO RED BEET JUICE YOGURT] (Universitas Pelita Harapan, 2019)