Non-fat yogurt exhibited weak body, poor texture, and whey separation because of reduction of fat. The separation of whey in yogurt is not desired by consumer. The aim of present study was to evaluate the effect of adding whey protein concentrate (WPC) and xanthan gum on physical, chemical and sensory properties of non-fat yogurt. Physical and chemical properties were tested using randomized block design whereas the yogurts properties during 21 days of cold storage included syneresis index and organoleptic. There were 6 treatments : A (full fat yogurt = control 1); B (skim milk + skim milk powder (SMP) 3% = control 2); C (skim milk + SMP 3% + WPC 1%); D (skim milk + SMP 3% + WPC 1,25%); E (skim milk + SMP 3% + WPC 0,5% + xanthan 0,005%); F (skim milk + SMP 3% + WPC 0,5% + xanthan 0,004%). The fat content 0,12%-0,14% of non-fat yogurt with the addition of WPC and blend of WPC-xanthan could increased firmness, cohesiveness and consistency compared to control 1 and control 2. In the organoleptic properties, non-fat yogurt with the addition of WPC and blend of WPC-xanthan were gained color, flavor, aroma, and consistency of the panelists preferred higher than control yogurt. Non-fat yogurt with only addition of WPC gained the lowest syneresis index. ABSTRAKYogurt tanpa lemak memiliki kekuatan struktur yang rendah dan rentan terjadi pemisahan whey karena berkurangnya kandungan lemak. Pemisahan whey pada yogurt tidak disukai oleh konsumen. Tujuan penelitian ini adalah untuk mengevaluasi efek penambahan whey protein concentrate (WPC) dan gum xanthan terhadap karakteristik fisik, kimia sensori yogurt tanpa lemak. Karakteristik fisik dan kimia diuji menggunakan metode RAK, sedangkan karakteristik yogurt selama penyimpanan dingin 21 hari meliputi indeks sineresis dan organoleptik. Terdapat 6 perlakuan yaitu: A (susu segar = kontrol 1); B (susu skim + skim milk powder (SMP) 3% = kontrol 2); C (susu skim + SMP 3% + WPC 1%); D (susu skim + SMP 3% + WPC 1,25%); E (susu skim + SMP 3% + WPC 0,5% + gum xanthan 0,005%); F (susu skim + SMP 3% + WPC 0,5% + gum xanthan 0,004%). Kandungan lemak 0,12%-0,14% pada yogurt tanpa lemak dengan penambahan WPC dan kombinasi WPC-gum xanthan dapat meningkatkan firmness, cohesiveness, dan konsistensi dibandingkan kontrol 1 dan kontrol 2. Secara organoleptik, yogurt tanpa lemak dengan penambahan WPC dan kombinasi WPC-gum xanthan mendapatkan tingkat kesukaan panelis lebih tinggi untuk warna, rasa, aroma, dan kekentalan dibandingkan yogurt lemak utuh tanpa perlakuan. Yogurt tanpa lemak dengan penambahan WPC saja mendapatkan indeks sineresis lebih rendah dibandingkan perlakuan lainnya.
Physical and chemical changes in whey protein concentrate stored at elevated temperature and humidity
