Pengolahan pangan dapat dilakukan pada rentang pH dari asam hingga basa. Penelitian ini bertujuan untuk mempelajari pengaruh berbagai pH pengolahan pangan terhadap aktivitas antioksidan dan total fenol ekstrak buah parijoto. Penngujian dilakukan pada pH 2, 4, 7, 8, dan 10. Analisis aktivitas antioksidan menggunakan metode aktivitas penangkapan radikal DPPH. Sedangkan analisis fenol menggunakan metode folin ciocalteu. Hasil penelitian menunjukkan bahwa perbedaan pH berpengaruh signifikan terhadap aktivitas antioksidan dan total fenol ekstrak buah parijoto. Semakin meningkat pH menyebabkan kenaikan aktivitas antioksidan dan sejalan dengan terjadinya kenaikan total fenol. Aplikasi pengolahan produk dari buah parijoto pada pH yang lebih tinggi akan menghasilkan aktivitas antioksidan dan total fenol yang cenderung lebih tinggi.

Parijoto (Medinilla speciosa) is a tropical plant that is used as traditional medicine by the community. This fruit contains many bioactive compounds. This study aims to analyze the effect of food processing temperature on the total phenolic compounds and antioxidant activity in parijoto extract. Tests are carried out at temperatures of 10, 30, 60, 75 and 100 ºC. Total phenolic compounds were analyzed by Folin-Ciocalteu method. Antioxidant activity were analyzed by DPPH (1,1-Diphenil-2-pikrilhidrazil) radical scavenging method. The results showed that the increased processing temperature causes a decrease in total phenolic compounds. This causes antioxidant activity to decrease. Processing at low temperatures is able to maintain the content of phenol compounds (33.02 μg/ml) and the greatest antioxidant activity.

Parijoto fruit (Medinilla speciosa) has a red color and contains anthocyanins. Anthocyanins have low stability due to the effect of heating. Copigmentation can be applied to improve the stability of anthocyanins. This research aims to study the effect of the anthocyanin extract from parijoto fruit ratio and copigment on anthocyanin concentration and color stability during heating at different temperatures and durations. Anthocyanin copigmentation using tannic acid in a ratio of 1:20 and 1:40 with control without copigmentation (1:0) showed that increasing the tannic acid copigment would increase anthocyanin concentrations and reduce anthocyanin losses due to increased temperature and heating time. The use of 1:40 tannic acid copigment increased anthocyanin concentration by 38%. In addition, increasing the concentration of tannic acid increased the ability of anthocyanins to maintain color retention during heating and increased temperatures. The use of tannic acid at a ratio of 1:40 only decreased color retention by 16%, compared to control (54%) after heating at 75ºC heating for 120 minutes. Copigmentation with tannic acid up to a ratio of 1:40 was able to maintain the stability of the lightness (L*), the reddish value (a*), and the yellowish value (b*) of the anthocyanins. This study showed that this system is potential for food coloring application in the food industry.