Essential oil of black pepper (Piper nigrum) and cardamom (Amomum sublatum roxb) as a natural food preservative for plum RTS

Ready-to-serve (RTS) drinks and fruit juices are crucial due to their high calorie, fiber, and vitamin content. However, their limited shelf life and rapid nutrient loss raise food safety concerns. Applied artificial preservatives may be allergic and cause adverse health effects on humans; consequently, worldwide concern about using natural preservatives instead of artificial ones. This study's main focus is to replace artificial preservatives by applying essential oils from black pepper (Bp) and cardamom (Cd) as natural preservatives in plum RTS drinks. The essential oil was extracted by hydro-distillation using a Clevenger type apparatus and stored at 4 to 6 °C. Following, plum juice was extracted by a screw press juice extractor and afterward maintained at 0.3 % acidity and 15°-brix (°Bx) total soluble solid (TSS), finally, pasteurized at 90 °C for 10 min and stored at refrigeration temperature. After preparation of RTS, it was divided into four equal batches of 250 cm3 with no additives (A), 0.100 cm3 ethanol (B), samples C and D were prepared with 0.090 cm3 of ethanol and 0.010 cm3 of essential oils of Bp and Cd. The samples were stored at a refrigerated temperature of 4 to 6 °C and analysis of pH, % titratable acidity, mg of ascorbic acid, TSS, % total sugar, % reducing sugar, free radical scavenging activity (%RSA), total microbial count, and yeast-mold count were carried out at a fixed interval of 7 days for 28 days. Overall, significant variations were observed in the blank sample compared with the sample containing the essential oils of Bp and cardamom Cd during the storage period of 28 days. These findings highlighted valuable insights into the essential oils of Bp and Cd exhibit the preservative effect in plum RTS; ultimately, cardamom essential oil exhibits the best preservative effect on plum RTS.