Antioxidants are important inhibitory compounds against the oxidative deterioration of food. This study investigated the effects of various phytochemical antioxidant systems [oleoresin rosemary (OR), oleoresin sage (OS) and citric acid (CA)] on the physico-chemical characteristics of refined, bleached and deodorized (RBD) palm olein during the frying of potato chips. The effects of various mixtures of the antioxidants on the oil was also studied in repeated deep frying. The response surface methodology was used to optimize the composition of mixed antioxidants used. A comparative study was carried out with synthetic antioxidants. Samples of the oil after frying were analyzed for different physical and chemical properties. OR and OS were found to be effective phytochemical antioxidants protecting RBD palm olein against oxidative deterioration during frying.
Rosmarinic acid is a bioactive phytochemical that can be found in many herbs as ethnomedicines. It possesses remarkable pharmacological activities, and thus leading to its exploration as a therapeutic drug in diabetes treatment recently. This article reviews the extraction and fractionation techniques for plant-based natural rosmarinic acid and its anti-diabetic potential based on literature data published in journals, books, and patents from 1958 to 2017. Factors affecting the performance of rosmarinic acid extraction and fractionation such as operating temperature, time, solvent to sample ratio and eluent system are compiled and discussed in detail. The inhibitory action of rosmarinic acid against sugar digestive enzymes, and protective action towards pancreatic β-cell dysfunction and glucolipotoxicity mediated oxidative stress are also critically reviewed. The optimal parameters are largely dependent on the applied extraction and fractionation techniques, as well as the nature of plant samples. Previous studies have proven the potent role of rosmarinic acid to control plasma glucose level and increase insulin sensitivity in hyperglycemia. Although rosmarinic acid is readily absorbed by human body, its mechanism after consumption is remained unclear. Intensive studies should be well planned to determine the dosage and toxicity level of rosmarinic acid for efficacy and safe consumption.
The objective of this study was to determine the effects of dietary supplementation of Nigella sativa L. seeds, Rosmarinus officinalis L. leaves and their combination on rumen metabolism, nutrient intake and digestibility, growth performance, immune response and blood metabolites in Dorper lambs. Twenty-four entire male Dorper lambs (18.68 ± 0.6 kg, 4-5 months old) were randomly assigned to a concentrate mixture containing on a dry matter basis either, no supplement (control, T1), 1% R. officinalis leaves (T2), 1% N. sativa seeds (T3) or 1% R. officinalis leaves +1% N. sativa seeds (T4). The lambs had ad libitum access to urea-treated rice straw (UTRS) and were raised for 90 days. Supplemented lambs had greater (P