Culinary spices and herbs have been used to impart a characteristic flavour and aroma in food due to their appealing fragrance. Recently, bioactive compounds from herbs, especially phenolics, have gained much attention due to their potential health outcomes. The aim of this study was to characterize and quantify the phenolic compounds from 10 widely used Australian-grown herbs (oregano, rosemary, bay, basil, sage, fenugreek, dill, parsley, mint and thyme). For this purpose, liquid chromatography mass spectrometry (LC-MS) was used for the complete profiling of polyphenolic compounds and quantification of abundant phenolic compounds was completed with high-performance liquid chromatography—photodiode array detection (HPLC-PDA). Polyphenols from Australian-grown herbs were estimated through total phenolic content (TP), total flavonoids (TF) and total tannins (TT) along with their in-vitro antioxidant activities. Oregano and mint were estimated with the highest value of TP (140.59 ± 9.52 and 103.28 ± 8.08 mg GAE/g, milligram gallic acid equivalent/gram) while rosemary and mint had the highest TF (8.19 ± 0.74 and 7.05 ± 0.43 mg QE (quercetin equivalent)/g). In this study, eighty-four (84) phenolic compounds were screened and confirmed through LC-MS/MS by comparing their masses and fragmentation pattern with published libraries. The results of this study validate the use of these herbs as bioactives and their positive impact on human health.

Bananas are an essential source of staple food and fruit worldwide and are widely regarded as the world’s largest fruit crop, with more than 100 million tons total annual production. Banana peel, a by-product that represents about 40% of the entire banana’s weight, and pulp are rich in bioactive compounds and have a high antioxidant capacity. As the production of polyphenols in fruit and vegetables is highly dependent on environmental conditions, genetic factors, and the level of maturity, this study aims to characterize six Australian banana cultivars in various stages of ripening for their phenolic compounds using the liquid chromatography-electrospray ionization quadrupole time of flight mass spectrometry (LC-ESI-QTOF-MS/MS), polyphenols quantification with the high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA), and their antioxidant capacity. All bananas were analysed for total polyphenols content (TPC), total flavonoids content (TFC), and total tannin content (TTC) and their antioxidant activities. Ripe Ducasse peel and pulp contained the highest amounts of total polyphenols content (1.32 and 1.28 mg gallic acid equivalent (GAE) per gram of sample), total tannin contents (3.34 mg catechin equivalent (CE) per gram of sample), and free radical scavenging capacity (106.67 mg ascorbic acid equivalent (AAE) per g of sample). In contrast, ripe Plantain peel had the greatest total flavonoids (0.03 mg quercetin equivalent (QE) per g of sample). On the other hand, unripe Ladyfinger pulp possessed the highest total antioxidant activity (1.03 mg AAE/g of sample). There was a positive correlation between flavonoids and antioxidant activities. By using LC-ESI-QTOF-MS/MS, a total of 24 phenolic compounds were tentatively characterized in this research, including six phenolic acids, 13 flavonoids, and five other polyphenols. Quantification of phenolic compounds by the high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) revealed a higher content of phenolic acids. These findings confirmed that banana peel and pulp have considerable antioxidant activity and can be employed in human food and animal feed for variant health enhancement uses.