Impact of Lactic Acid Bacteria Fermentation on Phenolic Compounds and Antioxidant Activity of Avocado Leaf Extracts

Abstract

The growing global consumption of avocados, associated with contents including bioactive compounds with numerous health-promoting properties, is producing a large amount of agro wastes around the world. Different management approaches are available for the recovery of bioactive compounds from wastes as potential ingredients for use in the production of functional foods and nutraceuticals. Lactic acid fermentation can be used to exploit nutritional potential and add value to agro wastes. In this study, fermentations with lactic acid bacteria were carried out in avocado leaves, and the total phenolic content and the antioxidant activity were determined by DPPH and FRAP assays from hydroalcoholic extracts obtained from fermented avocado leaves. Fifteen new phenolic compounds were identified for the first time in avocado leaves by HPLC-ESI-TOF-MS. L. plantarum CECT 748T and P. pentosaceus CECT 4695T showed the highest antioxidant activity. The sum of phenolic compounds was increased by 71, 62, 55 and 21% in fermentations with P. pentosaceus CECT 4695T, L. brevis CECT 5354, P. acidilactici CECT 5765T and L. plantarum CECT 9567, respectively, while it was reduced in the fermentation with L. plantarum 748T by 21% as demonstrated by HPLC-ESI-TOF-MS. Biotransformations induced by bacterial metabolism modified the phenolic compound profile of avocado leaves in a strain-specific-dependent manner. P. pentosaceus CECT 4695T significantly increased kaempferol, P. pentosaceus 4695T, L. brevis 5354 and L. plantarum 9567 increased rutin, and dihydro-p-coumaric acid was increased by the five selected lactic acid bacteria. Total flavonoids were highly increased after fermentations with the five selected lactic acid bacteria but flavonoid glucosides were decreased by L. plantarum 748T, which was related to its higher antioxidant activity. Our results suggest that lactic acid bacteria led the hydrolysis of compounds by enzymatic activity such as glycosidases or decarboxylase and the release of phenolics bound to the plant cell wall, thus improving their bioavailability.

Effect of Lactic Acid Bacteria Fermentation on the Polar Compounds Content with Antioxidant and Antidiabetic Activity of Avocado Seed Extracts

“…The fermentation of avocado seeds by LAB could lead to several benefits, such as improving their bioactivities, a field of research that has not been deeply studied. In avocado leaves, the fermentation by LAB has led to satisfactory results [13]. Recently, Rozan et al reported a reduction in the anti-nutrients tannins, oxalates, and alkaloids contents of 80.76%, 89.95%, and 70%, respectively, by fermenting avocado seed with LAB [14].…”

“…Based on the above and the results obtained in previous research [13], this study aimed to evaluate the effect of submerged fermentation with different LAB on the polar profile of avocado seeds, evaluating the antioxidant and the antidiabetic activities, in comparison to an unfermented avocado seed extract.…”

Avocado leaf‐waste management: drying technology and quality of leaf herbal teas of different varieties cultivated in the Mediterranean area

“…In the context of a circular economy and considering the number of bioactive compounds present in the avocado leaves, it could be of great interest to use the avocado leaf wastes as a raw material to high-value food products. Recently, De Montijo-Prieto et al (2023) proposed the use of avocado leaf waste for the extraction of bioactive compounds; anyway, their use as raw material for high-value food products could be more environmentally sustainable.…”

“…Recently, De Montijo‐Prieto et al . (2023) proposed the use of avocado leaf waste for the extraction of bioactive compounds; anyway, their use as raw material for high‐value food products could be more environmentally sustainable.…”

Anti-oxidant and immune enhancement effects of Artemisia argyi H. fermented with lactic acid bacteria

“…The fermented kimchi is known for a high levels of lactic acid bacteria, has investigated the many health beneficial effects such as antioxidant, anticancer, and antiobesity [14]. A study has also reported that the fermentation of avocado leaves by lactic acid bacteria exhibited higher antioxidant activities [15]. Therefore, many studies focus on the immune improving effects of natural products to develop functional materials from food sources using lactic acid bacteria fermentation.…”