The recent millennium has witnessed a notable shift in consumer focus towards natural products for addressing lifestyle-related disorders, driven by their safety and cost-effectiveness. Nutraceuticals and functional foods play an imperative role by meeting nutritional needs and offering medicinal benefits. With increased scientific knowledge and awareness, the significance of a healthy lifestyle, including diet, in reducing disease risk is widely acknowledged, facilitating access to a diverse and safer diet for longevity. Plant-based foods rich in phytochemicals are increasingly popular and effectively utilized in disease management. Agricultural waste from plant-based foods is being recognized as a valuable source of nutraceuticals for dietary interventions. Citrus peels, known for their diverse flavonoids, are emerging as a promising health-promoting ingredient. Globally, citrus production yields approximately 15 million tons of by-products annually, highlighting the substantial potential for utilizing citrus waste in phyto-therapeutic and nutraceutical applications. Citrus peels are a rich source of flavonoids, with concentrations ranging from 2.5 to 5.5 g/100 g dry weight, depending on the citrus variety. The most abundant flavonoids in citrus peel include hesperidin and naringin, as well as essential oils rich in monoterpenes like limonene. The peel extracts exhibit high antioxidant capacity, with DPPH radical scavenging activities ranging from 70 to 90%, comparable to synthetic antioxidants like BHA and BHT. Additionally, the flavonoids present in citrus peel have been found to have antioxidant properties, which can help reduce oxidative stress by 30% and cardiovascular disease by 25%. Potent anti-inflammatory effects have also been demonstrated, reducing inflammatory markers such as IL-6 and TNF-α by up to 40% in cell culture studies. These findings highlight the potential of citrus peel as a valuable source of nutraceuticals in diet-based therapies.

Studying the multi-function bacterial implications on the natural phytochemicals could be among the best solutions for producing clean-label functional juices. This study aimed to develop a high-quality mulberry juice with enhanced antioxidant capacity through fermentation. The juice was fermented using mono- and co-cultures of Lactobacillus casei (LC), L. plantarum (LP), L. paracasei (LPC), L. acidophilus (LA), and L. helveticus (LH) at different time intervals (24, 48, 72, and 96 h). The total phenolic content (TPC), total flavonoid content (TFC), flavonols, anthocyanins, and proan-thocyanidins were determined, along with the antioxidant activity assays and FTIR analysis. The results revealed significant changes in molecular interactions and functional group presence post-fermentation, indicating microbial incorporation's effect on the juice's functional profile. These changes were attributed to the formation of new compounds during fermentation, such as organic acids, alcohols, glycerol, and phenols, as evidenced by the FTIR spectra. Besides, LC-LA and LC-LPC co-culture treatments yield the most substantial stability in TPC, TFC, and TF after 48 h compared to 24 h and 72 h. After 48 h, the co-cultures of LPC-LH (1265.5 GAE/L) and LPC-LA (1145 GAE/L) were increased the TPC after 48 h than the single cultures. Conclusively, LC-LPC and LP-LPC co-culture fermentation was recommended as a cost-effective method to enhance the an-tioxidant potential and the overall phytochemical capacity of mulberry products. The findings of this study provide valuable insights into the potential of fermented mulberry juice as a functional food with improved health benefits.