Lotus seed epicarp, the main by-product of lotus seed processing, is abundant in polyphenols. In this study, polyphenols in lotus seed epicarp were separated by Sephadex LH-20 gel filtration chromatography to yield Fraction-I (F-I), Fraction-II (F-II), and Fraction-III (F-III). The polyphenol compounds in the three fractions were identified by UPLC-MI-TOF-MS. Six kinds of polyphenol compounds including cyanidin-3-O-glucoside, procyanidin trimer, and phlorizin were identified in F-I, and prodelphinidin dimer B, procyanidin dimer, and quercetin hexoside isomer were found in F-II. However, there was only procyanidin dimer identified in F-III. The in vitro antioxidant activities of the three fractions were also investigated. We found F-I, F-II, and F-III had strong potential antioxidant activities in the order of F-III > F-II > F-I. Our results suggested that polyphenols from lotus seed epicarp might be suitable for use as a potential food additive.

In this study, fresh lotus leaves at two maturity stages were processed to tea products by different methods (white-tea process, green-tea process and black-tea process). The volatile compounds, phytochemical profiles and antioxidant activities of lotus-leaf tea were investigated. A total of 81 volatile components were identified with HS-GC-IMS. The mature lotus-leaf tea showed more volatile compounds than the tender lotus-leaf tea. The lotus leaf treated with the white-tea process had more aroma components than other processing methods. In addition, six types of phenolic compounds, including luteolin, catechin, quercetin, orientin, hyperoside and rutin were identified in the lotus-leaf tea. The mature leaves treated with the green-tea process had the highest levels of TPC (49.97 mg gallic acid/g tea) and TFC (73.43 mg rutin/g tea). The aqueous extract of lotus-leaf tea showed positive scavenging capacities of DPPH and ABTS radicals, and ferric ion reducing power, whereas tender lotus leaf treated with the green-tea process exhibited the strongest antioxidant activity. What is more, the antioxidant activities had a significant positive correlation with the levels of TPC and TFC in lotus-leaf tea. Our results provide a theoretical basis for the manufacture of lotus-leaf-tea products with desirable flavor and health benefits.

Conventional lysozyme–chitosan (LCS) coatings combine the film-forming properties of chitosan with lysozyme-mediated antibacterial activity, but their antioxidant capacity and activity against Gram-negative bacteria remain limited. In this study, purified lotus leaf flavonoids (LLF) were incorporated into a LCS matrix at 0.1–0.3% (w/v) to examine how a defined flavonoid fraction affects matrix structure, film performance, and strawberry preservation under ambient storage. LLF showed strong radical-scavenging activity, with IC₅₀ values of 6.244 µg/mL for DPPH and 2.146 µg/mL for ABTS, and inhibited Staphylococcus aureus and Escherichia coli (MIC values of 0.625 and 1.25 mg/mL, respectively). Structural analyses indicated concentration-dependent, predominantly non-covalent interactions between LLF and the LCS network. LLF addition increased color intensity and opacity and altered water-related, barrier, thermal, and mechanical properties, revealing a formulation trade-off rather than uniform improvement of all material attributes. The LLF-LCS systems nevertheless showed stronger antioxidant and in vitro antibacterial activities than the CS and LCS controls. During 6 d of storage at 25 ± 2 °C, 0.2–0.3% LLF-LCS treatments reduced decay, limited weight loss, retained firmness, and better-preserved ascorbic acid, total phenolics, and anthocyanins. These findings demonstrate a formulation-dependent structure–property–preservation relationship for purified LLF in LCS coatings under short-term ambient storage and identify 0.2% LLF as the most balanced formulation within the tested range.