Xiao-Hua Dai

Large-fruited hawthorn (Malus doumeri (Bois) Chev.) is valued for its health-promoting properties, largely attributed to its rich flavonoid content. However, little is known about the specific composition of flavonoids and the molecular mechanisms regulating their biosynthesis. The present study employed non-targeted metabolomic and transcriptomic approaches to investigate two M. doumeri germplasms (G8 and G9) that exhibited significantly different total flavonoid contents. The results indicated that the major and differential metabolites primarily include flavonoids and isoflavonoids. Differentially expressed genes were significantly enriched in phenylpropanoid and flavone and flavonol biosynthesis pathways. Integrated analysis identified several structural genes and transcription factors, including HCT (LOC114821133, LOC103403337, LOC103454980), WRKY (LOC103427630), and bHLH (LOC103422512), that were significantly upregulated in the high-flavonoid genotype (G9). qRT-PCR validation confirmed the RNA-Seq expression patterns, suggesting the potential involvement of these genes in the biosynthesis of phenylpropanoid-related metabolites, such as [6]-gingerol. Applied experiments further demonstrated that freeze-drying preserved high metabolite contents and antioxidant activity. Collectively, these findings provide insights into the compositional characteristics of the major flavonoids in M. doumeri and the biosynthesis of phenylpropanoid-derived metabolites. This study provides data support for future mechanistic validation and evaluation of processing technology applicability.

Fructooligosaccharides (FOS) represent a major source of prebiotic compounds. They are widely used in functional foods for their ability to modify intestinal microbiota in animals and humans. To address the significant issue of fructooligosaccharide production being influenced by glucose concentration, this study designed a dual-enzymatic co-catalysis system for glucose isomerase (GI) and a mutant FTase (FTase^142P-242K). This system successfully increased the FOS synthesis rate (42.31 to 55.51%, w/w). Glucose isomerase catalyzes the isomerization of glucose to fructose, and the subsequent release of fructose from the active site permits the enzyme to re-enter its catalytic cycle. The optimal conditions for catalysis were found at 45 °C, pH 5.5, and 1 mM Ba²⁺. In contrast, the optimal fermentation process was established at 25 °C and induction with 1 mM IPTG. Finally, the efficient production of FOS using low-cost byproduct molasses was achieved. Fermentation optimization of the dual-enzyme system resulted in FOS yield of 53.92% (w/w), a significant increase (44.54%, w/w) from the yield obtained using single-enzyme catalysis. Based on the research, a novel and sustainable approach for high-yield synthesis of Fructooligosaccharides involves minimizing the inhibitory effect of glucose produced during sucrose transformation.

The quality of different coffee varieties varies, and the corresponding bioactive value of coffee processing byproducts is often overlooked. For that, we employed HPLC, GC-MS, and electronic sensory analyses to evaluate the key bioactive components, antioxidant potential, and flavor traits of green coffee bean and coffee processing byproducts of seven coffee varieties. The results showed that green coffee beans (Oe+Ie) and exocarp (Ep) possessed strong antioxidant activity and high total phenolic content (TPC), caffeine and trigonelline content. Among the varieties, DR390 contained higher levels of total phenols, caffeine, and trigonelline, whereas DR402 was rich in caffeine and chlorogenic acid. In addition, RY3 exhibited higher TPC, total flavonoid content (TFC), caffeine, and chlorogenic acid. The parchment (Pc) layer was rich in soluble sugars (1.83–5.43%), while the silverskin (Sk) contained relatively high levels of chlorogenic acid (3.58–4.69 mg/g). Flavor analysis identified eleven classes of volatile compounds in green coffee bean (Oe+Ie) and byproducts (Ep, Pc, Sk), with esters, ketones, alcohols, and aldehydes being the most prevalent. Seven key aroma compounds, including methyl salicylate, phenethyl alcohol, nonanal, and benzaldehyde, were identified across the various structural tissues of coffee fruit. Distinct flavor profiles were observed among the coffee fruit parts: green coffee bean (Oe+Ie) was nutty; the Ep showed fruity and cocoa-like aromas; the Pc and Sk exhibited papery and nutty aromas, respectively. Varieties DR397, DR402, and RY3 exhibited pronounced aroma profiles. Comprehensive analysis showed that DR402 and RY3 had higher overall scores for bioactive and flavor components than other varieties in their groups. In summary, green coffee bean (Oe+Ie) exhibited strong antioxidant activity and high levels of bioactive compounds. Coffee byproducts, such as the Ep, hold potential for extracting natural antioxidants and bioactive compounds to develop specialty products or for other high-value utilization.

Hawthorn is widely distributed across China, including Shanxi, Henan, Hebei, Shandong, and Shaanxi provinces. It is rich in functional components and nutritional elements, making it a crucial raw material for medicinal and food products. This review provides comprehensive information of the distribution of hawthorn germplasm resources in China and compares the differences in nutrient composition, chemical substances, and functional activities among different species. Furthermore, it offers a statistical analysis of the diversified processing and applications of hawthorn in China. Finally, the review identifies current challenges in the agro-food industries and states the future outlook of the industry. By systematically integrating research findings into a comprehensive “resource–characterization–application” framework, the study addresses the current fragmentation and lack of systematic organization in hawthorn research. It seeks to provide a scientific basis for directional breeding, strategic planning of production areas, precise product development, and high-quality development of the hawthorn industry in years to come.

Averrhoa carambola L. (family Oxalidaceae), known as star fruit, is a berry species found in tropical and subtropical regions, recognized for its unique crisp texture, high juiciness, and refreshing, slightly tangy flavor profile. A. carambola is known for its relatively high total oxalate content (fresh weight: 200–1840 mg/100 g), and excessive consumption is linked to toxicity, particularly in individuals with chronic kidney disease or other renal disorders. Therefore, understanding the mechanisms behind oxalate accumulation is crucial for developing effective strategies to manage oxalate levels in A. carambola . To our knowledge, this represents the first comprehensive transcriptomic investigation conducted across distinct fruit types of A. carambola . Results demonstrated that the downregulation of genes associated with oxalate oxidation contributes to the elevated oxalate content observed in sour-type A. carambola fruits. In addition, L-ascorbate concentration exhibits a positive correlation with oxalate levels across different varieties. These findings establish a foundational work for formulating rational and targeted strategies to regulate oxalate content in A. carambola , encompassing genetic improvement, optimized harvest timing, and carefully designed post-harvest management practices.