## 4 Health Benefits and Composition of Kiwi By-Products
### Kiwi Bioactives: From the Fruit's Bio-Waste to Functional Products Promoting Wellness
These findings are the result of tests involving kiwi extracts, which found increasing serum adiponectin levels and decreasing HOMA-IR, suggesting improved insulin sensitivity; meanwhile, a reduction in triglyceride accumulation in the liver was observed, and lower serum triglyceride and total cholesterol levels were reported at the same time, potentially preventing cardiovascular complications. Moreover, daraesoon (the shoot of hardy kiwi, _Actinidia arguta_) extract leads to reduced serum glucose and glycated hemoglobin levels in db/db mice, indicating improved long-term blood glucose control. Specifically, daraesoon extract reduces hepatic MCP-1 and TNF-\(\alpha\) levels in diabetic obese mice [55]. Furthermore, a study specializing in long-term colonic fermentation revealed that kiwi fruit functional groups (FFGs) positively influence gut microbial communities. While the initial effects were modest, with reductions in certain bacterial populations, metabolite analysis showed increased butyrate production. In dynamic experiments, Kiwi FFGs demonstrated a dose-dependent influence, boosting beneficial bacteria like Roseburia and A. muciniphila. Overall, Kiwi FFGs appear to have a beneficial impact on the gut microbiota [56]. In a separate survey, researchers explored the potential of _Actinitiia delicosa_ aqueous extract (ADAE) in protecting against streptozotocin-induced diabetic nephropathy, again in rats. The results demonstrate that ADAE effectively reduces oxidative stress, scavenges free radicals, and alleviates inflammation, thereby improving renal function and mitigating lipid peroxidation-related damage. ADAE's potent antioxidant and anti-radical properties contribute to lowering blood glucose levels and mitigating changes in hematological parameters, renal function biomarkers, kidney tissue structure, and gene expression affected by lipid peroxidation. These findings underscore ADAE's potential as a therapeutic agent for preventing and treating diabetic nephropathy, offering hope for individuals seeking natural remedies for diabetes-related complications [57]. Special attention should be directed to an attempt that was carried out experimentally to enhance the stability and bioavailability of polyphenol-rich kiwi extracts--purified kiwi leaf proanthocyanidins (PKLPs)--by ultrasound-assisted nanoencapsulation. Various factors, such as lecithin mass ratios, ultrasonic power and time, the storage conditions, and simulated gastrointestinal digestion, play crucial roles in modulating the properties of nanoliposomes loaded with PKLPs. Higher lecithin mass ratios were apparent, albeit enhancing encapsulation efficiency, resulting in larger particle sizes and reducing the stability. Ultrasonic treatment can improve nanoliposome stability and homogeneity, enhancing the bioavailability of PKLPs. Moreover, in vitro digestion studies indicate altered nanoliposome properties and improved bioaccessibility of PKLPs, with in vivo studies demonstrating enhanced plasma concentration and bioavailability. However, it is noteworthy that the antioxidant capacity of loaded nanoliposomes is lower compared to free PKLPs, suggesting potential formulation challenges [58]. As mentioned in the third chapter, the utilization of kiwi fruit residues has garnered attention for its rich phenolic content, with 10 phenolics identified, encompassing benzoic acids, cinnamic acids, flavan-3-ols, and flavonoids. Notably, caffeic acid emerged as the predominant phenolic compound, followed by p-hydroxybenzoic acid, epicatechin, ferulic acid, and catechin. These five key phenolics collectively constitute 86% of the total identified phenolics in kiwi fruit pomaces [59]. Further exploration into kiwi seed polyphenols (KSPs) revealed strong antioxidant and anti-inflammatory properties, attributed to the synergistic effects of the five identified polyphenic compounds. Notably, KSPs exhibited superior radical scavenging activity compared to synthetic antioxidants, showcasing their potential for suppressing the expression of pro-inflammatory cytokines.