We previously reported that Citrus kawachiensis peel is abundant in auraptene (AUR), 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF), nobiletin (NBT), naringin (NGIN), and narirutin (NRTN). All of the above are known as citrus functional components, and a part of these is extracted from the peel into the juice during fruit squeezing. In the present study, we demonstrated that while squeezing method did not affect the composition of compounds in the juice, the contents were affected. Heat treatment for a longer duration led to AUR decomposition, while HMF, NBT, NGIN, and NRTN did not decompose. These 5 components were stable in hot ethanol after 24 h.
Ishizuchi-kurocha is a postfermented tea produced in Saijo, Ehime, Japan. Harvested tea leaves are fermented aerobically by fungi. Subsequently, the tea leaves are fermented anaerobically by lactic acid bacteria. In the current study, fermentation-related lactic acid bacteria were examined during the processing of Ishizuchi-kurocha obtained from three producers over a period of 3 years. Lactobacillus plantarum subsp. plantarum was isolated as the dominant species in Ishizuchi-kurocha. Lactobacillus brevis was also frequently isolated. In contrast, none of these species could be isolated from raw tea leaves. A component analysis of the tea extract was performed. The amount of catechins, amino acids, and γ-amino butyric acid in tea leaves changed during anaerobic fermentation. L. plantarum was selected during aerobic fermentation and grew exponentially during anaerobic fermentation. And L. brevis is important for GABA formation. Our results suggest that a controlled growth of L. plantarum is essential for the processing of the Ishizuchi-kurocha. Practical applications In the present study, we revealed dynamics of lactic acid bacteria during fermentation of Japanese postfermented tea. Optimization of fermentation process is important for stable and safety processing of the postfermented tea. Good growth of Lactobacillus plantarum subsp. plantarum and Lactobacillus brevis is important for flavor, taste, and function of the postfermented tea. Our work contributes to stable and efficient processing of the traditional postfermented tea.
In this study, an optimal watering scheduling that improves the quality of Satsuma mandarin grown in the field was investigated using an intelligent control technique combined with neural networks and genetic algorithms. The monthly data on fruit responses and climate factors were collected from August to November over 1996-2004. Dynamic changes in the sugar and citric acid contents of Satsuma mandarin, as affected by rainfall and sunshine duration, was first identified using neural networks, and then an optimal watering scheduling (rainfall management) that maximizes the sugar content and that minimizes the citric acid of Satsuma mandarin was determined through simulation of the identified neural-network model using genetic algorithms. The optimal value obtained was a combination of the marked increase in watering during the fruit-developmental stage (August and September) and a significant decrease in watering during the fruit-maturing stage (October and November) . From model simulation, a marked increase in watering during the former stage induced a lower citric acid content, and a significant decrease in watering during the latter stage induced an increase in sugar content. Drip irrigation is commonly used for increasing watering whereas plastic-film mulching is used for reducing it.
Cerebral ischemia/reperfusion leads to delayed neuronal cell death, resulting in brain damage. Auraptene (AUR) and naringin (NGIN), which exert neuroprotective effects in ischemic brain, are abundant in the peel of Citrus kawachiensis. Although parts of AUR/NGIN are transited from the peel to the juice during the squeezing of this fruit, these amounts in juice might be too low to exert effects. We thus prepared the AUR/NGIN-rich fruit juice of C. kawachiensis by addition of peel paste to the raw juice. The present study revealed that orally administration of the dried powder of this AUR/NGIN-rich fruit juice (2.5 g/kg/d) for 7 d to ischemic mice significantly suppressed the ischemia-induced neuronal cell death in the hippocampus, which was coincidently with the reduction of hyperactivation of microglia and astrocytes. These results suggest that AUR/NGIN-rich juice of C. kawachiensis may possess therapeutic potential for the prevention of neurodegenerative diseases via inhibition of inflammatory processes.
The elderly experience numerous physiological alterations. In the brain, aging causes degeneration or loss of distinct populations of neurons, resulting in declining cognitive function, locomotor capability, etc. The pathogenic factors of such neurodegeneration are oxidative stress, mitochondrial dysfunction, inflammation, reduced energy homeostatis, decreased levels of neurotrophic factor, etc. On the other hand, numerous studies have investigated various biologically active substances in fruit and vegetables. We focused on the peel of citrus fruit to search for neuroprotective components and found that: 1) 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF) and auraptene (AUR) in the peel of Kawachi Bankan (Citrus kawachiensis) exert neuroprotective effects; 2) both HMF and AUR can pass through the blood–brain barrier, suggesting that they act directly in the brain; 3) the content of AUR in the peel of K. Bankan was exceptionally high, and consequently the oral administration of the dried peel powder of K. Bankan exerts neuroprotective effects; and 4) intake of K. Bankan juice, which was enriched in AUR by adding peel paste to the raw juice, contributed to the prevention of cognitive dysfunction in aged healthy volunteers. This review summarizes our studies in terms of the isolation/characterization of HMF and AUR in K. Bankan peel, analysis of their actions in the brain, mechanisms of their actions, and trials to develop food that retains their functions.
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