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Item White mulberry leaf (Morus alba L.) infusion as a strategy to reduce starch digestibility: The influence of particle size of leaf powder(Elsevier B.V., 2024-10-30) Aumasa T; Apinanthanuwong G; Singh J; Kaur L; Tian J; Phongthai S; Tanongkankit Y; Issara U; Ogawa Y; Donlao NMulberry leaf (Morus Alba L.) has been found in clinical trials to be effective in reducing diabetes in Asia. The powdered tea market is expanding in popularity due to its functional properties. This study aimed to examine the influence of different particle sizes of mulberry leaf powder (MLP) infusion on the digestibility of starch in cooked Japonica rice (cv. Koshihikari) and the bioaccessibility of phytochemicals. Dried mulberry leaf was pulverized and sieved into several particle sizes: 160 μm (MLP160), 250 μm (MLP250), 404 μm (MLP404), and 774 μm (MLP774). Through simulated in vitro digestion, we assessed starch hydrolysis (%SH), the kinetics of starch hydrolysis, estimated glycemic index (eGI), as well as total phenolic content (TPC) and total flavonoid content (TFC). The smaller particle size of MLP showed a greater reduction of eGI. Specifically, infusions prepared from MLP160 resulted in a reduction of 15 % in eGI for cooked grains and 3 % for slurries, respectively. The reduction in eGI was attributed to the interaction among flavonoids and digestive enzymes, demonstrating a concentration-dependent manner on enzyme inhibition effect. Pulverization significantly influenced the concentration of phytochemicals and their bioaccessibility in infusions. This study offers valuable insights into determining optimal particle sizes for MLP, considering both physical and functional characteristics as well as implications for the food industry. The results further suggest that MLP infusion holds promise as a functional beverage, potentially providing benefits in reducing postprandial hyperglycemia.Item The role of herbal teas in reducing the starch digestibility of cooked rice (Oryza sativa L.): An in vitro co-digestion study(Elsevier GmbH on behalf of Society of Nutrition and Food Science e.V, 2023-11-01) Aumasa T; Ogawa Y; Singh J; Panpipat W; Donlao NHerbal teas are well known for their antidiabetic effects due to the abundance of phenolic acids, flavonoids, and tannins. An in vitro co-digestion test was conducted to observe influence of herbal teas (HTs) i.e., beal fruit (BA), mulberry leaf (MB), gymnema leaf (GM), and chrysanthemum flower (CS) on starch digestibility of cooked rice and to elucidate correlation analysis of phytochemicals and their antioxidant activities during in vitro starch hydrolysis (SH). HTs prepared from GM and MB showed highest reduction of SH, kinetic constant and estimated glycemic index (eGI) of cooked rice, followed by BA and CS. Besides, MB and GM teas decreased the eGI of cooked rice up to 15%, followed by BA and CS teas, respectively. Phytochemicals and their antioxidant activities were positively correlated to SH, with both parameters displaying a higher decrease in intestinal phase when compared to gastric phase during in vitro co-digestion. These results indicate a strong interaction among phytochemicals and α-amylase in influencing glycaemic parameters. Thus, HTs has the potential to provide functional health benefits in lowering postprandrial hyperglycemia.Item Investigating the health benefits of Monty’s Surprise apple phytochemicals : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatū, New Zealand. EMBARGOED until 18 November 2027.(Massey University, 2024) Nezbedová, LindaCancer is a major health concern worldwide, requiring effective prevention strategies to reduce its burden. There is evidence suggesting that diet plays an important role in disease prevention. Apples are an example of a commonly available fruit that can be easily incorporated into a diet to reduce the risk of chronic disease and some cancers. Apples are rich in phytochemicals with chemo-preventative properties. However, assessing their benefits in humans is complex due to various factors affecting phytochemical composition and low bioavailability. Understanding and controlling for these factors is crucial for maximising their potential in preventing cancer and promoting human health. The PhD project presented in this thesis uses a multidisciplinary ‘from orchard to fork to function’ approach to evaluate the health benefits of phytochemicals in a New Zealand heritage apple cultivar known as Monty’s Surprise, with an emphasis on cancer prevention. This thesis particularly focuses on apple’s most abundant phytochemical group known as phenolic compounds. After controlling fruit harvest and maturity, Monty’s Surprise apple was found to contain high concentrations of health beneficial phenolics, especially procyanidins, with apple skin having higher total phenolic content compared to its flesh. Pureeing was identified as a suitable processing technique with minimal impact on apple’s phenolics, allowing long-term preservation and creating uniform material for use in intervention and feeding trials. Moreover, Monty’s Surprise apple extract depleted of sugars inhibited the proliferation of lung, breast, and colorectal cancer cells in a dose-dependent manner in vitro. Lastly, in a human acute feeding trial, Monty’s Surprise apple puree increased plasma antioxidant capacity and decreased postprandial glucose response compared to sugar-matched placebo. The feeding trial also showed that procyanidins were not detected in the participant’s blood, while epicatechin and chlorogenic acid, which are prevalent phenolics in Monty’s Surprise apple puree, were absorbed into the bloodstream. Therefore, these compounds were available to contribute to the improved health parameters measured in the study. This study offers practical recommendations for optimising harvesting, storage, and processing practices to preserve and more clearly elucidate the health-promoting properties of phenolics in apples. Overall, this research demonstrated the potential health benefits of Monty’s Surprise apple and its phenolics, suggesting its value as a functional food for improving human health and well-being.Item Exploring efficient extraction methods: Bioactive compounds and antioxidant properties from New Zealand damson plums(Elsevier Ltd, 2023-10) Xia P; Ahmmed MK; Rashidinejad AThe study determined the best extraction method for phenolic compounds (rutin, catechin, epicatechin, naringenin, neochlorogenic acid, and rosmarinic acid) in the New Zealand damson plums. Accelerated solvent extraction (ASE) using ethanol and water was used to evaluate the solvent efficacy. Further comparisons were made among ASE, ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and a combined method (E + UAE) using water as the solvent. The findings showed that ASE for 40 min was the most effective method for extracting phenolic compounds (1.76 mg gallic acid equivalent/g) compared to other methods (UAE = 1.17, EAE = 1.3, and E + UAE = 1.45 mg/g). The ASE method also resulted in an extract with a higher antioxidant activity than other methods. The extraction time over 40 min decreased the yield regardless of the solvent used. Therefore, the ASE extraction method for 40 min is recommended as the best method for extraction of phenolic compounds from the New Zealand damson plums.Item Onco-Preventive and Chemo-Protective Effects of Apple Bioactive Compounds(MDPI (Basel, Switzerland), 2021-11) Nezbedova L; McGhie T; Christensen M; Heyes J; Nasef NA; Mehta SCancer is one of the leading causes of death globally. Epidemiological studies have strongly linked a diet high in fruits to a lower incidence of cancer. Furthermore, extensive research shows that secondary plant metabolites known as phytochemicals, which are commonly found in fruits, have onco-preventive and chemo-protective effects. Apple is a commonly consumed fruit worldwide that is available all year round and is a rich source of phytochemicals. In this review, we summarize the association of apple consumption with cancer incidence based on findings from epidemiological and cohort studies. We further provide a comprehensive review of the main phytochemical patterns observed in apples and their bioavailability after consumption. Finally, we report on the latest findings from in vitro and in vivo studies highlighting some of the key molecular mechanisms targeted by apple phytochemicals in relation to inhibiting multiple ‘hallmarks of cancer’ that are important in the progression of cancer.Item Reduction of the attachment, survival and growth of L. monocytogenes on lettuce leaves by UV-C stress(Elsevier Ltd, 2021-06) Kyere EO; Popovich DG; Palmer J; Wargent JJ; Fletcher GC; Flint SMild stress of leafy greens by UV-C radiation has been reported to stimulate plant defences capable of reducing pathogens on produce surfaces. In this study, the attachment, survival and growth of Listeria monocytogenes was investigated on lettuces stressed with mild UV-C radiation (1.3 and 2.6 kJm−2). Attachment of L. monocytogenes to UV-C stressed (1.3 kJm−2) lettuce leaves after 1 h was significantly (p < 0.05) reduced by 1.4–1.5 log cfu/cm2. UV-C stress also reduced the survival of L. monocytogenes on lettuce by 1.8–1.9 log cfu/g 96 h after inoculation, however a higher dosage of UV-C stress (2.6 kJm−2) did not inhibit the survival of L. monocytogenes. The total phenolic compounds in lettuce significantly increased following UV-C stress (1.3 kJm−2) indicating the accumulation of polyphenols might have contributed to the inhibition of L. monocytogenes attachment and growth. Appropriate dosage of mild UV-C stress of lettuce can reduce the attachment, survival and growth of L. monocytogenes in lettuce and can therefore be explored further for application in fresh produce safety.Item Fruit modulation of the effects of fatigue on cognitive performance : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Psychology at Massey University, Albany, New Zealand(Massey University, 2018) Peart, NatalieCognitive fatigue hinders performance in social, academic and physical environments and has a profound effect on the ability of a person to function and make decisions. Research into reducing or eliminating cognitive fatigue and its effects have been largely inconclusive but an emerging area of research is focussing on phytochemicals effects on optimising cognition. The present study examined the effects of blackcurrant supplementation on cognitive fatigue and physical markers of performance. This required 11mg of freeze-dried blackcurrant powder and water mixture to be consumed by participants before completing a psychometric and exercise test. Blackcurrants are a high source of phytochemicals but are under-researched compared to other berry fruit, such as blueberries. Sixty participants completed two sessions which composed of a familiarisation session and an intervention session. Participants were randomly assigned to the blackcurrant supplementation or the control group. Each session consisted of six blocks of the Stroop test, a Standard VO2max test and followed by a post-exercise Stroop test. The purpose of the Standard VO2max test to exhaustion was to induce physical and cognitive fatigue. At the intervention session, participants ingested either a blackcurrant or sugar-controlled juice one hour before testing. Analyses demonstrated that the blackcurrant supplement had no effect on cognitive performance or physical markers. However, it was questionable as to whether the study had enough statically power to test for the small effect sizes due to participants being unable to complete testing and some data sets unable to be used. Future research should focus on larger sample sizes and high doses of anthocyanin to observe if blackcurrant can have cognitive and physiological effects.Item Mitigation of the impact of cognitive fatigue on simple motor performance by phytochemicals : the effect of a blackcurrant supplement : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University, Manawatū, New Zealand(Massey University, 2014) Ratlidge, RebeccaCognitive fatigue can be brought on by prolonged periods of demanding cognitive activity which has been found to impair both cognitive and physical performance. Phytochemical supplementation can result in improvements in both cognitive and physical performance. However, the ability for phytochemical supplementation to reduce the effects cognitive fatigue has on subsequent physical performance has not been investigated. Therefore, the present study examined the effects that phytochemicals from a blackcurrant supplement had in reducing the effects of cognitive fatigue on simple motor performance. Sixty healthy participants completed 75 minutes of a vigilance task (cognitive fatigue) or 75 minutes of watching an emotionally neutral documentary (control). Half of the participants in each condition also received a blackcurrant supplement (3.2mg/kg) 1 hour before beginning the experimental session. Following the 75 minutes of time-on-task participants completed mood and motivation questionnaires as well as four motor tasks. Analyses revealed the vigilance task was successful in inducing cognitive fatigue, but this had little effect on subsequent motor performance compared to controls. Further analyses revealed the blackcurrant supplement had little influence on either cognitive or motor performance, although the lack of an effect of cognitive fatigue on motor performance made this finding difficult to interpret. Effect size calculations indicated that a larger sample would have likely resulted in statistically significant findings for the majority of the motor tasks. It is concluded that for the specific tasks used in the present study, cognitive fatigue did not impair subsequent motor performance. Nor did the blackcurrant supplement, at the dose used, enhance motor performance following cognitive fatigue. Possible explanations for these findings are discussed and some potentially useful future studies outlined.Item The amelioration of the impact of physical fatigue on cognitive performance by phytochemicals : a thesis presented in partial fulfillment of the requirements for the degree of Master of Arts in Psychology at Massey University, Manawatu, New Zealand(Massey University, 2016) McKenzie, OliviaFatigue is common in everyday life. It is experienced as either cognitive or physical fatigue, both of which are intertwined. Researchers are interested in investigating the ability of phytochemical supplementation to improve cognitive performance by diminishing the effects of physical fatigue. The results thus far have been highly inconsistent (Brisswalter & Arcelin, 1997). The present study examined the effects of phytochemical supplementation utilising a daily dose of 240 mg of blackcurrant extract, a berry fruit high in phytochemicals but under-researched compared to other berry fruits, such as blueberries. Fifty healthy participants completed two 3-hour trials, the first during Week 1 and the second 6 weeks later. Half of the participants were randomly assigned to the blackcurrant supplement group, the supplement being consumed each day over the 6-week period. Each trial consisted of five cognitive tests followed by a tailored HIIT cycle test. The purpose of the HIIT was to induce physical fatigue and took less than 10 min overall. Cognitive tasks and mood questionnaires were completed pre and post consumption of the supplement at both Week 1 and Week 6. Participants received the blackcurrant supplement 1 hour before post task measurements were completed. Analyses demonstrated that the blackcurrant supplementation had no influence on cognitive performance. However, it is questionable as to whether the degree of physical fatigue induced was sufficient to negatively influence cognitive performance, even though previous studies had found it to be so. Overall, it was concluded that blackcurrant supplementation taken across 6 weeks did not facilitate cognitive performance after physical fatigue. Possible explanations for these findings are discussed, including ways for future research to move forward.Item Phytochemical-rich potato extracts and potential for risk reduction in tamoxifen treatment of breast cancer : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Palmerston North, New Zealand(Massey University, 2013) Chong, Esther Swee LanExisting data suggest an inverse correlation between breast cancer risk and vegetable consumption, and the anticancer effects of vegetables are attributed to the diversity and abundance of phytochemicals. Standard endocrine therapies for breast cancer are associated with significant side effects and not always effective. Undoubtedly, there is a need for improved treatment of breast cancer. In the quest for better breast cancer treatments with fewer side effects, food and nutrition represent a logical strategy to explore. Potato (Solanum tuberosum L.) was chosen for the present project as the target vegetable for investigation. Pigmented potato has recently attracted research attention because of its potential health benefits. Two potato extracts were prepared from a white and purple variety (‘Urenika’) and referred to as WPE and PPE respectively. Tamoxifen and estradiol exhibited paradoxical effects: each of them was inhibitory at high doses but stimulatory at low to moderate doses, on proliferation of two breast cancer cell lines, MCF-7 and T-47D. In contrast, both PPE and WPE inhibited cell proliferation in a dose-dependent manner without paradoxical effects. The potato extracts also blocked estradiol- or tamoxifeninduced cell proliferation of these two cell lines. These findings imply that both potato extracts may have a role to play in prevention of breast cancer, or complementing tamoxifen to achieve desirable treatment efficacy. Since both PPE and WPE were equivalent in efficacy, one (PPE) was selected for further study, given the intention of developing a nutraceutical or therapeutic product of New Zealand proprietary value. Phytochemical compositions of the potato extracts were identified and quantified using ultra high performance liquid chromatography-mass spectrometry, many of which were reported for the first time in variety ‘Urenika’. Several compounds were found at doses which have been reported individually to exert bioactive effects against cancer. It is possible the antiproliferative effects of potato extracts resulted from more than one of these bioactive compounds working together. Dose-dependent apoptotic effects of PPE were observed in T-47D culture, and a combined effect seems to exist between PPE and tamoxifen in modulating the S and G2/M phase. In summary, the key contributions and significance of current thesis are: (1) demonstration of the “risk” zone for tamoxifen (10-8 to 10-6 M) and estradiol (10-10 to 10-8 M) concentrations which may stimulate breast cancer cell growth. Note that these concentrations of tamoxifen or estradiol are physiologically achievable. Furthermore, one key novel finding is regarding the estradiol dependency of tamoxifen action. Specifically, at low to moderate doses (10-9 to 10-8 M) of tamoxifen, there is a threshold of estradiol (> 10-8 M) which allows a significant inhibitory action to occur. The stimulatory action of tamoxifen and complex interaction between tamoxifen and estradiol observed in vitro may partially explain the failure of tamoxifen treatment in some patients. Owing to the vast differences between cell culture experiments and the human body, a more systematic in vivo investigation of clinical effects of tamoxifen over a range of different doses under various estradiol concentrations is warranted; (2) pioneering data on the efficacy of ‘Urenika’ extract against breast cancer in vitro; (3) a metastatic breast cancer animal model which successfully generated metastasis to distant sites (lymph nodes, lungs, livers and spleens), mimicking advanced stage of breast cancer in humans. This model could be used in future testing of the effect of PPE and the combined treatments (PPE with tamoxifen) on establishment and metastasis; and (4) a ‘refined’ non-invasive feeding methodology, which is more ethical than oral gavages, for tamoxifen administration in mice was developed and results obtained were comparable to the method of intraperitoneal injection. Using this model and the non-invasive feeding method, a dose-dependent stimulatory effect of tamoxifen on growth of 4T1 tumours was observed in mice. The current thesis has derived a new hypothesis which may be worth clinical investigation: tamoxifen may induce excessive leukocytosis which contributes to tumour invasiveness and growth. This thesis also represents a significant contribution to the potential use of potato extracts in reducing the risk of tamoxifen in stimulating cancer growth.
