The highest TEY, TPY, and TPC obtained were 57.83%, 12.80%, and 22.06%, respectively. The DSA ranged from 5.37 to 6.35 g g-1. The results indicated that extraction of phenolics from peel particles, produced by grinding to less than 0.6mm with a large cutting head, at a temperature of 20°C for 6 min using a solvent ratio of 4:1 could be the most economical and sustainable approach for industrial-scale production.To study the effects of drying, DPP was produced using HA drying and IR drying, and the peel compositions and phenolic extraction conditions were compared between DPP and WPP. The compositions of WPP and DPP on a dry basis are shown in Table 2.5 Composition of fresh and hot-air dried pomegranate peel. The WPP had higher contents of protein, ash, and crude fat than the DPP. The loss of these contents was reduced by avoiding the drying process. On the other hand, the HA DPP maintained higher total dietary fiber at 25.44%, and the ratio of insoluble dietary fiber to soluble dietary fiber was 8.84. This was higher than the values for WPP, which maintained 17.19% TDF and an IDF/SDF ratio of 4.93. Morais et al. compared the compositions of raw, freeze-dried, and oven-dried papaya peels. They reported similar findings for the differences in fiber content, stacking pots but the differences were not statistically significant. Observations consisted of the average subsampling results from the 30 aforementioned extraction conditions at different extraction times, temperatures, and solvent ratios.

Four vectors were estimated based on the eigenvectors of the correlation matrix of four variables: total extract yield , total phenolic yield , total phenolic content , and DPPH scavenging activity . The eigenvalues of F1 to F4 were 2.548, 0.899, 0.544, and 0.008, and the first three PCs accounted for 63.70%, 22.48%, and 13.61% of the sample variance, respectively, and represented 99.79% of the total variance in cumulation . Biplots of the observations and variables show the data distributions of F1-F2 and F1-F3. Confidence ellipses with 99% confidence intervals were used for each set of experiment groups, and no outliers were detected. PCA weighting scores of the four measured variables are listed in Table 2.6. Higher scores indicate a closer relationship between the variable and the factor. For instance, TEY and TPC were positively correlated with the F1 axis, whereas TPY and DSA were negatively correlated. In addition, TEY and TPY were positively correlated with the F2 axis, while DSA was negatively correlated with the F3 axis. Figure 2.7 also shows the data distribution for F1-F2 and F1-F3. For instance, the data point with a higher F1-axis value had higher TPC, which was extracted at 60°C for 6 min using a solvent ratio of 8:1. This was following the experimental results, indicating that PCA can be applied for future condition prediction.Extraction of bio-active compounds from waste fruit peel is an efficient approach to improve food system sustainability and industry profitability. This study developed a novel green process for antioxidant extraction from wet pomegranate peel and investigated the effects of extraction conditions on polyphenol yield and quality, including phenolic composition, DPPH scavenging activity, and color characteristics.

PCA condensed the multivariable analysis into three factors, which explained 99.79% of the variance and could be suitable for future process development. Three parameters, including drying preparation, extraction temperature, and solvent ratio, significantly influenced the extraction rate. Considering water usage and energy consumption, WPP extraction at 20°C for 6 min with a solvent ratio of 4:1 is recommended as an economic and sustainable process, resulting in 10.53% total phenolic yield with 88.93% punicalagin purity.Overweight is raising concern worldwide due to its high prevalence and various adverse health outcomes. According to a report from World Health Organization, an adult with Body Mass Index between 25.0 to 30.0 is defined as overweight, and over 1.9 billion adults worldwide were overweight in 2016, accounting for 39% of the population . Being overweight can further induce obesity when BMI increased beyond 30.0. These two statuses are major risk factors of physical and mental illness. Wilson et al. conducted 44-year follow-up research on 5209 participants aged 30 to 62 years from the Framingham cohort . Results showed that being overweight was related to elevated cardiovascular risks, including hypertension , angina pectoris , and coronary heart disease . Calle and Kaaks reviewed obesity and obese-related epidemiological studies. An increased risk of cancers was noted from 1.2-2 folds, including colorectal, endometrial, kidney, and oesophageal cancer . BeLue et al. studied the relation between mental healthiness and overweight in youth aged 12 to years in different races and ethnicity .

Their results revealed that overweight white and Hispanic youth possessed a higher percentage of self-reported depression, anxiety, and other mental and behavioral problems. Various causes contributed to being overweight. Among them, a calorie-dense and nutrient-poor diet is a major contributor along with a lack of exercise. Standard American Diet is a typical western diet that includes excess natural and added carbohydrates, fats, and sodium while lacking in consumption of fruits, vegetables, and whole grains . Improving the diet pattern for weight control is in need. Diet with the addition of phytochemicals, such as polyphenol, demonstrated positive health outcomes on weight management. Studies have suggested that polyphenol modulated the plasma and hepatic cholesterol in a few possible mechanisms, including inhibiting enzymes related to intestinal carbohydrate digestion and glucose absorption , inhibiting pancreatic lipase activity and fat absorption from the intestine , promoting β-oxidation of fatty acids , increasing bile excretion to eliminate the cholesterol , and regulating the gut microbiota towards a leaner composition . Pomegranate peel is a common underused fruit by-product from the juicing process and consists of up to 53.01% of the fruit weight . The high molecular weight polyphenols in the pomegranate peel are the major high-value phytochemicals and have been proven associated with reduced risks of chronic diseases , including type 2 diabetes and cardiovascular diseases . Among all the polyphenols in pomegranate peel, gallic acid , ellagic acid , punicic acid, and punicalagin-α, -β are responsible for most health benefits . It was worth noting that punicalagin is unique in pomegranate peel and demonstrated the greatest antioxidant activities with abundant hydroxyl groups, which can trap peroxyl radicals to reduce oxidation . Therefore, pomegranate peel is a promising source for polyphenols.By far, nearly all the studies of health benefits in pomegranate peel utilized liquid extractable polyphenol. Limited research focused on the pomegranate peel as a whole. Labib and Hossin characterized the effects of pomegranate peel powders and extracts on obese hypercholesterolemic rats solely from anthropometric and serum lipid. Insights of hepatic lipid profile were missing and the regulating mechanisms were not investigated in their study . Moreover, research has shown that the polyphenol and fiber in the food matrix might have a synergistic effect to promote health . Therefore, strawberry gutter system the objectives of this research were to compare the hypolipidemic properties of PPP and PPE and investigate the regulating mechanisms by supplementing the high-fat diets with different percentages of PPP and PPE to male Syrian hamsters.Pomegranate peel of Wonderful variety was collected from a juicing plant located in Buttonwillow, California in October of 2017. The peel was processed based on Wu et al. . In summary, the peel was sliced and ground into particles less than 0.6 mm. Then extract was obtained by mixing the peel particles with 4 times of water at 20 ⁰C for 6 mins, then filtered before administration to the hamsters. The male Syrian hamster was used since it possessed similarities of hepatic cholesterol and bile acid metabolism with humans compared to other rodents . The compositions of peel powder and extract were listed in Table 2.5.The study was approved by the Animal Care and Use Committee, Western Regional Research Center, USDA, Albany, CA, USA. 45 male golden hamsters were acclimatized for 2 weeks. They were fed with Purina Rodent Laboratory Chow and individually raised in a 20−22 °C environment with relative humidity at 60 %, and 12 h alternating light/dark cycle. After that, 45 hamsters were randomly divided into five groups for each diet as indicated in.

A high-fat diet with 20% fat energy intake was set as a control group. 5 and 10% of lyophilized PPP were supplemented into the HF diet ad libitum to evaluate the dose effects. In correspondence, 2.5 and 5% of lyophilized PPE addition were applied to investigate the effect of supplementation form. In this way, LP/LE group contained nearly 8.68 mg soluble phenolic compounds per kg body weight, and HP/HE group doubled the content. These dosages corresponded to approximately 70 mg and 140 mg per day in a 60 kg human according to the Km factor ratio of 5 and 37 for hamsters and humans , respectively . Table 3.1 summarized the diet composition. During 4 weeks of feeding, fresh food was provided to hamsters weekly. Their body weight and food intake were recorded weekly. Food efficacy, known as the weight gain per gram of diet consumption was calculated. At the end of the 4th week, hamsters were fasted for 14 h, anesthetized using isoflurane , and sacrificed based on the procedures in the previous study . 5 mL blood was drained by cardiac puncture into EDTA rinsed syringes, then centrifuged at 2000 g, 4 °C for 15 mins to collect plasma and stored at -80 ⁰C. The liver, kidney, and epididymal adipose were excised,weighed, and frozen in liquid nitrogen then stored at -80⁰C. Feces were collected during the last day of feeding and stored at -20 ⁰C.Plasma lipoproteins, including very-low-density lipoprotein -, low-density lipoprotein -, and high-density lipoprotein – cholesterol, were determined using size-exclusion chromatography as described . Specifically, A cholesterol reagent was delivered using Hewlett-Packard HPLC pump 79851-A at a flow rate of 0.2 mL/min. Lipoproteins were separated by injecting 15 μL of plasma onto the Superose 6HR HPLC column in Agilent 1100 HPLC chromatography system. Then the lipoproteins were eluted with a solution containing 0.15 M NaCl and 0.02% sodium azide at a flow rate of 0.5 mL/min. Base signals of the peak areas were calibrated by applying bovine cholesterol lipoprotein standards . Total cholesterols in plasma were counted as the sum of the VLDL-, LDL-, and HDL-cholesterol concentrations, interpolating from the standard curve. Plasma triglyceride was quantified using an enzyme colorimetric assay kit based on the absorbance at 505 nm . The liver and feces samples were ground in mortar and pestle, then the lipid was extracted with hexane/isopropanol at 60 °C using Dionex ASE 350 accelerated solvent extractor . The lipid extracts were evaporated to dryness at 37 °C under nitrogen. Total hepatic and fecal lipid contents were calculated based on the weighed extracted lipid over liver weight. Hepatic lipids were re-dissolved in hexane/isopropanol solvent and mixed with Triton X-100. After drying and diluting the mixture in DI water, total cholesterol and free cholesterol were determined with enzymatic kits , then esterified cholesterol was calculated based on the difference between TC and FC. Liver TG was measured using the same method for plasma TG.The body weight gains over 4-weeks of feeding were shown in Figure 3.1. All the diets elevated the total weight gain ranging from 18.14 to 33.82g, in order of HP, HF, HE, LP, and LE . The corresponding feed efficacy ratio was from 0.11 to 0.18 g/g. In both total weight gain and feed efficacy ratio, the HP diet was significantly lower while the LE diet was significantly higher compared to HF and HP diets . Possible reasons could be that the high fiber content in peel promoted earlier satiety , reduced the digestion and absorption of lipid content. At the same time, liquid extract in LE and HE diets tended to dissolve more reducing sugars from the pomegranate peel. Therefore, it promoted absorption efficiency and further weight gain. Sangüesa et al investigated the different adverse effects of glucose and fructose on the metabolism of female rats and observed that fructose had a greater impact on metabolic dysfunction . The carbohydrate composition of the extract and peel could be examined in the future for a better understanding of the mechanisms.As unusual LDL-elevating effects in plasma after PPP and PPE ingestion were observed, real-time qPCR was applied to investigate the potential mechanisms of diets modulating the lipid and cholesterol metabolism.