Amani S. Al-Rawahi

Pomegranate (Punica granatum) Peel Extract Efficacy as a Dietary Antioxidant against Azoxymethane-Induced Colon Cancer in Rat

Functional foods include antioxidant nutrients which may protect against many human chronic diseases by combating reactive oxygen species (ROS) generation. The purpose of the present study was to investigate the protective effect of pomegranate peel extract (PPE) on azoxymethane (AOM)-induced colon tumors in rats as an in vivo experimental model. Forty Sprague-Dawley rats (4 weeks old) were randomly divided into 4 groups containing 10 rats per group, and were treated with either AOM, PPE, or PPE plus AOM or injected with 0.9% physiological saline solution as a control. At 8 weeks of age, the rats in the AOM and PPE plus AOM groups were injected with 15 mg AOM/kg body weight, once a week for two weeks. After the last AOM injection, the rats were continuously fed ad-libitum their specific diets for another 6 weeks. At the end of the experiment (i.e. at the age of 4 months), all rats were killed and the colon tissues were examined microscopically for lesions suspected of being preneoplastic lesions or tumors as well as for biochemical measurement of oxidative stress indices. The results revealed a lower incidence of aberrant crypt foci in the PPE plus AOM administered group as compared to the AOM group. In addition, PPE blocked the AOM-induced impairment of biochemical indicators of oxidative stress in the examined colonic tissue homogenates. The results suggest that PPE can partially inhibit the development of colonic premalignant lesions in an AOM-induced colorectal carcinogenesis model, by abrogating oxidative stress and improving the redox status of colonic cells.

Phenolic constituents of pomegranate peels (Punica granatum L.) cultivated in Oman.

Aims: This study was undertaken to analyze total phenolics and total flavonoids contents; and total antioxidant capacity of pomegranate peel extract and to identify the major functional components in the extract. Study Design: The extract was subjected to ESI-MS/MS. Place and Duration of Study: Department of Food Science and Nutrition, Sultan Qaboos University and DARIS Research Center, University of Nizwa, between December 2011 and August 2012. Methodology: Pomegranate peel extract was analyzed using a Waters Quattro Premier XE tandem quadrupole mass spectrometer (Waters Corporation, Manchester, UK) Original Research Article European Journal of Medicinal Plants, 4(3): 315-331, 2014 316 equipped with electro-spray ionization (ESI) source. Instrument control and data acquisition were performed using Mass Lynx ver. 4.1 software. The instrument was calibrated for nominal resolution for MS1 and MS2 up to 1200 m/z using the sodium caesium iodide standard calibration solution. Results: Results revealed high contents of total phenolics (64.2 mg Gallic acid equivalent/ g dry solids) and total flavonoids (1.4 mg Catechin equivalent/ g dry solids) respectively. Total antioxidant capacity ranged from 42.3 – 461.2 μmolTrolox equivalent/ g dry solids. The analysis revealed the presence of 61 different polyphenols in the extract among which 12 hydroxycinnamic acids, 14 hydrolysable tannins, 9 hydroxybenzoic acids, 5 hydroxybutanedioic acids, 11 hydroxy-cyclohexanecarboxylic acids and 8 hydroxyphenyls. Major compounds were tannins and flavonoids such as; illogic acid, gallic acids, punicalin, and punicalagin. Conclusion: A wide variety of phytochemicals present in pomegranate peel extract were identified. These functional compounds in pomegranate peels could be utilized by the food industry and pharma/nutraceutical’s industry. Further work should be done to isolate and quantify major functional compounds of pomegranate peels such as ellagic acid.

Chemical Composition, Water Sorption Isotherm, and Phenolic Contents in Fresh and Dried Pomegranate Peels

Pomegranate peels were dried by freeze drying at 20°C; air and vacuum drying at 40, 60, and 90°C; and sun drying. The moisture sorption isotherm was measured and modeled using the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–De Boer (GAB) models. Two solvents (methanol and ethanol) and water were used to extract the phenolic compounds in pomegranate fruit peel. Fresh peels contained 5,990, 4,530, and 8,460 mg gallic acid equivalent (GAE)/100 g dry-peel solids for methanol, ethanol, and water extracts, respectively. The total phenolic content of ethanol extracts of freeze-dried peels was comparable to that of fresh peels (4,900 mg GAE/100 g dry-peel solids), whereas air- and vacuum-dried peels had significantly lower phenolic contents. Peels air dried at 60°C had the highest phenolic content (2,320–4,650 mg/100 g dry-peel solids) compared to samples air dried at 40 or 90°C (1,160–4,480 mg/100 g dry-peel solids), whereas vacuum-dried peels did not show any trends with temperature. In general, methanol had a higher capacity for extracting phenolic compounds from dried pomegranate peels than water, and ethanol showed a low extraction capacity. In all cases, phenolic compounds were significantly lower in ethanol extracts compared to methanol or water extracts (p < 0.05). In addition, phenolic compounds soluble in water and ethanol were more sensitive to all drying methods except freeze drying.

Development of a Date Confectionery: Part 1. Relating Formulation to Instrumental Texture

The Sultanate of Oman in the Middle East produces a large amount of dates, which in 2003 amounted to about 285,360 tons. Most of the harvest is used for animal feed and the rest for local consumption. The need to utilize dates in a more efficient way is a must. In this study, a new candy was developed using two date varieties, i.e., Khalas and Umesilla thus spanning from top to bottom of the quality range in terms of consumer preference. Proximate analysis argues that products are nutritious and can contribute especially to the daily allowance in macro-elements. Texture profile analysis suggests that the affordable date candy of Umesilla belongs to the same family of products with the Khalas candy in terms of the attributes of hardness, firmness, brittleness and adhesiveness. Products were aged up to thirteen weeks, with results demonstrating that the textural quality remains stable throughout the storage period.

Development of a date confectionery: Part 2. Relating instrumental texture to sensory evaluation

Successful commercialization of a date confectionery requires development on a sound technological basis. In Part I of this series, a relationship was established between the ingredients of a formulation, and the instrumental texture of the final product. In the present communication, we go a step further by developing a correlation between textural attributes, and the corresponding sensory parameters, as judged by trained panelists. In doing so, confections were made using table and processing dates and subjected to a “two-bite” texture profile analysis, thus recording a series of useful attributes. Taste panelists were trained to identify the corresponding sensory parameters thus constructing a scoring card as part of a quantitative descriptive analysis. Results demonstrated that instrumental texture can be “handshaken” to sensory evaluation to provide an avenue of developing and controlling the quality of a date confectionery made with affordable raw materials.

Glass transition of pomegranate skin, as analyzed by thermal, mechanical, and nuclear magnetic resonance methods

ABSTRACT Glass transition of pomegranate skin was measured by thermal, mechanical, and magnetic resonance techniques. Differential scanning calorimetry thermogram showed a shift (i.e., onset glass transition at 20°C) followed by an endothermic peak (i.e., solids-melting peak at 165°C and enthalpy 140 kJ/kg). Overlapping of the glass transition and melting was observed in the differential scanning calorimetry thermogram; however, more sensitive modulated differential scanning calorimetry allowed to separate two transitions (i.e., glass transition from reversible and melting from non-reversible thermograms). The onset of mechanical glass-rubber transition from differential mechanical thermal analysis was observed at 122°C with a shift in the storage modulus (E′); however, the onset of liquid-like or entangled-reaction dominating transition was observed at 70°C (i.e., onset peak in loss modulus, E′′) and peak at 184°C. In addition onset peak in tan δ was observed at 113°C and peak at 201°C. Spin–spin (T2 relaxation) and spin-lattice (T1 relaxation) relaxations in time domain nuclear magnetic resonance was modeled by two-exponential relaxation curve (i.e., rigid and flexible domains). T2 relaxation showed maximum peak with an onset at 40°C with maximum peak at 150°C. Rigid domain of T1 relaxation showed a minimum peak onset at 40°C and a minimum peak at 120°C, whereas flexible component showed an onset at 20°C and a minimum peak at 160°C.