Nutrition and Food Technology

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    (An-Najah National University, 2018-07-24) Dabous, Azza
    Background: Sourdough is a mixture of flour and water, which is fermented by the action of lactic acid bacteria (LAB) and yeasts. These microorganisms usually come from flour, dough ingredients or the environment. The selection and preservation of LAB suitable for industrial or artisanal bread making represents a useful tool to better address the biotechnology choices of the bakery industries. Thermal drying is one of the most popular methods used in the production of dried sourdough starters. However, drying may injury LAB in many ways. Material and methods: This study assessed the fermentation ability of 43 bacteria strains to be use as suitable sourdough starters, then the best fermentative strains were further classified and combined based on their biochemical and genotypic criteria. In the second phase of the study, we compared the drying effect of wet granulation and freeze drying method on the viability of starter culture. Results: Wet granulation was successful in obtaining better leavening height in comparing with fresh cells (p value < 0.05), while the leavening height obtained by using freeze dried sourdough starter was lower than the fresh cells. Wet granulation process has very little effect on the viability of microbial cells and doughs obtained were characterized by a considerable amount of lactic acid like the fresh cell starters. Sensory analyses univocally indicated that breads obtained by using the starter culture, above all as fresh cells, resemble those produced by means of the natural sourdough. Indeed, further efforts are required to point out a better strategy to stabilize the microbial combination during its shelf-life.
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    Effect of vacuum packaging combined with natural additives on the shelf life and quality traits of fresh thyme
    (Doaa Kanan, 2019-12-08) Kanan, Doaa
    Green thyme (Za’atar) is one of favorite herbs among Palestinian’s garden. It refers to genus Origanum of Lamiaceae family. This study aim to extend the shelf life fresh green thyme by hurdle technology by employing vacuum packaging technique combined natural additives (onion, sumac, lactic acid and oil and salt) then stored at room and refrigerated temperature to study the effect of natural additives combined with vacuum packaging on the physochemical properties of green thyme including color, taste, flavor, pH, chemical compositions and how they change during 42 days. Moreover, Study the probability of growth of Clostridium Botulinum in green thyme samples under anaerobic condition by using microbiological challenge test. Lactic acid was the most effective to keep different quality traits during storage. Refrigerated conditions were the best storage condition to extend the shelf life of thyme products. Green thyme leaves are very valuable agricultural product in Palestine. Until now, this product is not exploited to the export market due to short shelf life; the findings of this study may contribute to increase the potential of this product for export market.
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    Consumer Sensitivity and Freshness Evaluation of Bakery Products
    (An-Najah National University, 2019-07-25) Zidan, Souzan
    Focaccia is a typical bakery product in Italy, which is highly appreciated for its sensory characteristics and has its own market. Its quality deterioration during storage is caused chiefly by various deteriorative events which include the loss of crispness linked to high water activity, starch retrogradation and lipid oxidation. The loss of freshness in bakery products negatively affects consumer’s liking and the product’s quality. The freshness perception of a food during its shelf life depends on both the sensory properties of the food and the consumer’s ability to perceive a sensory deterioration. Consumers differ in their abilities to perceive tastes and textures, and these perception differences may lead to different preferences. Sensory methods can be used to understand individual sensitivity of consumers. The main purpose of this research is to evaluate consumer perception of focaccia samples stored at different times and to explore whether there is an association between consumer sensitivity and the perception of focaccia samples. Focaccia with two different toppings (tomato &olives (F1), and frozen onion with oregano (F2)) were considered in this research. All samples were stored for 7, 15, 30, and 60 days at 20ºC. Consumer sensitivity to taste, odor and texture were evaluated by using PROP status test, odor pens test, and hardness test, respectively. Weibull distribution was used to describe the rejection function. CATA method was used to determine sensory attributes of focaccia samples. Nighty-nine consumers participated in the consumer test. Consumers were asked to eat each sample of focaccia and to answer the question:" Would you normally consume/buy focaccia? Yes or No?". They were asked also to choose the most suitable attributes that can describe the samples and to evaluate their liking by using 10cm scale anchored from “the most unpleasant imaginable” to “the most pleasant imaginable”. From survival analysis, it was observed that the acceptance percentage for samples stored for 60 days was slightly higher for samples F2 (50%) compared to (47%) for samples F1. The shelf life was estimated as the storage time that corresponded to 50% consumers acceptance in 58 ±6 d, and 61±5 d, respectively for samples F1 and F2. For sample F1, CATA questions results showed that there are significant differences for both negative attributes (stale, dry tomato, hard, raw dough) and positive attributes (soft, typical focaccia flavor, sweet tomato, fresh tomato). In the same way, for sample F2, CATA questions results showed that there are significant differences in terms of both negative (stale, hard, onion taste) and positive (soft, pungent onion taste) attributes. For both types of samples, it was also noted that fresh samples were liked as the as those stored for 60 days. Our findings also showed that there is no significant association between liking scores of focaccia and socio-demographic variables (age and gender). We recommend that the current study should be followed up with larger number of consumers. Future studies should also assess participants’ psychological and personality traits.
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    (2021-07-26) Altamimi, Dr. Mohammad; De Filippis, Dr. Francesca
    Aim: The main aim of this study is to evaluate the possible influence of the adherence to the Mediterranean diet on gut microbiome composition during pregnancy. Design: Seventy-six healthy pregnant women participated in a parallel 9-months randomized controlled trial. Thirty-five participants were instructed to consume a diet inspired to Mediterranean dietary pattern (MedD), and 41 maintained their habitual diets (ConD). Dietary adherence and gut microbiome were monitored over the study period. Design and results: We retrieved dietary information and assessed gut microbiome by shotgun metagenomics in 76 pregnant women following Med and control diets. The majority of the women in MedD group increased the adherence to the MedD. We detected associations between the consumption of MedD and the abundance of beneficial microbes, such as some fiber-degrading bacteria and some taxa associated with the degradation of polyphenols, whose role in the human gut warrants further research. Conclusions: Switching subjects to a MedD (increasing their adherence to the MedD) during pregnancy can be considered as a promising strategy to improve their gut microbiome, possibly influencing the gut microbiome development in newborns.
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    The Effect of Different Dietary Patterns on Anthropometric Measurements Amongst Obese and overweight People Visiting different Dietetic Centres In West Bank: A Prospective Cohort Study
    (جامعة النجاح الوطنية, 2020-11-01) Suleiman, Yousef
    Background Overweight and obesity are major public health problems and the most common nutritional disorders. The prevalence of overweight and obesity is rising at an alarming level worldwide and Palestine shares world in this epidemic. The aim of this study is to evaluate the effect of different diet patterns practised by Palestinians on body weight, as well to evaluate effect of different variables on weight loss. Methodology A prospective cohort study was conducted on 1368 participants (19.86% males and 81.14%females), data were collected from Nutrition centres in West Bank. In nutrition centres they used BOCA X1 body composition analyser to calculate LBM. The nutrition analysis for prescribed diet programmes was done by ESHA software. Statistical analysis was done by SPSS version 25. The body mass index (BMI) weekly changes for each participant were taken over 12 consecutive visits. All participants must have Initial BMI between 25 and 60. The duration of 1 diet pattern was between 7 to 9 days. Females participants must not be pregnant or lactating. The effect of 5-isocaloric dietary patterns namely; low carbohydrate diet (LCD), low fat diet (LFD), vegetarian diet (VD), intermittent fasting diet (IFD) and Mediterranean diet (MD), in addition to, gender, initial BMI, lean body mass (LBM), total dietary carbohydrate intake (TDCI) an dietary fibre intake (DFI) on BMI were evaluated using General linear model. Different one-way ANOVAs were conducted to compare the effect of the 5-dietary patterns on BMI, the effect of different dietary patterns in different weeks and the difference between males and females. Results The results indicated a significant effect (p-value<0.05) of the seven variables on BMI lowering. Being Males have more effect on lowering BMI (0.34) than female. BMI lowering effect has increased by (0.0021) for each one gram increase in daily fibre intake. Increasing LBM led to increase in BMI lowering by (0.001). BMI lowering effect was inversely related with TDC (0.0005). Initial BMI has correlated positively with BMI lowering effect (0.0046). With regard to week numbers(visit order), the results have shown that all dietary patterns had high decrease in BMI in the first week of visits, however, such lowering effect on BMI has gradually declined from week 2 through week 12. The BMI lowering of the first week was 0.5791 more than the 12th week. With regard to the 5-dietary patterns effect on lowering BMI, results from ANOVA have shown that LCD has the highest lowering effect on BMI while VD has the lowest lowering effect on BMI. The other 3-diet patterns IFD, MD and LFD have no significant difference between them on their BMI-lowering effect.The mean BMI change for each of the five diets pattern was LCD (0.3310 ±0.3291), LFD (0.2756 ± 0.3003), IFD (0.2658 ± 0.2961), MD (0.2627 ± 0.3230) and VD (0.2233 ± 0.2546). Conclusion Weight loss is positively affected by initial BMI, LBM and TDF. Males lose more weight than females .TDCI had negative effect on losing weight. It was concluded that short term weekly effect of diet patterns was obvious for all 5-dietary patterns however, LCD was the best especially in the first weeks of weight management. MD and IFD, were practically more sustainable for long term effect. Therefore, LCD can be recommended for initial stages of weight management to show weight loss. Time factor is important for all diet patterns as the weight loss was more in the first weeks and declined gradually