Publications by authors named "Ioannis Giavasis"

Nowadays, the global animal industry faces considerable challenges in securing sufficient feed resources. Responding to consumer demands for reduced use of antibiotics in animal nutrition, better animal welfare status, and reduced impact on the environment, there is an increased urgency to develop innovative functional feeds with a reduced environmental footprint and the ability to improve meat quality and safety. In an effort to explore innovative feed ingredients for growing pig diets, the combined dietary supplementation of larvae and chitosan was investigated.

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New sustainable sources of feeds, which can enhance the health and welfare of farm animals, lower feeding costs, and lead to safer products, are of high priority in modern animal production systems. In the present study, a novel silage created from Greek olive, winery, and feta cheese waste by-products, was evaluated as a feed ingredient at different inclusion rates (0%, 5% or 10%) in 34-day-old weaned pigs. The potential beneficial effects on performance, health and intestinal digesta microflora balance of the pigs were evaluated.

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The purpose of this study was to evaluate the dietary use of novel silage that was created by combining three agro-industrial wastes produced in bulk, i.e., olive mill wastewater, grape pomace, and deproteinized feta cheese whey, in the diets of broiler chickens.

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The advances made by microbiome research call for new vocabulary and expansion of our thinking in microbiology. For example, the life-forms presenting in both unicellular and multicellular formats invite us to rethink microbial existence, organization, growth, pathogenicity, and therapeutics in the 21st century. A view of such populations as parts of single organisms with a loose, distributed multicellular organization, introduced here as a germ-ganism, rather than communities, might open up interesting prospects for diagnostics and therapeutics innovation.

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Several novel antimicrobials with different concentrations of olive, pomegranate, and orange fruit pulp extracts were produced from agricultural byproducts and, after lyophilization, their antimicrobial activity and potential synergistic effects were evaluated in vitro and in food samples against foodborne pathogenic and spoilage bacteria and fungi. The Minimum Inhibitory of the tested bacteria was 7.5% or 10%, while fungi were inhibited at a concentration of 10% or above.

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In the present study, pomegranate peels, avocado peels, and seed vacuum microwave extraction solid by-products were supplemented in corn silage in order to investigate the effects on meat quality and growth rate in broiler chicken. There were 50 broilers, divided in two groups, treated with experimental or usual feed for 43 days (group A: 25 broilers fed with avocado and pomegranate by-products and group B: 25 broilers fed with corn-silage used as control). The results showed that broiler chickens fed with a diet supplemented with a mixture of pomegranate avocado by-products (group A) showed significant differences in chicken leg meat quality, significantly improving the level of proteins and fatty acids content in breast and leg meat, respectively.

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The present study aimed to assess the antimicrobial properties of encapsulated lyophilized powdered extracts of pomegranate peels (PP), avocado peels (AP) and avocado seeds (AS) in vitro and in vivo. Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) methods, optical density measurement, and well diffusion assay were used to determine antimicrobial activity against food borne bacteria (Gram- ), (Gram+ ), and fungi () based on a mixture design model. Additionally, the most effective powder was studied in vivo in yogurt, cream cheese, and minced meat burger.

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Bee bread is the only fermented product of the beehive. It constitutes the main source of proteins, lipids, vitamins, and macro- and microelements in honeybee nutrition and it exerts antioxidant and antimicrobial properties, though research on these aspects has been limited so far. In this study 18 samples of Greek bee bread, two of which were monofloral, were collected during different seasons from diverse locations such as Crete and Mount Athos and were tested for their bioactivity.

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Pomegranate pomace (PP) is the solid waste produced in bulk by the pomegranate juice industry which is rich in polyphenols and flavonoids that can replace the hazardous chemical antioxidants/antimicrobials currently used in the agro-food and cosmetics sectors. In the present work, the vacuum microwave assisted extraction (VMAE) of natural antioxidants from raw pomegranate pomace was investigated and successfully optimized at an industrial scale. For the optimization of PP VMAE a novel, highly accurate response surface methodology (RSM) based on a comprehensive multi-point historical design was employed.

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Orange pomace (OP) is a solid waste produced in bulk as a byproduct of the orange juice industry and accounts for approximately 50% of the quantity of the fruits processed into juice. In numerous literature references there is information about diverse uses of orange pomace for the production of high-added-value products including production of natural antioxidant and antimicrobial extracts rich in polyphenols and flavonoids which can substitute the hazardous chemical antioxidants/antimicrobials used in agro-food and cosmetics sectors. In this work and for the first time, according to our knowledge, the eco-friendly aqueous vacuum microwave assisted extraction of orange pomace was investigated and optimized at real industrial scale in order to produce aqueous antioxidant/antimicrobial extracts.

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The global interest in the use of plant by-product extracts as functional ingredients is continuously rising due to environmental, financial and health benefits. The latest advances in extraction technology have led to the production of aqueous extracts with high bioactive properties, which do not require the use of organic solvents. The purpose of this study was to optimize the conditions applied for the extraction of pomegranate peels (PP) via a "green" industrial type of vacuum microwave-assisted aqueous extraction (VMAAE), by assessing the potential bioactivity of the extracts (in terms of phenolic content and antioxidant activity), using a response surface methodology.

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The aim of the present work was to investigate the potential prebiotic action of Goji berry powder on selected probiotic bacteria grown in a nutritive synthetic substrate and in simulated gastric and intestinal juices. Different probiotic strains of and were grown in these substrates with or without the addition of encapsulated goji berry extracts of different polysaccharide and polyphenol contents. The results proved that the addition of the extracts promoted the proliferation of probiotic strains and, in particular, increased the number of bacterial colonies of (Bb), (Bb), and by 2, 0.

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In this study, the content composition and antioxidant activity of goji berry fruits from two species ( and ) were assessed. The total carbohydrate and phenolic contents were evaluated using attenuated total reflection Fourier-transform infrared (ATR-FT-IR) spectroscopy, while the antioxidant activity of fruits was examined with two in vitro methods, which are based on the scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethyl-benzthiazoline-sulfonic acid) (ABTS•⁺) free radicals. The fatty-acid profile was determined using gas chromatography coupled with mass spectrometry (GC-MS).

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In the present study we investigated the effects of an olive polyphenol-enriched yogurt on yogurt microflora, as well as hematological, physiological and metabolic parameters, blood redox status and body composition. In a randomized double-blind, crossover design, 16 (6 men, 10 women) nonsmoking volunteers with non-declared pathology consumed either 400 g of olive fruit polyphenol-enriched yogurt with 50 mg of encapsulated olive polyphenols (experimental condition-EC) or 400 g of plain yogurt (control condition-CC) every day for two weeks. Physiological measurements and blood collection were performed before and after two weeks of each condition.

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Fungal bioactive polysaccharides deriving mainly from the Basidiomycetes family (and some from the Ascomycetes) and medicinal mushrooms have been well known and widely used in far Asia as part of traditional diet and medicine, and in the last decades have been the core of intense research for the understanding and the utilization of their medicinal properties in naturally produced pharmaceuticals. In fact, some of these biopolymers (mainly β-glucans or heteropolysaccharides) have already made their way to the market as antitumor, immunostimulating or prophylactic drugs. The fact that many of these biopolymers are produced by edible mushrooms makes them also very good candidates for the formulation of novel functional foods and nutraceuticals without any serious safety concerns, in order to make use of their immunomodulating, anticancer, antimicrobial, hypocholesterolemic, hypoglycemic and health-promoting properties.

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The application of Fourier Transform near infrared spectroscopy (FT-NIRS) to near real-time monitoring of polysaccharide and biomass concentration was investigated using a gellan-producing strain of Sphingomonas paucimobilis grown in a stirred tank reactor. Successful models for both biomass and gellan were constructed despite the physichochemical complexity of the viscous process fluid. Modelling of biomass proved more challenging than for gellan, partly because of the low range of biomass concentration but a model with a good correlation coefficient (0.

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