Theodoros Varzakas

Activity of flavonoids and β-carotene during the auto-oxidative deterioration of model food oil-in water emulsions

The antioxidant effects of flavonoids and β-carotene during the thermal auto-oxidation of food relevant oil-in-water emulsions were spectrophotometrically assessed by measuring the formation of primary oxidation products (conjugated dienes and lipid hydroperoxides). An oxidatively sensitive model emulsion was selected as substrate of this study in terms of processing and compositional factors. At a concentration of 1.5mmolkgr(-1), only quercetin among the tested compounds significantly reduced the oxidative deterioration of cottonseed oil-in-water emulsions. Structural characteristics (positioning of hydroxyl group) or partitioning behaviour between the emulsion phases may modulate the flavonoid activity. The high oxygen pressure conditions of the experimental system may explain the lack of any antioxidant activity for β-carotene. The antioxidant potential of quercetin increased with its concentration until a specific level. On the contrary, the antioxidant concentration within the same tested range (0.75-3mmolkgr(-1)) did not impact the activity of catechin and β-carotene. Mixtures of β-carotene with flavonoids did not exert a tendency for increasing the activity of each individual compound.

Portable Biosensing of Food Toxicants and Environmental Pollutants

Portable biosensing of food toxicants and environmental pollutants , Portable biosensing of food toxicants and environmental pollutants , کتابخانه دیجیتالی دانشگاه علوم پزشکی و خدمات درمانی شهید بهشتی

Sea Buckthorn (Hippophae Rhamnoides) Lipids and their Functionality on Health Aspects.

Hippophae rhamnoides, also named as Sea Buckthorn(SB) is a spiny bush with long and narrow leaves, and orange yellow berries. It is native to Europe and mainly to Asia. The leaves, fruits and the seeds of sea buckthorn contain many bioactive compounds. These compounds are various natural antioxidants such as ascorbic acid, tocopherols, carotenoids, flavonoids, whereas besides them all we can find macronutrients such as proteins, lipids (mainly unsaturated fatty acids and phytosterols), vitamins (especially vitamin C), minerals, small amounts of sugars and organic acids. The present review focuses on the functionality of SB lipids and refers to those studies that suggest the sea buckthorn could have various beneficial effects on cardiovascular health, insulin and glucose response, renal health, hepatic health, Gastric health, epidermis health, cancer, ophthalmologic health and oxidative stress and toxicity. keywords: Sea buckthorn, Hippophae rhamnoides L., Functionality, Fatty acids, Lipids.

Reviewing Classical and Molecular Techniques Regarding Profiling of Probiotic Character of Microorganisms

In recent years the roles of probiotics as functional ingredients in food has been highly adopted by the consumers and are under constant investigation by the scientific community. As a result, several probiotic-containing foods have been introduced in the market with an annual share of several billion dollars. Of particular interest in the probiotics research is the profiling of probiotic character of the microbes involving both in vitro and in vivo approaches. Initially traditional microbiological techniques were used; however they suffer by many limitations and therefore the development of new techniques, which are primarily based on the analysis of nucleic acids have been introduced. The scope of this review is to present current knowledge about the methodological approaches that are used to quantify and characterize the potential probiotic character of microorganisms. Moreover, it will focus on molecular and non-molecular tools and finally will report some new perspectives in the study of probiotics using ‘’omics’’ techniques.

Production of Low-Alcohol Fruit Beverages Through Fermentation of Pomegranate and Orange Juices with Kefir Grains

Fermentation of pomegranate juice as single or mixed substrate with orange juice, without addition of extra nutrients, using kefir grains is proposed. Sugar consumption and ethanol production were monitored during fermentation, while the formation of lactic acid and the survival of lactic acid bacteria were determined during storage at 4 oC for 4 weeks. The results showed that addition of orange juice improved the ability of kefir grains to ferment pomegranate juice, and increased the survival rates of lactic acid bacteria (LAB) contained in kefir grains during storage. Specifically, 75% cells survived (6.48 log cfu/ml) after 4 weeks of storage in the fermented mixed substrate (24% in plain pomegranate juice). Lactic acid formation was observed in all products, especially in the mixed substrate (1.3-1.9 g/l), indicating metabolic activity during storage. In all cases a low decrease of pH was observed. The results show the possibility to produce low-alcoholic nutritious fruit beverages with potential antioxidant (due to pomegranate constituents) and probiotic properties (due to the probiotic species present in kefir grains). In addition sensorial tests that were conducted showed the consumers acceptance for all the fermented juices.

Glycemic Index of Two Different Fried Potato Varieties Cultivated Under Organic Fertilization Conditions

This study identified the glycemic index (GI) of two different commercially available varieties of potatoes, Lady Rosetta (LR) and Spunta (S), cultivated under organic fertilization conditions and fried in extra virgin olive oil. Eight healthy males 26 ± 1.5 years of age, 84.7 ± 3.2 Kg body mass and 19.2 ± 1.5% of body fat participated (mean ± SE). Volunteers consumed in a random order 50 g of anhydrous glucose in 300 ml of water (G), or 50 g of available carbohydrate of sliced and fried LR or S twice. Blood glucose was measured enzymatically from capillary blood samples before food consumption and at 15, 30, 45, 60, 90 and 120 min postprandially. Each meal was prepared and consumed in the morning after a 12-hour overnight fast, whereas diet and physical activity were controlled. For the calculation of GI the mean blood glucose values of the two trials (i.e. 1st and 2nd time) in each potato variety (i.e. LR or S) were considered. The incremental area under the blood glucose-time curve (IAUC) was used according to trapezoidal rule for the determination of GI. The IAUC was 5504 ± 1173 mg.min/dl and 4012 ± 911 mg.min/dl whereas the GI was 114 ± 15 and 83 ± 12 in LR and S respectively. However, these differences were not significant (IAUC: p= 0.21 and GI: p=0.20). Fried potato slices in extra virgin olive oil derived from LR and S potato varieties cultivated under organic fertilization conditions possess similar GI in healthy male volunteers. key words: glycemic Index, French Fries, Biological, Fertilization.

Lipid Profile and Antioxidant Properties of Selected Pear Cactus (Opuntia Ficus- Indica) Ecotypes From Southern Greece

The lipid profile was determined in selected ecotypes of Cactus pear (Opuntia ficus indica), and this research focused on the antioxidant properties of seeds from Cactus pear fruits. Using the methodology of methyl esters the composition of fatty acids of seeds was determined and in the case of antioxidant properties the known technique of Trolox Equivalent Antioxidant Capacity (TEAC) was used. The trolox evaluation assay was applied in aqueous organic extracts and their residues. The seed oil composition of cactus pear fruits was studied at harvest time. Linoleic acid (70.03%) was the dominant fatty acid, followed by oleic acid (20.11%) and palmitic acid (11.86%), respectively. Among cactus pear seeds, polyphenols contribution to antioxidant properties ranged from 37.9% to 42% for TEAC values. According to the results, the seeds of Cactus pear are a good source of useful lipids and antioxidants. keywords: Opuntia spp., Cactus Pear, Phenolics, lipids Profile.

Carotenoids: From Plants to Food and Feed Industries

In this review, carotenoids from plants are described, and their natural existence is addressed. Carotenoids are 40-carbon isoprenoid molecules that produce the red, yellow, and orange pigmentation found in nature. Various plants, microalgae, bacteria, and fungi are natural sources of carotenoids and are presented in detail. The chemistry of carotenoids and their classification is also described along with the effect of carotenoids on human health which is explained with focus on lutein-zeaxanthin, astaxanthin, canthaxanthin, capsanthin, and lycopene. Clinical studies suggest that carotenoid consumption is associated with lower risk of cardiovascular disease, cancer, and eye disease. Finally, another issue discussed is the role of carotenoids in animals and their feed with focus on birds, fish and crustaceans, livestock, and poultry.

Minimally Processed Fresh Green Beverage Industry (Smoothies, Shakes, Frappes, Pop Ups)

The modernization and urbanization occurred during the last century were coupled with modifications in lifestyle and dietary habits. At the same time, industrial developments made it easier to meet the requirements for processed foods. Nevertheless, consumers are now interested in minimally processed foods owing to increase in their consciousness to have fruits and vegetables with superior quality and natural integrity with no additives. Processing in foods causes biochemical changes, high respiration rate, and high ethylene production. These factors contribute to discoloration, loss of firmness, development of off-flavors, acidification, and microbial spoilage. At the same time, food processors are using emerging approaches to process perishable commodities, along with enhanced nutritional and sensorial quality. The present review article is an effort to classify the minimally processed fruits, vegetables, and juices and simultaneously give us details about the manufacturing beverages (juices, smoothies, shakes, etc.).

Survival of Listeria Monocytogenes in Tomato Juice at 5 and 30°C Storage

Listeria monocytogenes is a food-borne pathogen and has been associated with a variety of food products including fruits and vegetables, which are important for a healthy human diet. L. monocytogenes survives and grows at low temperatures and thus it can be multiplied to dangerous levels in a product which is kept at refrigeration temperatures. This work examines the ability of L. monocytogenes to survive, in a product of high consumption frequency, such as tomato juice, in correlation to storage temperature. The results indicate that a significant number of cells survived in tomato juice whether the storage temperature was 30°C or 5°C, although the refrigerator temperature slightly reduces the survival of L. monocytogenes cells. An understanding of the cold stress response of the pathogen will be helpful in the design of effective methods to control L. monocytogenes in freezing foods in order to provide consumers with a safe product. keywords: Listeria monocytogenes; tomato juice; refrigeration; vegetables; food safety