Influence of Climate, Variety and Production Process on Tocopherols, Plastochromanol-8 and Pigments in Flaxseed Oil

Marko Obranović1*, Dubravka Škevin1, Klara Kraljić1, Milan Pospišil2Sandra Neđeral1, Monika Blekić1 and Predrag Putnik1*

1Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia
2Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, HR-10000 Zagreb, Croatia

Article history:
Received May 12, 2015
Accepted June 2, 2015

Key words
flaxseed oil, variety, cold pressing, conditioning, tocopherols, plastochromanol-8, carotenoids, chlorophyll, climate

The objective of this study is to compare the influence of genotype, environmental conditions and processing methods after maturation and harvesting of four varieties of flaxseed (Altess, Biltstar, Niagara and Oliwin) on the levels of tocochromanols, carotenoids and chlorophyll in flaxseed oil. Samples were produced by cold pressing of dry seeds and seeds heated for 30 min at 60 °C. Temperature, sunshine and rainfall were primary environmental conditions included. Grand mean of mass fraction of γ-tocopherol was (522±29), of plastochromanol-8 (305±2) and total tocochromanols (831±3) mg per kg of oil. The highest levels of these compounds and strongest antioxidant activity were found in cold-pressed oil of Biltstar variety. During seed maturation, levels of γ-tocopherol and plastochromanol-8 increased with average temperature and total sunshine and decreased with total rainfall. Fifth week after flowering was identified as the maturation period with best climate conditions to achieve optimal tocochromanol content. Grand mean of mass fraction of carotenoids expressed as β-carotene was (1.83±0.01) and of chlorophyll expressed as pheophytin a (0.43±0.10) mg per kg of oil. Altess variety had the highest levels of pigments. Antioxidant activity decreased with the increase of chlorophyll, while correlations with carotenoids were not determined. Generally, oil obtained by cold pressing had higher levels of tocochromanols and lower levels of pigments but similar antioxidant activity to the oil after seed conditioning. The results of this study contribute to identifying the flaxseed variety that is the best for oil production with the highest antioxidant activity and nutritive value, and provide better understanding of tocochromanol biosynthesis depending on different climate conditions.

*Corresponding authors:   email3 (oil chemistry)
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   email3 (statistics)
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Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries

Aryou Emamifar1* and Mehri Mohammadizadeh2

1Department of Food Science and Technology, University of Kurdistan, 66177-15177 Pasdaran Street,
 Sanandaj, Kurdistan, Iran
2Department of Food Science and Technology, Science and Research Branch, Islamic Azad University of
  Kurdistan, 6616935391, Feiz Abad, Sanandaj, Kurdistan, Iran

Article history:
Received July 15, 2014
Accepted May 22, 2015

Key words
strawberry, ZnO nanoparticles, nanocomposite, antimicrobial packaging

Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated aft er 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5 %, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68 %) were observed in packages containing 3 % of ZnO nanoparticles with 10 % polyethylene-grafted maleic anhydride.

*Corresponding author:   email3   
                                               tel3  +98 873 366 4600
                                               fax2  +98 873 366 4601



Antioxidant and Antimicrobial Effects of Pistacia lentiscus L. Extracts in Pork Sausages

George Botsaris, Antia Orphanides, Evgenia Yiannakou, Vassilis Gekas and Vlasios Goulas*

Cyprus University of Technology, Department of Agricultural Sciences, Biotechnology and Food Science, CY-3603 Lemesos, Cyprus

Article history:
Received January 7, 2015
Accepted July 2, 2015

Key words
lipid oxidation, mastic tree, natural antioxidants, phenolic compounds, plant extracts, 
total viable count

Pistacia lentiscus fruits are ingredients of traditional Cypriot sausages. The objective of this study is to evaluate P. lentiscus extracts as natural additives to the sausages. First, the phenolic content and antioxidant activity of fruit and leaf extracts were determined. Results revealed that leaves are richer source of polyphenolic antioxidants than fruits, with methanol being the better extraction solvent. In the next step, the antioxidant and antimicrobial effects of methanolic extracts (300 mg/kg) in the pork sausage formulation were investigated. Peroxide, acid and thiobarbituric acid-reactive substance values demonstrated that both fruit and leaf extracts reduced the rate of lipid oxidation of sausages at 4 °C. Total viable count revealed significant differences on the fifth day of storage, with better microbial inhibition by leaf extract. No significant differences between the extracts were observed after the tenth day of storage. Overall, the extracts can be used to prevent lipid oxidation and reduce microbial spoilage during the first days of storage of fresh traditional pork sausages.

*Corresponding author:   email3                                                                   
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Comparison of Enzymatic and Ultrasonic Extraction of Albumin from Defatted Pumpkin (Cucurbita pepo) Seed Powder

Gia Loi Tu, Thi Hoang Nga Bui, Thi Thu Tra Tran, Nu Minh Nguyet Ton and Van Viet Man Le*

Department of Food Technology, Ho Chi Minh City University of Technology 268 Ly Thuong Kiet Street, District 10, 70 000 Ho Chi Minh City, Vietnam

Article history:
Received March 7, 2015
Accepted July 2, 2015

Key words
albumin, Cucurbita pepo, extraction, functional properties, hydrolase, ultrasound

In this study, ultrasound- and enzyme-assisted extractions of albumin (water-soluble protein group) from defatted pumpkin (Cucurbita pepo) seed powder were compared. Both advanced extraction techniques strongly increased the albumin yield in comparison with 
conventional extraction. The extraction rate was two times faster in the ultrasonic extraction than in the enzymatic extraction. However, the maximum albumin yield was 16 % higher when using enzymatic extraction. Functional properties of the pumpkin seed albumin concentrates obtained using the enzymatic, ultrasonic and conventional methods were then evaluated. Use of hydrolase for degradation of cell wall of the plant material did not change the functional properties of the albumin concentrate in comparison with the conventional extraction. The ultrasonic extraction enhanced water-holding, oil-holding and emulsifying capacities of the pumpkin seed albumin concentrate, but slightly reduced the foaming capacity, and emulsion and foam stability.

*Corresponding author:   email3  
                                               tel3  +84 8 3864 6251
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Characterisation of Sorbus domestica L. Bark, Fruits and Seeds: Nutrient Composition and Antioxidant Activity

Boris Majić1,2, Ivana Šola1*, Saša Likić1, Iva Juranović Cindrić2 and Gordana Rusak1

1Department of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
2Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 
HR-10000 Zagreb, Croatia

Article history:
Received November 19, 2014
Accepted June 12, 2015

Key words
service tree, food analysis, macroelements, microelements, phenolics, flavonoids, 
tannins, antioxidant activity

The aim of this work is to assess the nutritional value of service tree (Sorbus domestica L.) bark, fruit exocarp and mesocarp, and seeds by establishing the levels of macro- and microelements, total phenolics, flavonoids and tannins. Our results revealed that all of the tested service tree samples were rich in potassium. Bark was the best source of calcium and zinc, while seeds were the best source of magnesium. Compared to the bark and seeds, fruit exocarp and mesocarp contained signifi cantly lower amounts of these three elements. Immature exocarp and bark contained the highest amounts of total phenolics and showed the highest antioxidant activity. Maturation significantly decreased the amount of total phenolics in fruits, as well as the antioxidant activity of total phenolics and total tannins from exocarp, but not from mesocarp. Exocarp was the richest in total flavonoids. Based on the obtained data, we have concluded that the under-utilised species S. domestica L. could serve as an important source of mineral elements and antioxidants in the human diet.

*Corresponding author:  email3 
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