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    Isolation and characterization of a new potential source of bioactive peptides: White mulberry (Morus alba) fruits and its leaves
    (Elsevier Ltd, 2024) Kirac, Fatma Tuba; Şahingil, Didem; Hayaloğlu, Ali Adnan
    In this study, white mulberry (WM; Morus alba L.) and its leaf (WML) were hydrolyzed using enzymes at different preheating temperatures (50, 60, 70, 80, and 90 °C) with distilled water at a ratio of 1:10 (w/v). Pepsin, trypsin, chymotrypsin, and alcalase were employed for enzymatic hydrolysis, aiming to investigate the impact of heat treatment and enzymatic hydrolysis on bioactive properties; in particular, angiotensin-converting enzyme-inhibitory (ACE-i) and antioxidant activities. The highest hydrolysis efficiency was observed when using pepsin. The smaller peptides with <3 kDa had better ACE-i and antioxidant activities in both WM and WML samples. Regarding antioxidant activity, the highest level was identified at a preheating temperature of 90 °C in the WM sample, and at preheating temperatures of 50 °C and without heating in the WML samples. In conclusion, heat treatment and enzymatic hydrolysis were found to be a positive impact on ACE-i and antioxidant activities under various conditions. Moreover, the proteins derived from WM and WML were rich in the sources of potential ACE-i and antioxidant peptides. © 2023
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    PREVENTING OF MIGRATION IN FOOD CONTACT POLYVINYL CHLORIDE-BASED STRETCH FILMS WITH POLYLACTIC ACID LAYER
    (2024) Dagdelen, Adnan Fatıh; Kirac, Fatma Tuba; Saricaoglu, Furkan Turker
    In this study, the effectiveness of biodegradable polylactic acid (PLA) coatings for the prevention of residues migrating through polyvinyl chloride (PVC) films was investigated. PLA films prepared in chloroform at concentrations of 5, 10, 15 and 20 wt% were heat sealed to PVC film surfaces in a hot press (130 °C, 5 min, 5 tons). Physical, mechanical, FTIR and migration analyses were performed on these two-layer films. With PLA coating, the thickness of the films increased, mechanical properties decreased and some changes in color values occurred. It was determined by FTIR that there was no structural change on both surfaces of the films as a result of hot pressing. From the overall migration analysis, no migration was observed in the tests with aqueous food simulants, while migration was detected in fatty food simulants. In the specific migration analysis by GC-MS, di-2-ethylhexyl phthalate (DEHP) migration decreased by 50% with PLA coating. It is concluded that PLA coating of PVC stretch films may be a promising application to reduce migration.
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    Production and characterization of biodegradable bi-layer films from poly (lactic) acid and zein
    (Elsevier, 2023) Parlak, Mahmud Ekrem; Uzuner, Kubra; Kirac, Fatma Tuba; Ozdemir, Sebahat; Dundar, Ayse Neslihan; Sahin, Oya Irmak; Saricaoglu, Furkan Turker
    Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.
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    Recent advances in polylactic acid biopolymer films used in food packaging systems
    (Vup Food Research Inst, Bratislava, 2022) Kirac, Fatma Tuba; Dagdelen, Adnan Fatih; Saricaoglu, Furkan Turker
    The main purpose of food packaging is to maintain food quality and safety. For this purpose, packaging materials harmless to environment and health should prevent or reduce food spoilage. The packaging industry tends to natural and biodegradable materials due to migration of harmful components and causing environmental pollution of synthetic materials. The use of biodegradable materials as food packaging is one of the most studied approaches in recent years. Biodegradable polymers can be categorized in three groups as extracted from the biomass, produced by microorganisms and obtained from chemical synthesis. Polylactic acid (PLA) has unique properties as good transparency, availability in the market and low environmental impact, unlike fossil-derived materials. Compared to synthetic and other biodegradable polymers, PLA films have good tensile strength, as well as good barrier properties against flavour and smell. However, in order to solve disadvantages such as fragility and low thermal stability, plasticizers, stabilizers, fillers and antioxidants are used in the structure. In this review, it was aimed to present the latest advances in the functional properties of PLA important for its use in food packaging, namely, barrier, mechanical, thermal and optical properties, together with degradability.