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  • Kirje
    The effect of plant origin ingredients on the quality characteristics and chemical profile of meat products : doctoral dissertation : natural sciences, chemistry (N 003)
    (Kaunas University of Technology, 2024) Kerner, Kristi; Rimantas, Petras; Jõudu, Ivi; Kaunas University of Technology
    This doctoral dissertation was prepared at Kaunas University of Technology, Faculty of Chemical Technology, Department of Food Science and Technology and at Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Chair of Food Science and Technology during the period of 2018–2023. The studies were financed by the European Union’s Horizon 2020 research and innovation programme project ERA Chair for Food (By-) Products Valorisation Technologies of Estonian University of Life Sciences – VALORTECH (grant agreement No. 810630).
  • Kirje
    The potential and limitations for applications of oat proteins in the food industry
    (Estonian University of Life Sciences, 2022) Ibrahim, M.; Aav, Alice; Jõudu, Ivi
    Oat proteins have gained high attractive popularity in the market as future protein alternatives in various food products. The extracted oat protein fractions are characterised by a relatively high protein content and a unique amino acid profile compared to other cereal grains. From another aspect, the oat protein is separated unintentionally during the production of oat flours, oat drinks, and oat flakes which encourages the incorporation of oat proteins in the food industry to valorise the food wastes. Therefore, commercial oat proteins possess poor technofunctionality and water solubility in the usual environmental conditions for most food products; therefore, modification of oat proteins functionalities is highly recommended. Several modification methods, including chemical, physical and enzymatic, have been proposed to improve the techno-functionality of native oat proteins and their biological activities. This review highlights the nutritional value of the oat protein fractions, their techno-functional properties and their food industrial challenging limitations. Additionally, it summarises several prospective methods effective for boosting the functionality of oat protein fractions and broadening their application in a range of food industries (bakery, dairy, meat, and their alternative products) with an overview of their impact on humans, animals, and environmental health.
  • Kirje
    Amperometric method for the determination of cellulase activity and its optimization using response surface method
    (SpringerOpen, 2022) Nero, Georg; Kivirand, Kairi; Othman, Sana Ben; Rinken, Toonika
    Cellulases are a group of enzymes, which catalyse different steps of cellulose hydrolysis, and are broadly used in industry as unpurified mixtures of several enzymes. The total activity of cellulase is defined as the ability of the enzyme to produce glucose, which is the final product of cellulose hydrolysis, and is expressed in cellulase units. However, common strategies for the determination of the cellulolytic activity of industrial cellulase preparations are based on the assessment of different steps of cellulose hydrolysis, and the results obtained with different methods are not similar. The aim of the present study was to develop an assay for the determination of cellulase activity that relies on the amperometric determination of the final product of cellulose hydrolysis glucose. The assay conditions were optimized using response surface methodology (RSM) combined with Box-Behnken design. The detection limit of the proposed method was 1.71 ± 0.06 U. We compared the results of the amperometric method with the ones obtained with the spectrophotometric method and viscosimetry in a commercial cellulose preparation.
  • Kirje
    Bovine colostrum: Postpartum changes in fat globule size distribution and fatty acid profile
    (Elsevier, 2022) Sats, Andres; Yurchenko, Sergei; Kaart, Tanel; Tatar, Vilma; Lutter, Liis; Jõudu, Ivi
    Although “zero waste” valorization concepts are gaining increasing attention, colostrum, a byproduct of milk production, remains underused due to technological challenges. Information about the fat fraction and the size of fat globules is needed to address these challenges, but such information is currently lacking. This study aimed to fill this gap in the knowledge by measuring the size distribution of bovine colostrum fat globules (CFG) and analyzing its relationships with postpartum milkings, parity, and fatty acids (FA) profile. Four sequential postpartum colostrum samples were collected from 44 cows and analyzed for the abovementioned parameters. The results indicated that CFG size increases almost twice during postpartum milkings (from ~5 to ~10 μm), whereas lactation has little, if any, effect on CFG size. The FA profile analyses showed that the content of most FA in the fourth postpartum milking was different from the previous milkings. The correlation analyses between CFG size and FA profile also demonstrated that the fourth milking was clearly distinguishable from the first 3 postpartum milkings. For example, the saturated FA content from the first 3 milkings had a positive correlation with smaller CFG (and a negative correlation with larger CFG), whereas the fourth milking demonstrated no correlations. Based on these CFG size and FA profile analyses, the results of this study suggest that the first 3 postpartum milkings can be considered as colostrum, whereas the fourth milking represents transition milk. Information about CFG size distribution enables modification of the FA profile of colostrum products and the ability to create better valorization technologies for colostrum-based food and feed supplements.
  • Kirje
    Extraction of lipophilic components from rowanberry pomace with supercritical CO2 and their fractionation at subcritical conditions at low temperatures
    (Research Square, 2023) Sarv, Viive; Venskutonis, Petras Rimantas; Jūrienė, Laura; Baranauskienė, Renata; Urbonavičienė, Dalia; Viškelis, Pranas; Bhat, Rajeev
    Rowanberry pomace lipids were extracted with supercritical CO2 (42.4 MPa, 53 °C) using 0-7% of a co-solvent ethanol and fractionated by reducing 1st separator’s (S1) pressure to 7 MPa and cooling to 0, -10 and -20 °C for precipitating ‘heavier’ fraction (HF). The second separator (S2) was depressurized at ambient temperature for collecting ‘lighter’ fraction (LF). The yield of LF increased by decreasing S1 temperature and increasing the amount of a co-solvent. The concentration of β-carotene increased in LF by decreasing S1 temperature and increasing co-solvent concentration; at -20 °C it was by 66.7% higher than in the non-fractionated extract. The concentrations of tocopherols and phytosterols were also remarkably higher in LF. In total, 62 compounds were identified in the headspace volatile fraction of LF, benzaldehyde and benzyl alcohol being the most abundant constituents. In conclusion, fractionation enabled obtaining the fractions with the higher concentration of selected lipophilic rowanberry constituents.
  • Kirje
    Sustainable Management and Valorization of Agri-Food IndustrialWastes and By-Products as Animal Feed: For Ruminants, Non-Ruminants and as Poultry Feed
    (MDPI, 2023) Malenica, Dunja; Kass, Marko; Bhat, Rajeev
    Substantial increase in the production of agri-food commodities over the past years has resulted in the generation of enormous volumes of wastes and by-products, thus contributing to increased environmental pollution. Being an under-exploited raw material which are rich in bioactive compounds (e.g., polyphenols, dietary fibre, oils, essential vitamins, minerals, etc), novel strategies and initiatives have been proposed and implemented for the effective management and valorization of these wastes and by-products. The proposed initiatives and strategies support the concepts of EU circular economy and green biorefinery, thus promoting sustainability. One of the strategies of management of waste and by-products includes the effectual development of nutritious low-cost sustainable animal feed. Currently, in the world market, there are a range of fruit and vegetable wastes and by-products that have been effectively introduced in animal diets. Within this context, this systematic review focuses on a diversified group of agri-food wastes (and the industrial by-products), their bioactive components, the opportunities for the development of animal feed or feed supplements (for Ruminants, Non-Ruminants and as Poultry feed) and conclusively the health benefits imparted. In addition, the safety issues and regulations aspects are also covered.
  • Kirje
    Extraction of lipophilic components from rowanberry (Sorbus aucuparia L.) pomace with supercritical CO2 and their fractionation at subcritical conditions at low temperatures
    (SSRN, 2024) Sarv, Viive; Venskutonis, Petras Rimantas; Tamkutė, Laura; Baranauskienė, Renata; Urbonavičienė, Dalia; Viškelis, Pranas; Bhat, Rajeev
    Rowanberry pomace lipids were extracted with supercritical CO2 (42.4 MPa, 53 °C) using 3-7% of a co-solvent ethanol and fractionated by reducing 1st separator’s (S1) pressure to 7 MPa and cooling to 0, -10 and -20 °C for precipitating ‘heavier’ fraction (HF). The second separator (S2) was depressurized at ambient temperature for collecting ‘lighter’ fraction (LF). The yield of LF increased by decreasing S1 temperature and increasing the amount of a co-solvent. The concentration of β-carotene increased in LF by decreasing S1 temperature and increasing co-solvent concentration; at -20 °C it was by 66.7% higher than in the non-fractionated extract. The concentrations of tocopherols and phytosterols were also remarkably higher in LF. In total, 62 compounds were identified in the headspace volatile fraction of LF, benzaldehyde and benzyl alcohol being the most abundant constituents. In conclusion, fractionation enabled obtaining the fractions with the higher concentration of selected lipophilic rowanberry constituents.
  • Kirje
    Bovine colostrum casein: Post-partum dynamics of micelle size, content, and associated traits
    (Elsevier, 2024) Sats, Andres; Kaart, Tanel; Jõudu, Ivi
    In milk, casein exists in the form of colloidal casein micelles (CM), which are crucial for various biological functions such as neonatal nutrition, calcium phosphate control, and amyloid fibril suppression. However, bovine colostrum casein has received less attention despite its importance. The objective of this study was to investigate the size of colostrum CM and their relationship with compositional traits during four post-partum milkings. A total of 184 samples (collected at 12 ± 1 h intervals) were obtained from 46 cows over four sequential milkings. The results demonstrated a significant decrease in CM size of colostrum from 227.2 nm to 201.9 nm over the four post-partum milkings. Fat, protein, casein content, and Brix values also declined across milkings and showed a positive correlation with CM size, although the relationships were nonlinear. Understanding CM size can be valuable for decision-making regarding colostrum and transition milk processing due to its significant role.
  • Kirje
    Meat extenders from different sources as protein-rich alternatives to improve the technological properties and functional quality of meat products
    (Elsevier, 2023) Rocchetti, Gabriele; Ferronato, Giulia; Sarv, Viive; Kerner, Kristi; Venskutonis, Petras R; Lucini, Luigi
    In the last years, animal proteins from meat and meat-derived products have represented one of the main concerns to achieve a sustainable food production. Within this perspective, the partial replacement of meat with nonmeat substances having a high- protein content, offers interesting opportunities to reformulate more sustainable meat products characterized also by potential health-promoting properties. Therefore, starting from these background conditions, this short review critically summarizes recent findings on extenders from different origins, namely pulses, plant-based ingredients, plant by-products, and unconventional sources, as valuable possibility to improve the technological profile and functional quality of meat, together with providing a focus on their ability to affect the sustainability of meat products.
  • Kirje
    Evaluation of different blackcurrant seed ingredients in meatballs by using conventional quality assessment and untargeted metabolomics
    (Elsevier, 2023) Kerner, Kristi; Kazernavičiūtė, Rita; Jõudu, Ivi; Rocchetti, Gabriele; Lucini, Luigi; Tänavots, Alo; Hussain, Shehzad; Venskutonis, Petras Rimantas
    Blackcurrants are sources of phenolic compounds, such as anthocyanins, possessing strong antioxidant, anti- microbial and antifungal activity. Therefore, the addition of different blackcurrant pomace ingredients may affect the overall meat quality. The actual chemical profile and bioactivities of blackcurrant pomace ingredients may strongly depend on its preparation; for instance, in our study the highest values of the in vitro antioxidant capacity were determined for blackcurrant seeds after supercritical CO2 extraction. Starting from these back- ground conditions, in this work, we evaluated the ability of three different concentrations (namely 1, 3, and 5% w/w) of blackcurrant (BC) seeds following EtOH/water extraction (BC-AE), before supercritical fluid CO2 extraction (BC-RS), and after supercritical fluid CO2 extraction (BC-ASC) to affect different quality parameters of pork meatballs. These latter were stored considering three different time-points, namely 1, 3 and 6 days at 4 ◦C packed under modified atmosphere (i.e., 70% N2 and 30% CO2). Untargeted metabolomics allowed to identify several lipid and protein-related oxidation products involved in redox reactions, such as 13-L-hydroperoxylino- leic acid, (12S,13S)-epoxylinolenic acid, 9,10-epoxyoctadecenoic acid, glutathione, glutathione disulfide, L- carnosine, L-ascorbic acid, and tocotrienols. Besides, multivariate statistics applied on the metabolomics dataset confirmed that the chemical profile of meatballs was an exclusive combination of both BC inclusion levels and type of BC-ingredients considered. Our findings showed that the higher the concentration of BC seed ingredients in meatballs, the lower the cooking loss and the higher the fibre content. Also, all the ingredients significantly affected the colour parameters.
  • Kirje
    Sustainable polysaccharide and protein hydrogel-based packaging materials for food products: A review
    (Elsevier, 2023) Sudheer, Surya; Bandyopadhyay, Smarak; Bhat, Rajeev
    Sustainable food packaging is a necessary element to ensure the success of a food system, the accomplishment of which is weighed in terms of quality retention and ensured products safety. Irrespective of the raised environmental concerns regarding petroleum-based packaging materials, a sustainable analysis and a lab to land assessment should be a priority to eliminate similar fates of new material. Functionalized bio-based hydrogels are one of the smartest packaging inventions that are expected to revolutionize the food packaging industry. Although in this review, the focus relies on recent developments in the sustainable bio-based hydrogel packaging materials, natural biopolymers such as proteins and polysaccharides from which hydrogels could be obtained, the challenges encountered in hydrogel-based packaging materials and the future prospects of hydrogel-based food packaging materials are also discussed. Moreover, the need for 'Life Cycle Assessment' (LCA), stress on certifications and a sustainable waste management system is also suggested which can bring both food and packaging into the same recycling bins.
  • Kirje
    Phytochemical characterization of oil and protein fractions isolated from Japanese quince (Chaenomeles japonica) wine by-product
    (Elsevier, 2023) Ben-Othman, Sana; Bleive, Uko; Kaldmäe, Hedi; Aluvee, Alar; Rätsep, Reelika; Karp, Kadri; Maciel, Larissa Silva; Herodes, Koit; Rinken, Toonika
    The wine industry generates large quantities of by-products each year. Therefore, this work aimed to isolate and evaluate the oil and protein fractions of Japanese quince (Chaenomeles japonica, JQ) press residue, offering a partial utilization of valuable bioactive compounds of wine industry by-products. To study the JQ oil extract yield, composition and oxidation stability, we modified the co-solvent composition during the supercritical CO2 (SC–CO2) extraction of oil by adding different ethanol content. The remaining defatted material was used for the isolation of proteins. The SC-CO2 extraction yielded oil rich in polyunsaturated fatty acids, tocopherols, and phytosterols. The use of ethanol as a co-solvent increased the oil yield but did not enhance its oxidative stability or content of antioxidants. We recovered protein isolate after removing tannins with 70% ethanol extraction in the next step. The JQ protein isolate contained all essential amino acids. In addition to its balanced amino acid composition, the protein isolate exhibited excellent emulsifying properties highlighting its potential as a food additive. In conclusion, JQ wine by-products can be utilized for the extraction of oil and protein fractions which can be used in food or cosmetic product formulation.
  • Kirje
    Untargeted metabolomics and conventional quality characterization of rowanberry pomace ingredients in meatballs
    (Elsevier, 2023) Sarv, Viive; Kerner, Kristi; Venskutonis, Petras Rimantas; Rocchetti, Gabriele; Becchi, Pier Paolo; Lucini, Luigi; Tänavots, Alo; Bhat, Rajeev
    In this study, a rowanberry pomace defatted with supercritical CO2 (2%-AC), its ethanolic extract (1%-E) and extraction residue (2%-R), were tested in meatball preparation. The meatballs with 1%-E demonstrated the highest in vitro radical scavenging capacity. In the case of 1%-E the pH of meatballs was significantly lower compared to the control sample (P = 0.0132) on the 5-day. The lowest cooking loss was achieved when the meatballs contained mainly fibre-rich 2%-R. The UHPLC method detected 184 metabolites, including strong antioxidants, such as chlorogenic acids, 3′,4′-methylenedioxy-5,7-dimethylepicatechin, hyperin, isoquercitrin. The 1%-E was particularly effective against the development of unpleasant off-flavours caused by carbonyl compounds. Consistently, the decrease in lipid oxidation, indicated by reduced 7-dodecenal and 2,4-heptadienal contents, has been observed following the addition of rowanberry extract to meatballs. Metabolomics coupled with conventional quality evaluations provided a deeper understanding of the potential utilization and valor- isation of different rowanberry pomace extracts as meat ingredients.
  • Kirje
    Antioxidants Characterization of the Fruit, Juice, and Pomace of Sweet Rowanberry (Sorbus aucuparia L.) Cultivated in Estonia
    (MDPI, 2021) Sarv, Viive; Venskutonis, Petras Rimantas; Rätsep, Reelika; Aluvee, Alar; Kazernavičiūtė, Rita; Bhat, Rajeev; Polli Horticultural Research Centre, Institute of Agricultural and Environmental Sciences. Estonian University of Life Sciences; ERA Chair for Food (By-) Products Valorisation Technologies (VALORTECH). Estonian University of Life Sciences
    This study aimed to identify promising candidates of rowanberry cultivars for a wider cultivation and utilization. Antioxidant properties and phenolic content were evaluated for fruit, juice, and pomace samples of 16 different sweet rowanberry cultivars (cvs) and wild rowanberry (S. aucuparia L.), while the antioxidant potential was assessed using three different methods, based on the capacity to scavenge ABTS + and DPPH and measure the oxygen radical absorbance capacity (ORAC). In general, the radical scavenging capacity was higher for hybrid cultivars, e.g., for cvs Likernaja, Burka, Granatnaja, and Rubinovaja in all assays. The highest value in the ABTS + assay was determined for the fruit sample Likernaja, and in DPPH assay in the pomace sample of cv. Likernaja, at 527.55 and 1068.28 M TE/g dw, respectively. The highest ORAC value was found in the fruit sample of Burka (456.53 M TE/g dw). Among the Nevezhino rowans, the highest radical scavenging values of all fractions were determined in cv. Solnechnaja. Regarding the total phenolic content (TPC), higher values were obtained in the whole fruits than in separated fractions, juice, and pomace. The tested hybrids had higher TPC values, either in fruit and pomace or in juice extracts, than those in the other analyzed S. aucuparia L. cultivars. While the fruit and juice samples showed higher anthocyanin (ACY) values, the pomace samples had higher hydroxycinnamic acid (HCA) contents on average. The results revealed that the different fractions of selected rowanberry cultivars can be a promising source of antioxidants and polyphenols for further potential applications. It is envisaged that the results of this study will serve in valorizing sweet rowanberry cultivars as value-added functional ingredients for food and non-food applications.
  • Kirje
    Application of Raw and Defatted by Supercritical CO₂ Hemp Seed Press-Cake and Sweet Grass Antioxidant Extract in Pork Burger Patties
    (MDPI, 2021) Kerner, Kristi; Jõudu, Ivi; Tänavots, Alo; Venskutonis, Petras Rimantas; Chair of Food Science and Technology, Institute of Veterinary Medicine and Animal Sciences. Estonian University of Life Sciences; ERA Chair for Food (By-) Products Valorisation Technologies (VALORTECH). Estonian University of Life Sciences; Chair of Animal Breeding and Biotechnology, Institute of Veterinary Medicine and Animal Sciences. Estonian University of Life Sciences
    There is an increasing tendency toward the application of plant origin ingredients in meat products. This study evaluates the physicochemical properties and oxidative stability of pork burger patties produced with the addition of dried raw and defatted by supercritical CO2 extraction hemp seed press-cake as protein-rich ingredients (1.5–2.0%) and sweet grass ethanolic extract (0.5%) as a strong natural antioxidant. The main aim of using such a combination was to assess the possibility of mitigating the negative effects of hemp seed press-cake, containing approx. 10% of highly unsaturated oil, on the oxidation of meat products. The patties were compared with the control sample (without additives) during storage on days 0, 4, 8, 15, and 21 at 4 °C in modified atmosphere conditions. Plant ingredients reduced the lightness of pork patties, while their effects on other physicochemical characteristics were insignificant. The patties with fully defatted hemp seed flour showed the lowest grilling losses. Based on the measurement of thiobarbituric acid reactive substances, raw hemp seed press-cake increased the oxidative rate of pork patties; however, remarkably, the addition of sweet grass extract completely inhibited oxidation during the whole period of storage. The sensory characteristics of the products were acceptable; however, the patties with sweet grass extract received lower evaluation scores.
  • Kirje
    Bio-Based Formulations for Sustainable Applications in Agri-Food-Pharma
    (MDPI, 2021) Sharma, Minaxi; Bhat, Rajeev; Usmani, Zeba; McClements, David Julian; Shukla, Pratyoosh; Raghavendra, Vinay B.; Gupta, Vijai Kumar; Food (By-) Products Valorisation Technologies (VALORTECH) ERA Chair. Estonian University of Life Sciences
    Currently, there is a strong enduring interest towards obtaining high-value, sustainable bio-based bioactive compounds from natural resources, as there is great demand for these compounds in various market sectors such as agriculture, food, pharma, cosmeceuticals, and others. This demand has encouraged researchers to isolate, identify and characterize novel natural bioactive compounds with potential therapeutic and commercial values with industrial importance [1]. These bioactive compounds are generally secondary metabolites (synthesized via plant biosynthetic pathways) and include polyphenols, carotenoids, flavonoids, sterols, dietary fiber, essential vitamins, coenzyme Q, phytosterols, glucosinolates and others with potential beneficial roles as nutraceuticals, surfactants and bio-stimulants. Understanding the molecular characteristics, physicochemical properties, biological activity, and stability of these bioactives under different conditions is vital for their commercial exploitation. The efficacy of these bioactives can often be improved by encapsulating them in nanobased-formulations designed for application in the agriculture, food, pharmaceutical industries. These delivery systems can be designed to increase the dispersibility, stability, bioavailability, and bioactivity imparted by the bioactives. Moreover, they may be useful for minimizing undesirable side-effects, facilitating targeted delivery to certain cells, and enhancing the shelf life of food products. The bioactive molecules are partly or wholly derived from resources of biological origin mainly those of plants, animal and microbial resources (e.g., biomass/feed stock from agri-food sector, food wastes and by-products, algae, marine organisms, etc.). These molecules have recently emerged on the global market as a highly reliable environmentally friendly alternative to chemically synthesized compounds. The natural bioactive compounds provide additional benefits to health and overall wellbeing beyond basic nutrition. For instance, bioactive compounds have been well established for their antioxidant, antimicrobial, antiviral, anticancer, anti-hypertensive and other biological activities under in vitro and in vivo conditions. The isolation, purification and safety efficacy of these compounds obtained from natural resources is a vital criterion that needs to be considered.
  • Kirje
    Immobilization of Pectinolytic Enzymes on Nylon 6/6 Carriers
    (MDPI, 2021) Ben-Othman, Sana; Rinken, Toonika; ERA Chair for Food (By-) Products Valorisation Technologies Valortech. Estonian University of Life Sciences
    Pectinolytic enzymes are an important tool for sustainable food production, with a wide range of applications in food processing technologies as well as the extraction of bioactive compounds from pectin-rich raw materials. In the present study, we immobilized commercial pectinase preparation onto pellet and thread shaped nylon 6/6 carriers and assessed its stability and reusability. Five commercial pectinase preparations were tested for different pectin de-polymerizing activities (pectinase, polygalacturonase, and pectin lyase activities). Thereafter, Pectinex® Ultra Tropical preparation, exhibiting the highest catalytic activities among the studied preparations (p < 0.0001), was immobilized on nylon 6/6 using dimethyl sulfate and glutaraldehyde. The immobilization yield was in accordance with the carrier surface area available for enzyme attachment, and it was 1.25 0.10 U/g on threads, which was over 40 times higher than that on pellets. However, the inactivation of immobilized enzymes was not dependent on the shape of the carrier, indicating that the attachment of the enzymes on the surface of nylon 6/6 carriers was similar. The half-life of enzyme inactivation fast phase at 4 C was 12.8 days. After 5 weeks, the unused threads retained 63% of their initial activity. Reusability study showed that after 20 successive cycles the remaining activity of the immobilized pectinase was 22%, indicating the good prospects of reusability of the immobilized enzyme preparations for industrial application.
  • Kirje
    Engineered Microbes for Pigment Production Using Waste Biomass
    (Bentham Science Publishers, 2020) Usmani, Zeba; Sharma, Minaxi; Sudheer, Surya; Gupta, Vijai K.; Bhat, Rajeev; ERA Chair for Food (By-) Products Valorization Technologies-VALORTECH. Estonian University of Life Sciences
    Agri-food waste biomass is the most abundant organic waste and has high valorisation potential for sustainable bioproducts development. These wastes are not only recyclable in nature but are also rich sources of bioactive carbohydrates, peptides, pigments, polyphenols, vitamins, natural antioxidants, etc. Bioconversion of agri-food waste to value-added products is very important towards zero waste and circular economy concepts. To reduce the environmental burden, food researchers are seeking strategies to utilize this waste for microbial pigments production and further biotechnological exploitation in functional foods or value-added products. Microbes are valuable sources for a range of bioactive molecules, including microbial pigments production through fermentation and/or utilisation of waste. Here, we have reviewed some of the recent advancements made in important bioengineering technologies to develop engineered microbial systems for enhanced pigments production using agrifood wastes biomass/by-products as substrates in a sustainable way.
  • Kirje
    Valorisation of Sea Buckthorn Pomace by Optimization of Ultrasonic-Assisted Extraction of Soluble Dietary Fibre Using Response Surface Methodology
    (MDPI, 2021) Hussain, Shehzad; Sharma, Minaxi; Bhat, Rajeev
    Sea buckthorn pomace is a valuable industrial waste/by-product obtained after juice production that contains bioactive, health-promoting dietary fibres. This pomace finds usage as animal feed or simply discarded, owed to the lack of appropriate handling or processing facilities. The present study was aimed to evaluate the effects of green extraction technologies such as ultrasonic- assisted extraction on the yield of soluble dietary fibre (SDF) from sea buckthorn pomace. Response surface methodology (RSM) coupled with Box–Behnken design (BBD) was applied for optimization of SDF yield. The effects of sonication temperature (60–80 ◦C), sonication power (100–130 W) and extraction time (30–60 min) on the yield of SDF were also investigated. Furthermore, colour measure- ment and hydration properties of sea buckthorn pomace powder (STP) and dietary fibre fractions (SDF and insoluble dietary fibre, IDF) were also investigated. From the RSM results, the optimal sonication temperature (67.83 ◦C), sonication power (105.52 W) and extraction time (51.18 min) were identified. Based on this, the modified optimum conditions were standardised (sonication tempera- ture of 70 ◦C, sonication power of 105 W and extraction time of 50 min). Accordingly, the yield of SDF obtained was 16.08 ± 0.18%, which was close to the predicted value (15.66%). Sonication temperature showed significant effects at p ≤ 0.01, while sonication power and extraction time showed significant effects at p ≤ 0.05 on the yield of SDF. The result on colour attributes of STP, SDF and IDF differed (L* (STP: 54.71 ± 0.72, IDF: 72.64 ± 0.21 and SDF: 54.53 ± 0.31), a* (STP: 52.35 ± 1.04, IDF: 32.85 ± 0.79 and SDF: 43.54 ± 0.03), b* (STP: 79.28 ± 0.62, IDF: 82.47 ± 0.19 and SDF: 71.33 ± 0.50), and ∆E* (STP: 79.93 ± 0.50, IDF: 74.18 ± 0.30 and SDF: 68.40 ± 0.39)). Higher values of hydration properties such as the water holding, swelling and oil holding capacities were found in SDF (7.25 ± 0.10 g g−1, 7.24 ± 0.05 mL g−1 and 1.49 ± 0.02 g g−1), followed by IDF (6.30 ± 0.02, 5.75 ± 0.07 and 1.25 ± 0.03) and STP (4.17 ± 0.04, 3.48 ± 0.06 and 0.89 ± 0.03), respectively. Based on our results, response surface methodology is recommended to be adopted to optimize the ultrasonic-assisted extraction to obtain maximum yield of SDF from sea buckthorn pomace. These results can be of practical usage while designing future functional food formulations using sea buckthorn pomace.
  • Kirje
    Optimization of Ultrasound-Assisted Extraction of Phloretin and Other Phenolic Compounds from Apple Tree Leaves (Malus domestica Borkh.) and Comparison of Different Cultivars from Estonia
    (MDPI, 2021) Ben-Othman, Sana; Kaldmäe, Hedi; Rätsep, Reelika; Bleive, Uko; Aluvee, Alar; Rinken, Toonika
    Polyphenolic compounds, plant secondary metabolites essential for plant survival, are known for their high antioxidant and anti-inflammatory activity. In addition, several polyphenols, such as phloretin, also have potential antiviral effects, making these compounds potential ingredients of biofunctional foods. A promising source for the extraction of phloretin is a by-product of apple production—apple tree leaves. Focusing on green technologies, the first aim of the present study was to optimize the direct ultrasound-assisted extraction conditions to gain the maximum yield of phloretin from air-dried apple leaves. For the optimization of process parameters, we applied the response surface method with Box–Behnken design. The optimal extraction conditions were extraction time 14.4 min, sonication amplitude 10% and 10 g of sample per 100 mL solvent (70% ethanol, w/w). Using these conditions, we assessed the content of individual and total polyphenolic compounds along with antioxidant activity in the leaves of different autumn and winter apple cultivars grown in Estonia. The analyses were carried out with chromatographic (HPLC-DADMS/ MS) and spectrophotometric methods. The phloretin concentration ranged from 292 to 726 g/g and antioxidant activity from 6.06 to 11.42 mg GA eq./g, these being the highest in the local winter cultivars ‘Paide taliõun’ and ‘Tellissaare’, respectively.