High pressure homogenization to boost the technological functionality of native pea proteins.

Pea proteins are being increasingly used for the formulation of plant-based products, but their globular structure and the presence of aggregates can affect their technological properties. In this study, the effect of high pressure homogenization (HPH) at different intensities (60 and 100 MPa) was investigated as a pre-treatment to modulate the techno-functional properties of a pea protein isolate (IP) extracted through an alkaline extraction/isoelectric precipitation process. SDS-PAGE, circular dichroism, thermal properties, total free sulfhydryl groups, antioxidant capacity and reducing properties were evaluated along with technological indices as solubility, WHC and OHC, interfacial tension and emulsifying capacity. HPH treatments were able to unfold and modify proteins structure, leading also to a change of the relative abundance of pea protein globulins (SDS-PAGE) and of the vicilin to legumin ratio. Solubility, WHC and OHC were improved, while interfacial tension and emulsifying capacity were weakly affected. However, an enhanced physical stability over time of the emulsions prepared with the 60 MPa-treated protein was found, likely as an effect of the decreased ratio between vicilin and legumin after treatment. Results of this study will contribute to deepen the effect of the HPH technology used as pre-treatment, adding useful results and expanding knowledge about the structure and techno-functional properties of native and modified pea proteins.

Conventional and innovative extraction technologies to produce food-grade hop extracts: Influence on bitter acids content and volatile organic compounds profile.

Hop extracts represent a natural alternative to synthetic food additives because of their high content of bitter acids and volatile organic compounds (VOCs) with bittering, flavoring, and antimicrobial properties. However, broader uses of hop extracts as natural techno-functional ingredients rely on the identification of sustainable and affordable extraction technologies allowing to diversify the processes and produce extracts characterized by different compositions and, consequently, qualitative properties. Thus, this study is aimed to evaluate and compare the effect of innovative and conventional extraction methods on the bitter acids content and VOCs pattern of food-grade ethanolic hop extracts for food applications. Innovative extractions were carried out by using two ultrasound systems (a laboratory bath [US] and a high-power ultrasound bath [HPUS]), and a high-pressure industrial process (high hydrostatic pressure [HHP]). Conventional extractions (CONV) were performed under dynamic maceration at 25 and 60°C; for ultrasound and conventional methods, the effect of the extraction time was also investigated. Among the extracts, the highest and lowest content of bitter acids was found in CONV 60°C extracts, and HHP and CONV 25°C extracts, respectively. Of the 34 VOCs identified in dry hops, ∼24 compounds were found in US, HPUS and CONV extracts, while only 18 were found in HHP. CONV extractions showed higher selectivity for sesquiterpenes, while US and HPUS showed higher selectivity for esters and monoterpenes. Hierarchical cluster analysis (HCA) and partial least squares-discriminant analysis (PLS-DA) allowed classifying hop extracts based on the extraction methods and also allowed highlighting the technological conditions to produce hop extracts with specific techno-functional and flavoring properties. PRACTICAL APPLICATION: The study showed that different extraction methods can lead to hop products with varying sensory and functional properties. By selecting the right extraction method, companies can produce hop extracts with specific compositions that meet their needs for clean label and sustainable food products, as well as new edible packaging or coatings.

Freeze-Drying Microencapsulation of Hop Extract: Effect of Carrier Composition on Physical, Techno-Functional, and Stability Properties.

In this study, freeze-drying microencapsulation was proposed as a technology for the production of powdered hop extracts with high stability intended as additives/ingredients in innovative formulated food products. The effects of different carriers (maltodextrin, Arabic gum, and their mixture in 1:1 w/w ratio) on the physical and techno-functional properties, bitter acids content, yield and polyphenols encapsulation efficiency of the powders were assessed. Additionally, the powders' stability was evaluated for 35 days at different temperatures and compared with that of non-encapsulated extract. Coating materials influenced the moisture content, water activity, colour, flowability, microstructure, and water sorption behaviour of the microencapsulates, but not their solubility. Among the different carriers, maltodextrin showed the lowest polyphenol load yield and bitter acid content after processing but the highest encapsulation efficiency and protection of hop extracts' antioxidant compounds during storage. Irrespective of the encapsulating agent, microencapsulation did not hinder the loss of bitter acids during storage. The results of this study demonstrate the feasibility of freeze-drying encapsulation in the development of functional ingredients, offering new perspectives for hop applications in the food and non-food sectors.

Bio-aerogels: Fabrication, properties and food applications.

Traditional inorganic aerogels sustainability, biodegradability, and environmental safety concerns have driven researchers to find their safe green alternatives. Recently, interest in the application of bio-aerogels has rapidly increased in the food industry due to their unique characteristics such as high specific surface area and porosity, ultralow density, tunable pore size and morphology, and superior properties (physicochemical, mechanical, and functional). Bio-aerogels, a special category of highly porous unique materials, fabricated by the sol-gel method followed by drying processes, comprising three-dimensional networks of interconnected biopolymers (e.g., polysaccharides and proteins) with numerous air-filled pores. The production of bio-aerogels begins with the formation of a homogeneously dispersed precursor solution, followed by gelation and wet gel drying procedures by employing special drying techniques including atmospheric-, freeze-, and supercritical drying. Due to their special properties, bio-aerogels have emerged as sustainable biomaterial for many industrial applications, i.e., encapsulation and controlled delivery, active packaging, heavy metals separation, water and air filtration, oleogels, and biosensors. Bio-aerogels are low-cost, biocompatible, and biodegradable sustainable material that can be used in improving the processing, storage, transportation, and bioavailability of food additives, functional ingredients, and bioactive substances for their health benefits with enhanced shelf-life.

Starch-based sustainable hydrogel loaded with Crocus sativus petals extract: A new product for wound care.

The aim of the present study was to valorize Crocus sativus petals, the main waste deriving from saffron stigma harvesting, as source of bioactive molecules to be used in health field. Three different dry extracts were prepared by eco-friendly methods (maceration and ultrasound bath assisted maceration) using saffron petals as raw material and ethanol 70 % either ethanol 96 % as extraction solvents. A preliminary evaluation of the antioxidant activity (measured by ABTS*+, DPPH* and FRAP) highlighted that the most suitable extraction solvent is represented by ethanol 70 %. By in vitro studies on keratinocytes emerged that the extract obtained by maceration (rich in gallic and chlorogenic acids) stimulates their growth in a safe concentration range (0.02-0.4 mg/mL) suggesting a potential application in skin diseases such as superficial wounds. Due to the low manageability, the extract was firstly supported on corn starch powder particles and then formulated as starch gel. The obtained formulation showed both suitable rheological properties and spreadability necessary for an easy and pain free application on damaged skin. Moreover, in vitro microbiological studies of starch gel demonstrated antimicrobial activity toward S. epidermidis and self-preserving capacity.

Degradation kinetics of C-Phycocyanin under isothermal and dynamic thermal treatments.

C-Phycocyanin (C-PC) represents an alternative to artificial blue/green dyes in food products. This study characterized and gained insights into C-PC thermal stability mechanisms and provided a model to estimate its thermal degradation. Aqueous solutions of C-PC (0.3 µM, pH:6.1) were isothermally heated at 45-80 °C. C-PC degradation was monitored based on the photophysical properties of its lumiphores (phycocyanobilins and aromatic aminoacids-AAs). While C-PC was stable at 45 °C, less than 10 min at 80 °C sufficed to degrade most of it. The thermal degradation curves were characterized using the Weibull model, which was validated with data obtained under non-isothermal conditions. Deviations between estimated and experimental values were lower than 8%. Hypsochromic shifts of the AAs' spectra (from 340 to 315 nm) and increase (>30%) in anisotropy at λexc = 280 and 520 nm suggest that colour losses are not solely associated with alterations of the chromophore but also with conformational changes and possible aggregation of the protein subunits.

Hazelnut Shells as Source of Active Ingredients: Extracts Preparation and Characterization.

Hazelnut shells represent a waste material (about 42% of the total biomass) deriving from hazelnut harvest. These are mainly used as a heating source; however, they represent an interesting source of polyphenols useful in health field. The impact on phenolic profile and concentrations of hazelnut shell extracts obtained by three extraction methods (maceration, ultrasonic bath, and high-power ultrasonic), as well as temperature, extraction time, and preventive maceration, was studied. The prepared extracts were characterized in terms of chemical composition, antioxidant and antimicrobial activities. Eighteen different phenolic compounds were identified and quantified by chemical analysis and gallic acid was the most abundant in all the extracts analyzed. Other relevant compounds were chlorogenic acid, protocatechuic acid and catechin. Preventive maceration had a positive effect on the extraction of different types of compounds regardless of the method performed. Application of the high-power ultrasonic method had different effects, either positive or negative, depending on the type of compound and extraction time. All the prepared extracts showed antioxidant activity especially those prepared by maceration, and many of them were able to inhibit the growth of both B. subtilis and B. cereus.

Antioxidant Activity in Frozen Plant Foods: Effect of Cryoprotectants, Freezing Process and Frozen Storage.

The antioxidant activity (AOA) of plant foods is recognized as an index of the potential health benefits resulting from their consumption. Due to their high perishability and seasonality, plant foods are largely consumed or used as processed products and freezing is one of the technologies used for the production of high-quality foods. However, cell breakages occurring during freezing and frozen storage can lead to the release of antioxidant compounds and their degradation due to chemical and enzymatic oxidation reactions, and thus, they could present a lower antioxidant activity compared to the corresponding fresh product. In this context, process conditions, freezing pre-treatments and the use of cryoprotectants can limit the extent of freeze-induced damages and preserve the antioxidant activity of plant foods. This review collects and discusses the state-of-the-art knowledge on the single and combined effect of freezing and frozen storage conditions on the antioxidant activity of fruits and vegetables as well as the role of cryoprotectants. Classes of compounds responsible for the antioxidant activity of plant foods and the most common methods used for the evaluation of the antioxidant activity in vitro are also presented. The freezing principles and the effects of ice nucleation and crystallization on fruits, vegetables and their main derivatives (juices, pulps) have been addressed to highlight their impact on the AOA of plant foods. The effect of freezing and frozen storage on the AOA of plant foods resulted dependant on a series of intrinsic factors (e.g., composition and structure), while the role of extrinsic processing-related factors, such as freezing and storage temperatures, is ambiguous. In particular, many conflicting results are reported in the literature with a high variability depending on the method of analysis used for the AOA evaluation and data expression (fresh or dry weight). Other intrinsic raw material properties (e.g., cultivar, ripening degree), post-harvest conditions, as well as defrosting methods that in the majority of the studies are scarcely reported, contribute to the aforementioned discrepancies. Finally, due to the limited number of studies reported in the literature and the high variability in product processing, the effect of cryoprotectants on the AOA of plant foods remains unclear.

Whole genome integrity and enhanced developmental potential in ram freeze-dried spermatozoa at mild sub-zero temperature.

Freeze-dried spermatozoa typically shows a reduction in fertility primarily due to the DNA damage resulting from the sublimation process. In order to minimize the physical/mechanical damage resulting from lyophilization, here we focused on the freezing phase, comparing two cooling protocols: (i) rapid-freezing, where ram sperm sample is directly plunged into liquid nitrogen (LN-group), as currently done; (ii) slow-freezing, where the sample is progressively cooled to - 50 °C (SF-group). The spermatozoa dried in both conditions were analysed to assess residual water content by Thermal Gravimetric Analysis (TGA) and DNA integrity using Sperm Chromatin Structure Assay (SCSA). TGA revealed more than 90% of water subtraction in both groups. A minor DNA damage, Double-Strand Break (DSB) in particular, characterized by a lower degree of abnormal chromatin structure (Alpha-T), was detected in the SF-group, comparing to the LN-one. In accordance with the structural and DNA integrity data, spermatozoa from SF-group had the best embryonic development rates, comparing to LN-group: cleaved embryos [42/100 (42%) versus 19/75 (25.3%), P < 0.05, SL and LN respectively] and blastocyst formation [7/100 (7%) versus 2/75 (2.7%), P < 0.05, SF and LN respectively]. This data represents a significant technological advancement for the development of lyophilization as a valuable and cheaper alternative to deep-freezing in LN for ram semen.

From by-product to food ingredient: evaluation of compositional and technological properties of olive-leaf phenolic extracts.

BACKGROUND: Most olive by-products, like olive leaves, are still undervalued despite their strong potential as a source of healthy and functional components. To exploit their potential use as active ingredients in complex food systems, it is of primary importance the knowledge of their composition and technological functionality which represented the objective of this work. RESULTS: Phenolic extracts from olive leaves, obtained by extraction with pure water (Eth0) and two different water-ethanol solutions (Eth30, Eth70), were characterized for their composition and technological properties such as water- / oil- holding ability, air/water surface activity, and emulsifying capacity at pH 4.5 and 7. Their chemical stability over time, at constant temperature, was also investigated. The technological properties were affected by extraction media and pH. Phenolic extracts displayed significant surface activity, showing dose-dependent behavior. Surface properties were affected by pH and this result was confirmed by the emulsifying capacity. The extracts showed good oil-holding capacity but limited water-binding capacity. Eth70 showed the highest chemical stability, which was confirmed by the rate parameters obtained by modeling data using a Weibull model. CONCLUSION: The results of this study highlight that olive leaves extracts can represent a useful ingredient in acidic lipid-containing foods. © 2019 Society of Chemical Industry.

Effect of Dipping and Vacuum Impregnation Pretreatments on the Quality of Frozen Apples: A Comparative Study on Organic and Conventional Fruits.

The effect of dipping and vacuum impregnation (VI) pretreatments with lemon juice solution on the quality and stability of organic and conventional frozen apples was investigated. Fresh apples were characterized; organic apples showed, at equal starch and ripeness index, a lower sugar content, and higher acidity than conventional ones. The polyphenol content was slightly higher in organic apples than in conventional ones while polyphenoloxidase activity was similar. No differences in color and firmness were evidenced. Dipping affected organic and conventional apples' color by determining an increase of lightness (ΔL* ≈ 4) and h° (Δh° ≈ 6) parameters. VI reduced the lightness of apples (ΔL* ≈ -3) but the addition of lemon juice counterbalanced the lightness reduction by increasing ΔL* from 3 to 1.5 ca. Pretreatments did not affect the firmness of organic fruits while impaired that of the conventional ones ( 26% on average), likely due to different fruit matrix porosity and cell wall composition. Freezing (-40 °C) and frozen storage (up to 300 days) dramatically reduced the firmness of organic (42%) and conventional products (58%). At equal pretreatment and storage time (that is, 15, 30, 300 days), higher firmness retention was evidenced in organic apples than in conventional ones. All through frozen storage, VI was shown to better preserve the mechanical properties of organic apples than that of conventional ones. Both freezing and frozen storage reduced the hue of frozen apple products by up to 8% due to browning reactions. Lemon juice addition increased the hue of both frozen samples and thawed samples by about 2% all through storage time.