Extrusion cooking of protein-based products: potentials and challenges.

Extrusion cooking is receiving increasing attention as technology applied for the production of protein-based products. Researchers in this field showed that proteins from several sources are barely consumed because of their poor functionality and lack of acceptability related to the presence of some antinutritional factors. In this regard, extrusion is becoming of key importance thanks to its ability to improve protein functional properties. Based on this remarkable advantage, several studies have been published so far providing evidence of the enhanced functional, physicochemical and sensory properties of protein-based extruded products. The objective of the present review is to give a detailed overview of the potential of extrusion for the production of protein-based products. More specifically, the work describes all the studies published so far on vegetable and animal proteins including those recently released applying the technology on insect proteins. The aspects related to the functional properties of the extrudates together with the quality changes occurring during the process are also described to highlight the potential of the technology for future applications.

In Vivo Anti-Inflammatory Effect, Antioxidant Activity, and Polyphenolic Content of Extracts from Capsicum chinense By-Products.

By-products of Capsicum chinense Jacq., var Jaguar could be a source of bioactive compounds. Therefore, we evaluated the anti-inflammatory effect, antioxidant activity, and their relationship with the polyphenol content of extracts of habanero pepper by-products obtained from plants grown on black or red soils of Yucatán, Mexico. Moreover, the impact of the type of extraction on their activities was evaluated. The dry by-product extracts were obtained by maceration (ME), Soxhlet (SOX), and supercritical fluid extraction (SFE). Afterward, the in vivo anti-inflammatory effect (TPA-induced ear inflammation) and the in vitro antioxidant activity (ABTS) were evaluated. Finally, the polyphenolic content was quantified by Ultra-Performance Liquid Chromatography (UPLC), and its correlation with both bioactivities was analyzed. The results showed that the SFE extract of stems of plants grown on red soil yielded the highest anti-inflammatory effect (66.1 ± 3.1%), while the extracts obtained by ME and SOX had the highest antioxidant activity (2.80 ± 0.0052 mM Trolox equivalent) and polyphenol content (3280 ± 15.59 mg·100 g-1 dry basis), respectively. A negative correlation between the anti-inflammatory effect, the antioxidant activity, and the polyphenolic content was found. Overall, the present study proposed C. chinense by-products as a valuable source of compounds with anti-inflammatory effect and antioxidant activity.

Encapsulation of Lipid-Soluble Bioactives by Nanoemulsions.

Lipid-soluble bioactives are important nutrients in foods. However, their addition in food formulations, is often limited by limited solubility and high tendency for oxidation. Lipid-soluble bioactives, such as vitamins A, E, D and K, carotenoids, polyunsaturated fatty acids (PUFA) and essential oils are generally dispersed in water-based solutions by homogenization. Among the different homogenization technologies available, nanoemulsions are one of the most promising. Accordingly, this review aims to summarize the most recent advances in nanoemulsion technology for the encapsulation of lipid-soluble bioactives. Modern approaches for producing nanoemulsion systems will be discussed. In addition, the challenges on the encapsulation of common food ingredients, including the physical and chemical stability of the nanoemulsion systems, will be also critically examined.

Antimicrobial Effect of Picea abies Extracts on E. coli Growth.

This study aims to investigate the effect of essential oils extracted from wood residues of Picea abies on the growth of Escherichia coli. The essential oils were extracted by supercritical carbon dioxide, leading to a yield of 3.4 ± 0.5% (w/w) in 120 min. The antimicrobial effect was tested at 37 °C by isothermal calorimetry. The heat-flow (dq/dt vs. time) was integrated to give a fractional reaction curve (α vs. time). Such curves were fitted by a modified Gompertz function to give the lag-time (λ) and the maximum growth rate (µmax) parameters. The results showed that λ was linearly correlated with E. coli concentration (λ = 1.4 h/log (CFU/mL), R2 = 0.997), whereas µmax was invariant. Moreover, the overall heat was nearly constant to all the dilutions of E. coli. Instead, when the essential oil was added (with concentrations ranging from 1 to 5 mg/L) to a culture of E. coli (104 CFU/mL), the lag-time increased from 14.1 to 33.7 h, and the overall heat decreased from 2120 to 2.37 J. The results obtained by the plate count technique were linear with the lag-time (λ), where (λ = -7.3 × log (CFU/mL) + 38.3, R2 = 0.9878). This suggested a lower capacity of E. coli to metabolize the substrate in the presence of the essential oils. The results obtained in this study promote the use of essential oils from wood residues and their use as antimicrobial products.

Current technologies and new insights for the recovery of high valuable compounds from fruits by-products.

The recovery of high valuable compounds from food waste is becoming a tighten issue in food processing. The large amount of non-edible residues produced by food industries causes pollution, difficulties in the management, and economic loss. The waste produced during the transformation of fruits includes a huge amount of materials such as peels, seeds, and bagasse, whose disposal usually represents a problem. Research over the past 20 years revealed that many food wastes could serve as a source of potentially valuable bioactive compounds, such as antioxidants and vitamins with increasing scientific interest thanks to their beneficial effects on human health. The challenge for the recovery of these compounds is to find the most appropriate and environment friendly extraction technique able to achieve the maximum extraction yield without compromising the stability of the extracted products. Based on this scenario, the aim of the current review is twofold. The first is to give a brief overview of the most important bioactive compounds occurring in fruit wastes. The second is to describe the pro and cons of the most up-to-dated innovative and environment friendly extraction technologies that can be an alternative to the classical solvent extraction procedures for the recovery of valuable compounds from fruit processing. Furthermore, a final section will take into account published findings on the combination of some of these technologies to increase the extracts yields of bioactives.

Supercritical CO2 induces marked changes in membrane phospholipids composition in Escherichia coli K12.

Supercritical carbon dioxide (SC-CO2) treatment is one of the most promising alternative techniques for pasteurization of both liquid and solid food products. The inhibitory effect of SC-CO2 on bacterial growth has been investigated in different species, but the precise mechanism of action remains unknown. Membrane permeabilization has been proposed to be the first event in SC-CO2-mediated inactivation. Flow cytometry, high performance liquid chromatography­electrospray ionization­mass spectrometry and NMR analyses were performed to investigate the effect of SC-CO2 treatment on membrane lipid profile and membrane permeability in Escherichia coli K12. After 15 min of SC-CO2 treatment at 120 bar and 35 °C, the majority of bacterial cells dissipated their membrane potential (95 %) and lost membrane integrity, as 81 % become partially permeabilized and 18 % fully permeabilized. Membrane permeabilization was associated with a 20 % decrease in bacterial biovolume and to a strong (>50 %) reduction in phosphatidylglycerol (PG) membrane lipids, without altering the fatty acid composition and the degree of unsaturation of acyl chains. PGs are thought to play an important role in membrane stability, by reducing motion of phosphatidylethanolamine (PE) along the membrane bilayer, therefore promoting the formation of inter-lipid hydrogen bonds. In addition, the decrease in intracellular pH induced by SC-CO2 likely alters the chemical properties of phospholipids and the PE/PG ratio. Biophysical effects of SC-CO2 thus cause a strong perturbation of membrane architecture in E. coli, and such alterations are likely associated with its strong inactivation effect.

Microalgae Proteins as Sustainable Ingredients in Novel Foods: Recent Developments and Challenges.

Microalgae are receiving increased attention in the food sector as a sustainable ingredient due to their high protein content and nutritional value. They contain up to 70% proteins with the presence of all 20 essential amino acids, thus fulfilling human dietary requirements. Microalgae are considered sustainable and environmentally friendly compared to traditional protein sources as they require less land and a reduced amount of water for cultivation. Although microalgae's potential in nutritional quality and functional properties is well documented, no reviews have considered an in-depth analysis of the pros and cons of their addition to foods. The present work discusses recent findings on microalgae with respect to their protein content and nutritional quality, placing a special focus on formulated food products containing microalgae proteins. Several challenges are encountered in the production, processing, and commercialization of foods containing microalgae proteins. Solutions presented in recent studies highlight the future research and directions necessary to provide solutions for consumer acceptability of microalgae proteins and derived products.

Determination of free and bound antioxidants in Kamut® wheat by HPLC with triple detector (DAD-CAD-MS).

Kamut® wheat (Triticum turgidum ssp. turanicum), an ancient, underutilized cereal, offers potential health benefits due to its phenolic compounds. This study aimed to investigate the antioxidant potential of Kamut® wheat's free and bound phenolic extracts using an HPLC system equipped with three detectors. The bound extracts, released after alkaline hydrolysis, exhibited higher total phenolic and flavonoid content compared to the free extracts (p < 0.05). The total antioxidant capacity of bound extracts was six-fold greater than in free extracts (p < 0.05). The main antioxidants in free extracts were tyrosine, phenylalanine, tryptophan, and apigenin. In bound extracts, ferulic acid, its dimers and trimer were present. Kamut® wheat exhibited a source of dietary antioxidants and should be considered a potential ingredient for the development of functional foods. Also, the HPLC-triple detector system is effective for in-depth profiling of antioxidant compounds, paving the way for future research on similar grains.

Early detection of acrolein precursors in vegetable oils by using proton transfer reaction - mass spectrometry.

Acrolein is a toxic volatile compound derived from oxidative processes, that can be formed in foods during storage and cooking. This study employs proton transfer reaction mass spectrometry (PTR-MS) to detect acrolein precursors in vegetable oils by focusing on the m/z (mass-to-charge ratio) 57. To this purpose, hempseed, sesame, walnut, olive and linseed oils were stored for 168 h at 60 °C in presence of 2,2'-azobis(2-metilpropionitrile) (3 mM) radicals initiator. The evolution of m/z 57 by PTR-MS was also compared with traditional lipid oxidation indicators such as peroxide value, conjugated diene, oxygen consumption and, isothermal calorimetry. The obtained results were explained by the fatty acid composition and antioxidant capacity of the oils. Hempseed fresh oil presented a very low total volatile organic compounds (VOCs) intensity (5.6 kncps). Nonetheless, after storage the intensity increased ∼70 times. A principal component analysis (PCA) confirmed the potential of m/z 57 to differentiate fresh versus rancid hempseed oil sample. During an autoxidation experiment oils high in linolenic and linoleic acids showed higher m/z 57 emissions and shorter induction times: linseed oil (38 h) > walnut oil (47 h) > hempseed oil (80 h). The m/z 57 emission presented a high correlation coefficient with the total VOC signal (r > 0.95), conjugated dienes and headspace oxygen consumption. A PCA analysis showed a complete separation of the fresh oils on the first component (most significant) with the exception of olive oil. Walnut, hempseed and linseed oil were placed on the extreme right nearby total VOCs and m/z 57. The results obtained highlight the potential of PTR-MS for the early detection of oil autoxidation, serving as a quality control tool for potential acrolein precursor emissions, thereby enhancing food safety in the industry.

Real-time monitoring of vegetable oils photo-oxidation kinetics using differential photocalorimetry.

This study introduced differential photocalorimetry (DPC) as a method for real-time monitoring of the photo-oxidation kinetics of vegetable oils. DPC measures the heat flow generated during the oxidation of oils upon light exposure. Experiments conducted with stripped linseed oil (SLSO), an oil depleted from its natural antioxidants, showed no induction time (τ). Conversely, spiking SLSO with increasing concentrations of trans-ferulic acid resulted in an induction time (τ) proportional to the antioxidant concentration (R2 = 0.99). A comparative study among different vegetable oils revealed that rice bran oil exhibited the highest resistant to photo-oxidation, followed by corn, soybean, and sunflower oils. The results are discussed in terms of sample oxidizability and antioxidant efficiency (A.E.), and validated through high-performance liquid chromatography with diode array detection (HPLC-DAD). Furthermore, the measured heat flow enabled the determination of the rates of inhibited (Rinh) and uninhibited (Runi) periods, as well as the rate constant of propagation (kp) and inhibition (kinh) reactions.

Structuring vegetable oils through enzymatic glycerolysis for water-in-oil emulsions.

Enzymatic glycerolysis is a biotechnological process for structuring vegetable oils. This study investigates the kinetics of glycerolysis of peanut oil and explores the potential of the resulting structured oil to enhance the physical stability of water-in-oil emulsions. Using a 1:1 glycerol-to-oil molar ratio and 4 % lipase B from Candida antarctica as a catalyst, the reaction was conducted at 65 °C with stirring at 400 rpm. Acylglyceride fractions changes were quantified through NMR and DSC. Fat crystal formation was observed using scanning electron microscopy. The results revealed a first-order decay pattern, converting triglycerides into monoacylglycerides and diacylglycerides in less than 16 h. Subsequently, water-in-oil emulsions prepared with glycerolized oil showed augmented stability through multiple light scattering techniques and visual assessment. The structured oils effectively delayed phase separation, highlighting the potential of glycerolysis in developing vegetable oil-based emulsions with improved functional properties and reduced saturated fatty acid content.

Novel formulations for developing fresh hybrid cheese analogues utilizing fungal-fermented brewery side-stream flours.

This study investigated the development of hybrid cheese analogues (HCA) made with fermented brewery side-stream ingredients (spent yeast and malt rootlets) and dairy milk. Different percentages of side-stream flours (3.5%, 5%, and 7.5%) were mixed with pasteurized milk, and the developed HCA were evaluated for their biochemical and textural properties. The addition of a fermentation step improved nutrient availability and led to pH (range 4.79-5.60) and moisture content (range 45.86%-61.29%) similar to traditional animal-based fresh cheeses (control). The inclusion of side-stream flours led to coagulation, even without rennet addition. The higher the concentration of the flour used, the faster the coagulation time, suggesting synergistic effect between the enzymes of the rennet and the enzymes present in the fermented side-stream flours. Nevertheless, textural properties were inferior compared to the control. Selected HCA formulations with added 3.5% flour exhibited increased counts of enterococci and enterobacteria cell densities, ranging from 7.28 ± 0.03 to 7.72 ± 0.09 log CFU/g and 4.90 ± 0.16 to 5.41 ± 0.01 log CFU/g, respectively. Compared to the control sample, HCA formulations exhibited higher concentrations of organic acids, peptides, and free amino acids (FAAs). Lactic acid reached up to 23.78 ± 0.94 g/kg of dry matter (DM), while the peptide area reached up to 22918.50 ± 2370.93 mL⋅AU. Additionally, the total concentration of individual FAAs reached up to 2809.74 ± 104.85 mg/kg of DM, contrasted with the control, which resulted in lower concentrations (847.65 ± 0.02 mg/kg of DM). The overall findings suggested that despite challenges in microbiological quality and textural properties, HCA produced with the inclusion of up to 3.5% brewery side-stream flours could be a sustainable solution to produce nutritious dairy alternatives.

Establishing authenticity of hay milk: Detection of silage feeding through cyclopropane fatty acids analysis using 1H NMR spectroscopy.

Cyclopropane fatty acids (CPFAs) serve as indicators of silage feeding, verifying the authenticity of hay milk where silage feeding is forbidden. In this study, the authenticity of hay milk was determined by detecting CPFAs using proton nuclear magnetic resonance (1H NMR) spectroscopy. 245 milk samples were collected in South Tyrol (Italy), categorized as follows: 98 from grass silage-fed cows, 98 from maize silage-fed cows, and 49 authentic hay milk. The limit of detection of CPFAs was 12 µM, corresponding to 70 mg/kg of freeze-dried milk. The CPFAs were absent in all of the hay milk samples, verifying their authenticity. In contrast, 97 % of maize silage and 77 % of grass silage samples exhibited distinct CPFAs signals. These findings were further corroborated by gas chromatography-mass detector (GC-MS) analysis. The study highlights 1H NMR as a robust, and rapid technique for hay milk authentication, supporting alpine dairy production and increasing consumer trust in food authenticity.

Comparison of quantitative PCR and flow cytometry as cellular viability methods to study bacterial membrane permeabilization following supercritical CO2 treatment.

Foodborne illness due to bacterial pathogens is increasing worldwide as a consequence of the higher consumption of fresh and minimally processed food products, which are more easily cross-contaminated. The efficiency of food pasteurization methods is usually measured by c.f.u. plate counts, a method discriminating viable from dead cells on the basis of the ability of cells to replicate and form colonies on standard growth media, thus ignoring viable but not cultivable cells. Supercritical CO2 (SC-CO2) has recently emerged as one of the most promising fresh food pasteurization techniques, as an alternative to traditional, heat-based methods. In the present work, using three SC-CO2-treated foodborne bacteria (Listeria monocytogenes, Salmonella enterica and Escherichia coli) we tested and compared the performance of alternative viability test methods based on membrane permeability: propidium monoazide quantitative PCR (PMA-qPCR) and flow cytometry (FCM). Results were compared based on plate counts and fluorescent microscopy measurements, which showed that the former dramatically reduced the number of cultivable cells by more than 5 log units. Conversely, FCM provided a much more detailed picture of the process, as it directly quantifies the number of total cells and distinguishes among three categories, including intact, partially permeabilized and permeabilized cells. A comparison of both PMA-qPCR and FCM with plate count data indicated that only a fraction of intact cells maintained the ability to replicate in vitro. Following SC-CO2 treatment, FCM analysis revealed a markedly higher level of bacterial membrane permeabilization of L. monocytogenes with respect to E. coli and S. enterica. Furthermore, an intermediate permeabilization state in which the cellular surface was altered and biovolume increased up to 1.5-fold was observed in L. monocytogenes, but not in E. coli or S. enterica. FCM thus compared favourably with other methods and should be considered as an accurate analytical tool for applications in which monitoring bacterial viability status is of importance, such as microbiological risk assessment in the food chain or in the environment.

Apples and Apple By-Products: Antioxidant Properties and Food Applications.

In recent years, there has been a growing interest in utilizing natural antioxidants as alternatives to synthetic additives in food products. Apples and apple by-products have gained attention as a potential source of natural antioxidants due to their rich phenolic content. However, the extraction techniques applied for the recovery of phenolic compounds need to be chosen carefully. Studies show that ultrasound-assisted extraction is the most promising technique. High yields of phenolic compounds with antioxidant properties have been obtained by applying ultrasound on both apples and their by-products. Promising results have also been reported for green technologies such as supercritical fluid extraction, especially when a co-solvent is used. Once extracted, recent studies also indicate the feasibility of using these compounds in food products and packaging materials. The present review aims to provide a comprehensive overview of the antioxidant properties of apples and apple by-products, their extraction techniques, and potential applications in food products because of their antioxidant or nutritional properties. The findings reported here highlight the proper utilization of apples and their by-products in food to reduce the detrimental effect on the environment and provide a positive impact on the economy.

Supercritical Fluid Extraction of Oils from Cactus Opuntia ficus-indica L. and Opuntia dillenii Seeds.

This study aimed to assess the capability of supercritical fluid extraction (SFE) as an alternative and green technique compared to Soxhlet extraction for the production of oils from Opuntia ficus-indica (OFI) seeds originating from Yemen and Italy and Opuntia dillenii (OD) seeds from Yemen. The following parameters were used for SFE extraction: a pressure of 300 bar, a CO2 flow rate of 1 L/h, and temperatures of 40 and 60 °C. The chemical composition, including the fatty acids and tocopherols (vitamin E) of the oils, was determined using chromatographic methods. The highest yield was achieved with Soxhlet extraction. The oils obtained with the different extraction procedures were all characterized by a high level of unsaturated fatty acids. Linoleic acid (≤62% in all samples) was the most abundant one, followed by oleic and vaccenic acid. Thirty triacylglycerols (TAGs) were identified in both OFI and OD seed oils, with trilinolein being the most abundant (29-35%). Vanillin, 4-hydroxybenzaldehyde, vanillic acid, and hydroxytyrosol were phenols detected in both OFI and OD oils. The highest γ-tocopherol content (177 ± 0.23 mg/100 g) was obtained through the SFE of OFI seeds from Yemen. Overall, the results highlighted the potential of SFE as green technology to obtain oils suitable for functional food and nutraceutical products.

Oxidizability of Oils Recovered from Olive Seeds by Isothermal Calorimetry.

This work aims to apply isothermal calorimetry for the determination of the oxidative stability of bulk oils by deriving kinetic and thermodynamic parameters. The method consists of measuring the heat flow produced during the oxidation of the oils in the presence of oxygen. To this purpose, an oil was recovered from olive seeds, the solid waste derived from the transformation of olives, by using two different technologies: supercritical carbon dioxide and mechanical press. The oxidative stability of both extracted oils was then compared with commercial sunflower, soybean, corn, and rice oils. The kinetic and thermodynamic parameters, obtained from the analysis of isothermal calorimetry traces at 60 °C, allowed the calculation of the oxidizability index obtaining the following ranking: olive seeds by supercritical carbon dioxide (3.55 ± 0.4 × 10−3 (s/M)0.5) > sunflower (3.42 ± 0.8 × 10−3 (s/M)0.5) > olive seeds by mechanical press (3.07 ± 0.3 × 10−3 (s/M)0.5) > soybean (2.44 ± 0.6 × 10−3 (s/M)0.5) > corn (1.11 ± 0.4 × 10−3 (s/M)0.5) > rice oils (0.98 ± 0.4 × 10−3 (s/M)0.5). The results were then supported with the analysis of total phenolic content, antioxidant activity, fatty acid profile, and peroxide values. Overall, the findings of the present study support the use of isothermal calorimetry as a direct and non-invasive technique for determining the oxidizability of bulk oils.

Multiple Light Scattering Measurements for Online Monitoring of Milk Fermentation.

The present paper investigates the use of multiple light scattering for the monitoring of milk fermentation. The experiments were performed on milk fermented with different starter concentrations (0.05% to 4.5% (w/w) at temperatures from 36 to 44 °C and in the presence of antibiotics at concentrations up to 100 µg/kg. The fermentation was monitored continuously by using a multiple light scattering technique and simultaneously by a pH meter, a rheometer and a texture analyzer. The backscattering signal recorded by multiple light scattering measurements was correlated with the changes in pH, rheological parameters and firmness of the samples along the fermentation. A gelation time of 120 min was obtained when the highest concentration of starter (4.5%, w/w) and incubation temperature of 44 °C were used. These results were confirmed by the pH, rheological and texture monitoring. The analysis of backscattering spectra allowed the detection of the effect of antibiotic on the gel formation even at low concentrations (1.3 µg/kg). Overall, the results highlighted the advantages of using a multiple light scattering technique as quality control tool for online monitoring of milk fermentation.

The Effect of Microfluidization Pressure and Tocopherol Content on the Retention of Vitamin A in Oil-In-Water Emulsions.

This work investigates the oxidative stability of vitamin A encapsulated in oil-in-water emulsions, which were prepared by using a microfluidizer. All emulsions were prepared with a fixed content of vitamin A (525 µM), corn oil (10%), water (90%), and whey protein (2%), but varying two main factors: the microfluidizer pressure (10, 50, 100, 200 MPa) and the amount of α-tocopherol (0, 0.25, 0.50, 1.00 mg/g). The content of vitamin A before and after the microfluidization process, and during the subsequent five weeks of storage at 40 °C were determined by HPLC-DAD. The results of the analysis of variance performed either on the data obtained before and after the microfluidization process or during the storage showed that the highest stability of vitamin A was obtained with the highest content of α-tocopherol and with an applied pressure between 100 and 200 MPa. The highest stability was explained by the smaller particle size of the resulting oil droplets. However, high pressures (200 MPa) showed a negative effect on vitamin A retention. These results could be useful for future formulations of retinoids.

Extraction of Essential Oils from Medicinal Plants and their Utilization as Food Antioxidants.

BACKGROUND: The use of essential oils is receiving increasing attention worldwide, as these oils are good sources of several bioactive compounds. Nowadays essential oils are preferred over synthetic preservatives thanks to their antioxidant and antimicrobial properties. Several studies highlight the beneficial effect of essential oils extracted from medicinal plants to cure human diseases such as hypertension, diabetes, or obesity. However, to preserve their bioactivity, the use of appropriate extraction technologies is required. METHODS: The present review aims to describe the studies published so far on the essential oils focusing on their sources and chemical composition, the technologies used for their recovery and their application as antioxidants in food products. RESULTS: The review has been structured in three parts. In the first part, the main compounds present in essential oils extracted from medicinal plants have been listed and described. In the second part, the most important technologies used for extraction and distillation, have been presented. In detail, conventional methods have been described and compared with innovative and green technologies. Finally, in the last part, the studies related to the application of essential oils as antioxidants in food products have been reviewed and the main findings discussed in detail. CONCLUSION: In summary, an overview of the aforementioned subjects is presented by discussing the results of the most recent published studies.