Research

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18 pages, 1302 KiB

Open AccessArticle

Coffee Silver Skin: Chemical Characterization with Special Consideration of Dietary Fiber and Heat-Induced Contaminants

by Vera Gottstein, Mara Bernhardt, Elena Dilger, Judith Keller, Carmen M. Breitling-Utzmann, Steffen Schwarz, Thomas Kuballa, Dirk W. Lachenmeier and Mirko Bunzel

Foods 2021, 10(8), 1705; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10081705 - 23 Jul 2021

Cited by 23 | Viewed by 6048

Abstract

Coffee silver skin is produced in large amounts as a by-product during the coffee roasting process. In this study, coffee silver skin of the species Coffea arabica L. and Coffea canephora Pierre ex A. Froehner as well as silver skin pellets produced in [...] Read more.

Coffee silver skin is produced in large amounts as a by-product during the coffee roasting process. In this study, coffee silver skin of the species Coffea arabica L. and Coffea canephora Pierre ex A. Froehner as well as silver skin pellets produced in the coffee industry were characterized with respect to both nutritional value and potential heat-induced contaminants. Enzymatic-gravimetric/chromatographic determination of the dietary fiber content showed values ranging from 59 to 67 g/100 g with a comparably high portion of soluble fiber, whereas low molecular weight soluble fiber was not detected. Compositional and methylation analysis indicated the presence of cellulose and xylans in the insoluble dietary fiber fraction, whereas pectic polysaccharides dominate the soluble dietary fiber fraction. The protein content as determined by the Kjeldahl method was in the range of 18 to 22 g/100 g, and all essential amino acids were present in coffee silver skin; whereas fat contents were low, high ash contents were determined. Elemental analysis by inductively coupled plasma mass spectrometry (ICP-MS) showed the presence of macroelements in large amounts, whereas toxic mineral elements were only detected in trace amounts or being absent. Acrylamide was quantified with levels of 24–161 µg/kg. Although 5-hydroxymethylfurfural was detected, its concentration was below the limit of determination. Furfuryl alcohol was not detected. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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17 pages, 25516 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Oil Content and Oil Addition Point on the Extrusion Processing of Wheat Gluten-Based Meat Analogues

by Christina Kendler, Arvid Duchardt, Heike P. Karbstein and M. Azad Emin

Foods 2021, 10(4), 697; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10040697 - 25 Mar 2021

Cited by 42 | Viewed by 5368

Abstract

High-moisture extrusion is a common process to impart an anisotropic, meat-like structure to plant proteins, such as wheat gluten. The addition of oil during the process promises to enhance the sensory properties of the meat analogs. In this study, the influence of oil [...] Read more.

High-moisture extrusion is a common process to impart an anisotropic, meat-like structure to plant proteins, such as wheat gluten. The addition of oil during the process promises to enhance the sensory properties of the meat analogs. In this study, the influence of oil on extrusion-relevant parameters as well as the structure-related characteristics of extruded wheat gluten was investigated. Oil was added directly to the extruder at different contents (0, 2, 4, 6%) and addition points (front/end of the extruder barrel). Process conditions, complex viscosity, Young’s modulus and oil phase morphology were determined as a function of oil content and oil addition point. With increasing oil content, material temperature, die pressure, and complex viscosity decreased. The addition of oil at the end of the extruder barrel reduced this effect compared to the addition of oil in the front part of the extruder. It was observed that the extrudate’s tensile strength is a function of material temperature, resulting in an increase in tensile strength with increasing material temperature. The oil was dispersed in the gluten matrix as small droplets with irregular shape. As the oil content increased, the size of the oil droplets increased, while the addition of oil at the end of the extruder resulted in a decrease in droplet size. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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17 pages, 6256 KiB

Open AccessArticle

Concentrating Model Solutions and Fruit Juices Using CO₂ Hydrate Technology and Its Quantitative Effect on Phenols, Carotenoids, Vitamin C and Betanin

by Alexander Rudolph, Amna El-Mohamad, Christopher McHardy and Cornelia Rauh

Foods 2021, 10(3), 626; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10030626 - 16 Mar 2021

Cited by 12 | Viewed by 2817

Abstract

Fruits have an important economic impact in the context of plant-based food production. The consumption of fruit juices, mostly produced from concentrates, is particularly noteworthy. Conventional concentration methods do not always enable a sustainable and gentle concentration. The innovative gas hydrate technology addresses [...] Read more.

Fruits have an important economic impact in the context of plant-based food production. The consumption of fruit juices, mostly produced from concentrates, is particularly noteworthy. Conventional concentration methods do not always enable a sustainable and gentle concentration. The innovative gas hydrate technology addresses this point with its energy-saving, gentle character, and high concentration potential. In this study, the concentration of fruit juices and model solutions using CO

_{2}

hydrate technology was investigated. To find a suitable operating point for hydrate formation in the used bubble column, the hydrate formation in a water–sucrose model solution was evaluated at different pressure and temperature combinations (1, 3, 5 °C and 32.5, 37.5, 40 bar). The degrees of concentration indicate that the bubble column reactor operates best at 37.5 bar and 3 °C. To investigate the gentle processing character of the hydrate technology, its quantitative effects on vitamin C, betanin, polyphenols, and carotenoids were analyzed in the produced concentrates and hydrates via HPLC and UV/VIS spectrophotometry. The results for fruit juices and model solutions imply that all examined substances are accumulated in the concentrate, while only small amounts remain in the hydrate. These amounts can be related to an inefficient separation process. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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17 pages, 1548 KiB

Open AccessArticle

Impact of Rapeseed Press Cake on the Rheological Properties and Expansion Dynamics of Extruded Maize Starch

by Anna Martin, Raffael Osen, Heike Petra Karbstein and M. Azad Emin

Foods 2021, 10(3), 616; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10030616 - 14 Mar 2021

Cited by 3 | Viewed by 2482

Abstract

Rapeseed press cake (RPC), an oil pressing side product rich in protein and fiber, can be combined with starch and valorized into directly expanded products using extrusion technology. The mechanism of starch expansion has been studied in detail, but the impact of RPC [...] Read more.

Rapeseed press cake (RPC), an oil pressing side product rich in protein and fiber, can be combined with starch and valorized into directly expanded products using extrusion technology. The mechanism of starch expansion has been studied in detail, but the impact of RPC on expansion behavior is poorly understood. However, it can be linked to rheological and physicochemical properties and is a key product quality parameter. Blends with different amounts of RPC (0, 10, 40 g/100 g) were extruded at different barrel temperatures (100, 120, 140 °C) and moisture contents (24 or 29 g/100 g). The initial, intermediate and final sectional, longitudinal and volumetric expansion indices (SEI, LEI, VEI) were monitored directly, 10 s and 24 h after die exit to measure extrudate growth and shrinkage. The viscous and elastic properties of the extruded blends were investigated in a closed cavity rheometer. Starch and blends with 10 g/100 g RPC achieved a high initial SEI followed by significant short-term shrinkage. Blends containing 40 g/100 g RPC did not show any initial expansion. With increasing RPC content, the intermediate SEI decreased, but all samples reached a similar final SEI due to time-dependent swelling of the RPC blends. With increasing RPC content, the elasticity of the starch-based extruded samples significantly increased. Our study shows that comprehensive control and understanding of expansion mechanisms can be achieved only by investigating all stages of extrudate growth and shrinkage. We also found that the closed cavity rheometer is a powerful tool to correlate the rheological properties and expansion mechanisms of biopolymers. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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21 pages, 40720 KiB

Open AccessArticle

Functionalization of Enzymatically Treated Apple Pomace from Juice Production by Extrusion Processing

by Vera Schmid, Antje Trabert, Judith (Schäfer) Keller, Mirko Bunzel, Heike P. Karbstein and M. Azad Emin

Foods 2021, 10(3), 485; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10030485 - 24 Feb 2021

Cited by 6 | Viewed by 2597

Abstract

Food by-products can be used as natural and sustainable food ingredients. However, a modification is needed to improve the technofunctional properties according to the specific needs of designated applications. A lab-scale twin-screw extruder was used to process enzymatically treated apple pomace from commercial [...] Read more.

Food by-products can be used as natural and sustainable food ingredients. However, a modification is needed to improve the technofunctional properties according to the specific needs of designated applications. A lab-scale twin-screw extruder was used to process enzymatically treated apple pomace from commercial fruit juice production. To vary the range of the thermomechanical treatment, various screw speeds (200, 600, 1000 min⁻¹), and screw configurations were applied to the raw material. Detailed chemical and functional analyses were performed to develop a comprehensive understanding of the impact of the extrusion processing on apple pomace composition and technofunctional properties as well as structures of individual polymers. Extrusion at moderate thermomechanical conditions increased the water absorption, swelling, and viscosity of the material. An increase in thermomechanical stress resulted in a higher water solubility index, but negatively affected the water absorption index, viscosity, and swelling. Scanning electron microscopy showed an extrusion-processing-related disruption of the cell wall. Dietary fiber analysis revealed an increase of soluble dietary fiber from 12.6 to 17.2 g/100 g dry matter at maximum thermo-mechanical treatment. Dietary fiber polysaccharide analysis demonstrated compositional changes, mainly in the insoluble dietary fiber fraction. In short, pectin polysaccharides seem to be susceptible to thermo-mechanical stress, especially arabinans as neutral side chains of rhamnogalacturonan I. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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17 pages, 6132 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

High Moisture Extrusion of Soy Protein: Investigations on the Formation of Anisotropic Product Structure

by Patrick Wittek, Nicole Zeiler, Heike P. Karbstein and M. Azad Emin

Foods 2021, 10(1), 102; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10010102 - 06 Jan 2021

Cited by 67 | Viewed by 7425

Abstract

The high moisture extrusion of plant proteins is well suited for the production of protein-rich products that imitate meat in their structure and texture. The desired anisotropic product structure of these meat analogues is achieved by extrusion at high moisture content (>40%) and [...] Read more.

The high moisture extrusion of plant proteins is well suited for the production of protein-rich products that imitate meat in their structure and texture. The desired anisotropic product structure of these meat analogues is achieved by extrusion at high moisture content (>40%) and elevated temperatures (>100 °C); a cooling die prevents expansion of the matrix and facilitates the formation of the anisotropic structure. Although there are many studies focusing on this process, the mechanisms behind the structure formation still remain largely unknown. Ongoing discussions are based on two very different hypotheses: structure formation due to alignment and stabilization of proteins at the molecular level vs. structure formation due to morphology development in multiphase systems. The aim of this paper is, therefore, to investigate the mechanism responsible for the formation of anisotropic structures during the high moisture extrusion of plant proteins. A model protein, soy protein isolate, is extruded at high moisture content and the changes in protein–protein interactions and microstructure are investigated. Anisotropic structures are achieved under the given conditions and are influenced by the material temperature (between 124 and 135 °C). Extrusion processing has a negligible effect on protein–protein interactions, suggesting that an alignment of protein molecules is not required for the structure formation. Instead, the extrudates show a distinct multiphase system. This system consists of a water-rich, dispersed phase surrounded by a water-poor, i.e., protein-rich, continuous phase. These findings could be helpful in the future process and product design of novel plant-based meat analogues. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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Review

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29 pages, 878 KiB

Open AccessEditor’s ChoiceReview

Functionality of Ingredients and Additives in Plant-Based Meat Analogues

by Konstantina Kyriakopoulou, Julia K. Keppler and Atze Jan van der Goot

Foods 2021, 10(3), 600; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10030600 - 12 Mar 2021

Cited by 224 | Viewed by 40248

Abstract

Meat analogue research and development focuses on the production of sustainable products that recreate conventional meat in its physical sensations (texture, appearance, taste, etc.) and nutritional aspects. Minced products, like burger patties and nuggets, muscle-type products, like chicken or steak-like cuts, and emulsion [...] Read more.

Meat analogue research and development focuses on the production of sustainable products that recreate conventional meat in its physical sensations (texture, appearance, taste, etc.) and nutritional aspects. Minced products, like burger patties and nuggets, muscle-type products, like chicken or steak-like cuts, and emulsion products, like Frankfurter and Mortadella type sausages, are the major categories of meat analogues. In this review, we discuss key ingredients for the production of these novel products, with special focus on protein sources, and underline the importance of ingredient functionality. Our observation is that structuring processes are optimized based on ingredients that were not originally designed for meat analogues applications. Therefore, mixing and blending different plant materials to obtain superior functionality is for now the common practice. We observed though that an alternative approach towards the use of ingredients such as flours, is gaining more interest. The emphasis, in this case, is on functionality towards use in meat analogues, rather than classical functionality such as purity and solubility. Another trend is the exploration of novel protein sources such as seaweed, algae and proteins produced via fermentation (cellular agriculture). Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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29 pages, 2423 KiB

Open AccessEditor’s ChoiceReview

Methods for Testing the Quality Attributes of Plant-Based Foods: Meat- and Processed-Meat Analogs

by David Julian McClements, Jochen Weiss, Amanda J. Kinchla, Alissa A. Nolden and Lutz Grossmann

Foods 2021, 10(2), 260; https://0-doi-org.brum.beds.ac.uk/10.3390/foods10020260 - 27 Jan 2021

Cited by 57 | Viewed by 15209

Abstract

The modern food system is seeing a change in consumption patterns provoked by several drivers—including ethical, health, and environmental concerns—that are increasing the sales of meat analog foods. This change is accompanied by increased research and development activities in the area of plant-based [...] Read more.

The modern food system is seeing a change in consumption patterns provoked by several drivers—including ethical, health, and environmental concerns—that are increasing the sales of meat analog foods. This change is accompanied by increased research and development activities in the area of plant-based meats. The aim of the present review is to describe methods that are being employed by scientists to analyze and characterize the properties of meat alternatives and to propose standardized methods that could be utilized in the future. In particular, methods to determine the proximate composition, microstructure, appearance, textural properties, water-holding properties, cooking resilience, and sensory attributes, of plant-based meat are given. The principles behind these methods are presented, their utility is critically assessed, and practical examples will be discussed. This article will help to guide further studies and to choose appropriate methods to assess raw materials, processes, products, and consumption behavior of meat analogs. Full article

(This article belongs to the Special Issue Latest Advances in Plant-Based Food Processing to Improve the Sustainability in the Food Supply Chain)

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