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To tackle the issue of preserving natural resources and reducing pollution, the circular economy has been identified as a lever to ensure food security for 9 billion people by 2050. In the brewing sector, the annual production of wet spent grain represents 8 million tons in Europe and 40 million tons worldwide. This deposit represents a major opportunity in the current context of sustainable food transition, as it is an important source of protein, fiber, and other nutrients for human nutrition. Several initiatives regarding the valorization of brewer’s spent grain are emerging in human food, but studies to assess the environmental impact of different scenarios are still missing. Indeed, numerous separate or combined treatments could be involved in spent grain stabilization. The evaluation of the separate pathways identified could help to clarify the choices made by future economic actors willing to start a new activity or any researcher or manager willing to participate in a project to exploit the spent grain in food. The objective of this article is to conduct a comparative study of the environmental performance of different brewing grain stabilization engineering strategies among dehydration, separation, lactofermentation, freeze-drying, refrigeration, freezing, methanation, composting, and use for animal feed. These processes or their combinations for spent grain upcycling in human consumption will be examined by life cycle assessment, an ISO-standardized accounting methodology for quantifying the environmental impacts of a product. To our knowledge, this study is the first to include an environmental impact assessment of the spent grain stabilization pathways. The influence of the introduction of a new step in the life cycle of the upcycled spent grain on the environmental load of the product is highly significant. The results highlight the importance of strategic choices of stabilization processes and process coupling, a major step for spent grain reuse in human nutrition. This study provides trends and recommendations on parameters to be compared for technical and organizational strategies for byproduct valorization in food in the context of the circular economy.

In this study, benchmarking of methods used for assessing freeze damage in potatoes was carried out. Initially, the samples were frozen by subjecting them to three different temperatures (i.e. at – 18 °C, − 30 °C, and at − 74 °C). Then, different analytical techniques comprising of focused methods (i.e. cryo-Scanning elctron microscopy-cryo-SEM, confocal laser scanning microscopy-CLSM) and global methods (i.e. texture analysis, low field nuclear magnetic resonance (NMR), exudate loss and colour change) were used to assess the impact of the freezing treatment from the different point of view addressed by each method. As a result, each of these methods were able to distinguish significantly fresh samples from the frozen-thawed samples. Focused methods like cryo-SEM and CLSM methods could differentiate the impact of all three different protocols. Meanwhile, texture analysis (including conventional method and novel method based on a touchless laser puff firmness tester), NMR and exudate loss could only determine the quality difference between − 18 °C and − 74 °C freezing conditions. Colour analysis was found as an inappropriate parameter for comparing the three freezing protocols. Among all analytical techniques, cryo-SEM provides the most authentic information about the product as the analysis is performed in frozen state, while for other techniques the product is thawed prior to analysis.

Entomophagy has been part of human diets for a long time in a significant part of the world, but insects are considered to be a novel food everywhere else. It would appear to be a strategic alternative in the future of human diet to face the challenge of ensuring food security for a growing world population, using more environmentally sustainable production systems than those required for the rearing of other animals. Tenebrio molitor, called yellow mealworm, is one of the most interesting insect species in view of mass rearing, and can be processed into a powder that ensures a long shelf life for its use in many potential products. When considering insects as food or feed, it is necessary to guarantee their safety. Therefore, manufacturers must implement a Hazard Analysis Critical Control plan (HACCP), to limit risks for consumers’ health. The aim of this case study was to develop a HACCP plan for Tenebrio molitor larvae powders for food in a risk-based approach to support their implementation in industry. Specific purposes were to identify related significant biological hazards and to assess the efficiency of different manufacturing process steps when used as Critical Control Points. Then, combinations of four different processes with four potential uses of powders by consumers in burger, protein shake, baby porridge, and biscuits were analyzed with regard to their safety.

The effect of baking temperature (vault and hearth) and steam injection on bread characteristics and acrylamide content was investigated using a central composite design. Breads were baked in a stone oven (1 m² internal baking surface). Response variables measured were specific volume, crumb porosity, crust to crumb ratio, crumb hardness, median gas cell size, crust coloration and acrylamide concentration. The specific volume, crumb porosity, crumb hardness and median gas cell diameter were mainly affected by the stone temperature and steam injection level. Highest specific volume (5 mL.g-1) and crumb porosity (86%) were obtained at highest stone temperature (230°C) and steam level (300 mL). At the same baking conditions and highest vault temperature (230°C), a minimal crumb hardness and median gas cell diameter were attained, as well. A negative linear correlation between the specific volume (crumb porosity) of the bread and its textural properties (crumb hardness and median gas cell diameter) was found. Vault temperature mainly influenced crust characteristics. Thus, increased vault temperature increased the crust coloration and crust crumb ratio. Vault temperature and steaming were found to have greatest effect on acrylamide concentration. As they were increased the acrylamide concentration increased, too. Additionally, a strong correlation between crust color and acrylamide concentration was observed. As the crust total color difference increased up to 20-25, acrylamide concentration increased linearly. However, for a higher level of crust coloration the acrylamide concentration was found to leveling out or even to decrease slowly.

International audience; Food freezing is a complex process, involving heat transfer and a series of physical and chemical changes which may profoundly affect the product quality. Several novel freezing methods have been developed in recent times taking into account the energy saving and/or quality preservation to a greater extent upon thawing. Electro-freezing technique, especially electric field assisted freezing is gaining momentum among them; it offers less energy intensive freezing conditions (higher set point ambient temperature, lower air velocity), and allows better quality retention. In the present short review article, a focused overview of the main findings and the latest studies regarding the applications of electro-freezing in food is given.

Global sustainability indicators, particularly in human health, are necessary to describe agrifood products footprint. Nitrosamines are toxic molecules that are often encountered in cured and processed meats. As they are frequently consumed, meat-based products need to be assessed to evaluate their potential impact on human health. This article provides a methodological framework based on life cycle assessment for comparing meat product processing scenarios. The respective contributions of each step of the product life cycle are extended with a new human health indicator, nitrosamine toxicity, which has not been previously included in life cycle assessment (LCA) studies and tools (software and databases). This inclusion allows for the comparison of conventional versus innovative processes. Nitrosamines toxicity was estimated to be 2.20x10&minus, 6 disability-adjusted life years (DALY) for 1 kg of consumed conventional cooked ham while 4.54x10&minus, 7 DALY for 1 kg of consumed innovative cooked ham. The potential carcinogenic and noncarcinogenic effects of nitrosamines from meat products on human health are taken into account. Human health indicators are an important step forward in the comprehensive application of LCA methodology to improve the global sustainability of food systems.

The effects of xanthan gum on the structural modifications of myofibrillar proteins (0.3 M NaCl, pH 6) induced by high pressure (200, 400, and 600 MPa, 6 min) were investigated. The changes in the secondary and tertiary structures of myofibrillar proteins were analyzed by circular dichroism. The protein denaturation was also evaluated by differential scanning calorimetry. Likewise, the protein surface hydrophobicity and the solubility of myofibrillar proteins were measured. High pressure (600 MPa) induced the loss of α-helix structures and an increase of β-sheet structures. However, the presence of xanthan gum hindered the former mechanism of protein denaturation by high pressure. In fact, changes in the secondary (600 MPa) and the tertiary structure fingerprint of high-pressure-treated myofibrillar proteins (400 to 600 MPa) were observed in the presence of xanthan gum. These modifications were confirmed by the thermal analysis, the thermal transitions of high-pressure (400 to 600 MPa)-treated myofibrillar proteins were modified in systems containing xanthan gum. As consequence, the high-pressure-treated myofibrillar proteins with xanthan gum showed increased solubility from 400 MPa, in contrast to high-pressure treatment (600 MPa) without xanthan gum. Moreover, the surface hydrophobicity of high-pressure-treated myofibrillar proteins was enhanced in the presence of xanthan gum. These effects could be due to the unfolding of myofibrillar proteins at high-pressure levels, which exposed sites that most likely interacted with the anionic polysaccharide. This study suggests that the role of food additives could be considered for the development of meat products produced by high-pressure processing.

To investigate the impact of baking conditions on staling kinetics and mechanical properties, pan breads were baked at 180 °C/34 min and 220 °C/28.6 min using a ventilated oven and metallic moulds. After baking, bread slices were stored with and without crust at 15 °C in hermetic boxes for 9 days. This investigation provides a textural and physical analysis by examining the Young's modulus, crumb density and crust/crumb ratio during storage. In order to understand the relationship between firmness and moisture content, a moisture profile and a Young's modulus profile were determined during the storage of bread. To fit the staling, a first order model was used. It was found that the kinetics were faster for samples baked with a fast heating rate than for those baked with a slow heating rate. Moreover, the staling rate of bread stored with crust was faster than for bread without crust and the outer crust area staled more rapidly than the centre of the bread slice. These results suggest that the firming of the crumb is related to moisture distribution between the crumb and crust and to the impact of local baking conditions on local firmness.

The effect of two baking conditions 240 °C and 220 °C (corresponding to heating rates 7.39 and 6.11 °C/min respectively) on the cellular structure of bread was investigated using X-ray microtomography. A comparison between helium pycnometry and X-ray microtomography was carried out and confirmed the quality of analysis in 3-D. Porosity profiles were determined in the interface crust/crumb and showed higher porosity and lower density of the upper crust when increasing heating rate and baking with steaming. The porosity profile of the whole slice bread showed differences between breads baked at 220 °C and 240 °C; that can be explained by the non uniformity in local expansion during baking resulting in different areas of variable density. Higher density was found in the bottom of the slice due to compression forces during baking. However, the upper zone of the slice was more porous, in relation with the expansion. These differences influence the texture and led to different kinetics of staling. Results of tortuosity confirm that the relative path length is shorter along the height related to the expansion of the bread during baking. Additionally, the relative path length through the pores is shorter when baking at 240 °C than when baking at 220 °C, in relation with porosity.

In order to develop a mathematical model to simulate mass transfer occurring between the crumb and the crust during bread staling, water vapor sorption properties, i.e., moisture diffusivity, WVP and sorption of bread crumb and crust were investigated at 15 °C. Two types of bread baked with two heating rates (7.39 °C/min and 6.32 °C/min) were considered. Sorption and desorption isotherms were determined using Dynamic Vapor Sorption (DVS) and FF and GAB models were applied in the range of 0–0.95 aw, to fit isotherm curves. Diffusivity was determined from sorption isotherms by using Fick's law and WVP was measured by two methods (gravimetric and from sorption data). Results exhibited maximum values of Deff in the range of 0.1 and 0.14 g/g d.b. moisture contents. They varied between 0.88 × 10− 10 and 0.92 × 10− 10 m2/s for the crust and between 2.24 × 10− 10 and 2.64 × 10− 10 m2/s for the crumb, baked respectively at 220 °C and 240 °C. Results of WVP showed that the crust baked at 240 °C was significantly more permeable than the crust baked at 220 °C. This fact was attributed to the difference in porosity and the molecular structure due to heating effects. Also, the presence of steam in the oven atmosphere enhanced the development of higher porosity in the crust, leading to different structures and properties. Moreover, SEM images showed that starch granules were intact and less swelled in the upper crust when baking at 240 °C, resulting in higher WVP.

Enzymes such as α-amylase are extensively used to retard the staling process. Enzymes are acting both during fermentation and during baking. The objective of this work was to determine the relative action of α-amylase during fermentation and during baking. The impact of the baking conditions (time, temperature) was also considered. To attain this aim, a degassed bread crumb was baked in a miniaturized system using two programs of baking: heating rates 10.27 and 6.88 °C/min corresponding to 180 and 220 °C baking temperatures, respectively. Mechanical and thermodynamic properties of the degassed crumb were assessed during aging of bread by determining the Young’s modulus E, the amount of freezable water, and the melting enthalpy of retrograded amylopectin. A first-order kinetic model was used to determine the different parameters of staling kinetics. Results showed that the hardening of crumb increased during storage. The kinetics were faster for samples baked with fast heating rate than for those baked with slow heating rates. The use of enzymes decreased the Young’s modulus but did not have any effect on the staling rate. Calorimetric analysis of the starch retrogradation showed a reduction of the amount of freezable water during storage with an increase of retrograded amylopectin. A comparison between mechanical properties of conventional crumb and of the degassed dough confirmed that experimental data fitted correctly the Gibson and Ashby’s model.

The effect of the amount of steam injection on selected bread characteristics were investigated using a deck oven (1 m 2 internal surface). Baking was done at 200 °C for 20 min with steaming of 100, 200, 300, 400 and 500 ml. The temperature at center of the bread and the CO 2 concentration in the oven have been measured during baking. Specific volume, moisture loss and crust crumb ratio were measured after baking. The heating rate between 35 and 55 °C was considered to compare the steaming conditions. For low steaming (100 and 200 ml), the heating rate was significantly higher ( p 2 released during baking was higher for the highest amount of steaming; however, this result was not statistically different except between 100 and 500 ml. This could be attributed to a slower heating rate which in turns favors the secondary production of CO 2 during baking until thermal inactivation of CO 2 .

The main objective of the study was to assess the influence of moisture content on short infrared absorptivity of bread dough. Weight loss, surface temperature and short to medium infrared absorptivity of dough were measured in a series of radiant heating experiments. A strong positive correlation between surface temperature and total heat flux absorbed by the dough samples was observed. The variation of infrared absorptivity of the dough is explained with the state of the water in the samples – vapor or liquid.

This article presents some results on the energy demand in conventional bread baking and in the processing of frozen part baked breads, resulting from the “EU-FRESHBAKE” European project (FP6). Bread baking is one of the most energy demanding processes (around 4 MJ/kg), compared with other thermal processes such as canning. However, there is a large variability of data in the literature. For partial baking, bread has to be baked twice. It may also be frozen after part baking, which will increase the total energy demand. Results obtained with equipment used by craft bakeries are presented. Conventional and frozen part baked processes are compared. The effect of occupation ratio on the overall energy demand is also assessed. It was observed that 15–20% of the total energy is used for heating up the dough and 10–20% for crust drying. Pre-heating of the oven represents another significant energy demand. The energy demand for freezing is comparable to that for baking. An Energy Efficiency Index is used to assess the ratio of energy effectively transferred to the dough during baking. Part baked frozen technology demands about 2.2 times as much energy as conventional bread making process.

This paper presents a study on the impact of baking conditions on crumb staling. Breads were baked at 220 °C, 200 °C and 180 °C corresponding to 6, 8 and 10 min to rise the temperature to 98 °C in the crumb (heating rates 13, 9.8 and 7.8 °C/min respectively with an initial temperature of 20 °C). A new protocol has been developed, consisting in baking a slab of degassed dough in a miniaturized oven to mimic the baking conditions of conventional bread making. Texture tests were done during staling on degassed crumb and on conventional crumb. Calorimetry tests showed that during storage, amylopectin recrystallisation occurred before crumb stiffening. A first order kinetics model was used to fit the evolution of the crumb texture (Young's modulus) and of the recrystallisation of amylopectin. The results showed that the hardening of the crumb during staling occurred after retrogradation of amylopectin. In addition, the staling rate was faster for faster baking kinetics. A mechanical model showed that the relative Young modulus is proportional to the square of the relative density of the crumb.

The thermal conductivity of food is usually measured in isothermal conditions with a line-heat source probe. The thermal conductivity of bread during the baking phase is function of temperature and is an important parameter to assess. This work aims at (i) developing a measurement method of thermal conductivity in pseudo-non-isothermal conditions, usable during the part baked bread thawing–baking phase, and (ii) establishing models to predict the change of the thermal conductivity as function of the temperature. The line-heat source probe method has been used, the probe temperature being corrected by subtracting the temperature increase due to the baking. Values obtained in pseudo-non-isothermal conditions during the thawing–baking phase are similar to these ones obtained in isothermal conditions. A parallel model has been successfully used to fit the experimental values of the thermal conductivity of bread during the baking phase.

The effects of xanthan gum on the structural modifications of myofibrillar proteins (0.3 M NaCl, pH 6) induced by high pressure (200, 400, and 600 MPa, 6 min) were investigated. The changes in the secondary and tertiary structures of myofibrillar proteins were analyzed by circular dichroism. The protein denaturation was also evaluated by differential scanning calorimetry. Likewise, the protein surface hydrophobicity and the solubility of myofibrillar proteins were measured. High pressure (600 MPa) induced the loss of α-helix structures and an increase of β-sheet structures. However, the presence of xanthan gum hindered the former mechanism of protein denaturation by high pressure. In fact, changes in the secondary (600 MPa) and the tertiary structure fingerprint of high-pressure-treated myofibrillar proteins (400 to 600 MPa) were observed in the presence of xanthan gum. These modifications were confirmed by the thermal analysis, the thermal transitions of high-pressure (400 to 600 MPa)-treated myofibrillar proteins were modified in systems containing xanthan gum. As consequence, the high-pressure-treated myofibrillar proteins with xanthan gum showed increased solubility from 400 MPa, in contrast to high-pressure treatment (600 MPa) without xanthan gum. Moreover, the surface hydrophobicity of high-pressure-treated myofibrillar proteins was enhanced in the presence of xanthan gum. These effects could be due to the unfolding of myofibrillar proteins at high-pressure levels, which exposed sites that most likely interacted with the anionic polysaccharide. This study suggests that the role of food additives could be considered for the development of meat products produced by high-pressure processing.

Industrial manufacturing of bread is made of empirical practices without precise knowledge of mechanisms that govern heat and mass transfer during the processes. The objective of this work is to develop a coupled heat and mass transfer model for solid foams. The model was first designed for a solid model of foam (cellulose sponge), and then applied to a real product (bread). The heat and mass transfer model was validated against experimental results. For the foam model in freezing, the transfer model revealed an inverse water content profile (more water at the surface than in the centre). Use of this model for bread reveals the concentration of ice crystals to be more important under the crust than elsewhere at the end of freezing.

International audience