Could 'Isochoric Freezing' Revolutionise Food Preservation?

The present article responds to the food engineering community's growing interest in an emerging and lauded approach to food preservation, popularised by its developers as 'isochoric freezing'. A strong campaign in the scientific literature and mass media has recently promoted this technique as a universal replacement for traditional food freezing and the frozen supply chain by highlighting a number of alleged advantages of 'isochoric freezing'. Some of these claims therefore require a more neutral and critical assessment against the background of the today's state of the art in food freezing technologies. Hence, this article spotlights several concerns regarding the plausibility, energy expenditure, resource efficiency, process rate, throughput and safety of 'isochoric freezing', as well as the correct use of food refrigeration terminology. The aspects considered are intended to make food scientists, technologists and engineers more aware of the real capabilities and the application perspectives of this still immature mode of refrigerated food processing.

Acute and two-week effects of neotame, stevia rebaudioside M and sucrose-sweetened biscuits on postprandial appetite and endocrine response in adults with overweight/obesity-a randomised crossover trial from the SWEET consortium.

BACKGROUND: Sweeteners and sweetness enhancers (S&SE) are used to replace energy yielding sugars and maintain sweet taste in a wide range of products, but controversy exists about their effects on appetite and endocrine responses in reduced or no added sugar solid foods. The aim of the current study was to evaluate the acute (1 day) and repeated (two-week daily) ingestive effects of 2 S&SE vs. sucrose formulations of biscuit with fruit filling on appetite and endocrine responses in adults with overweight and obesity. METHODS: In a randomised crossover trial, 53 healthy adults (33 female, 20 male) with overweight/obesity in England and France consumed biscuits with fruit filling containing 1) sucrose, or reformulated with either 2) Stevia Rebaudioside M (StRebM) or 3) Neotame daily during three, two-week intervention periods with a two-week washout. The primary outcome was composite appetite score defined as [desire to eat + hunger + (100 - fullness) + prospective consumption]/4. FINDINGS: Each formulation elicited a similar reduction in appetite sensations (3-h postprandial net iAUC). Postprandial insulin (2-h iAUC) was lower after Neotame (95% CI (0.093, 0.166); p < 0.001; d = -0.71) and StRebM (95% CI (0.133, 0.205); p < 0.001; d = -1.01) compared to sucrose, and glucose was lower after StRebM (95% CI (0.023, 0.171); p < 0.05; d = -0.39) but not after Neotame (95% CI (-0.007, 0.145); p = 0.074; d = -0.25) compared to sucrose. There were no differences between S&SE or sucrose formulations on ghrelin, glucagon-like peptide 1 or pancreatic polypeptide iAUCs. No clinically meaningful differences between acute vs. two-weeks of daily consumption were found. INTERPRETATION: In conclusion, biscuits reformulated to replace sugar using StRebM or Neotame showed no differences in appetite or endocrine responses, acutely or after a two-week exposure, but can reduce postprandial insulin and glucose response in adults with overweight or obesity. FUNDING: The present study was funded by the Horizon 2020 program: Sweeteners and sweetness enhancers: Impact on health, obesity, safety and sustainability (acronym: SWEET, grant no: 774293).

Post-sprouting thermal treatment of green barley malt to produce functional clean-label ingredients: Impact on fermentation, bread-making properties and bread quality.

Malt flour represents a potential clean label bread improver, but a high enzymatic activity can lead to some bread defects. Thus, this study was focused on applying different thermal treatments (10 and 40 min; 70-90 °C) to green barley malt in order to promote a partial enzyme inactivation. The addition of 1.5 g of thermally treated malt (TTM) per 100 g of flour in wheat bread formulation was evaluated regarding the resulting bread-making properties, dough fermentation and overall bread quality. Activity of starch-degrading enzymes was not detectable above 80 °C/10 min. TTM incorporation improved the gas production by up to 60% during fermentation, mainly in formulations to which malts thermally treated under mild conditions have been added. Compared to untreated malt, thermal treatment reduced dough thermal weakening, improved gel strength during gelatinization and maintained low setback values. Bread collapse observed by baking follow-up was related to gas inflation and low mechanical resistance. Formulations with the addition of malts thermally treated at 70 °C for 40 min resulted in breads with higher specific volume, improved coloration and a crumb with slightly smaller pores than control and untreated malts. Thus, thermal treatment can be used as a technique to produce standardized malted flour to be used as clean label bread improvers.

Impact of Baking Powder and Leavening Acids on Batter and Pound Cake Properties.

In most soft wheat products such as cakes, baking powder (BP) plays an important role in achieving the desired product volume through batter aeration by the release of CO2 during baking. However, the optimization of a blend of constituents in BP is minimally documented, especially the selection of acids, which is often supported by the suppliers based on their experience. The objective of this study was to evaluate the impact of two sodium acid pyrophosphate leavening acids (SAPP10 and SAPP40) at different levels in BP on final pound cake properties. A central composite design of the response surface methodology (RSM) was used to design the blend ratio of SAPP with different amounts of BP to investigate some selected cake parameters such as specific volume and conformation. Results showed that increasing the BP level significantly increased the batter specific volume and porosity but dropped as BP approached maximum (4.52%). The batter pH was influenced by SAPP type; SAPP40 presented a relatively sufficient neutralization of the leaving system as compared to SAPP10. Furthermore, lower BP levels resulted in cakes with large air cells, which presented a non-homogeneous crumb grain. This study therefore highlights the need to identify the optimum amount of BP to attain the desired product qualities.

Effects of Sucrose Replacement by Polyols on the Dough-Biscuit Transition: Understanding by Model Systems.

This study investigated the impacts of the complete substitution of sucrose by maltitol and/or sorbitol on the dough-crumb transition in biscuits. To this end, the phenomena of starch gelatinization/melting were studied at different moisture contents, both in the biscuit dough and model systems, by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and by environmental scanning electron microscopy (ESEM). Observation of doughs in ESEM revealed sorbitol had a structure very different from sucrose and maltitol crystals. After forming the dough pieces, it could be seen that at least some sugar and maltitol crystals were still present while sorbitol flakes were solubilized. At a limiting real water content (~20% dry basis), adding sweeteners to the mixture increased the gelatinization temperature, more markedly for sucrose and maltitol, as well as increasing the enthalpy. These results were confirmed by the model systems analyses. The calorimetric study with mixing batch cells revealed that sorbitol dissolved completely while maltitol and sucrose competed with the flour constituents to capture water. The proportion of water available for the sorption of the starch grain and its gelatinization was therefore different according to the affinity of the sweetener for water, and might influence the degree and temperature of starch gelatinization/melting.

Clean-label techno-functional ingredients for baking products - a review.

The increased awareness of consumers regarding unfamiliar labels speeded up the ongoing clean label trend. As baking products are widely consumed worldwide, the reduction of non-natural baking aids and improvers is of great interest for consumer's health but also representing a big challenge for food industries. Thus, this paper aims at describing new techno-functional clean label ingredients for baked products and their production processes conditions. Firstly, it includes ingredients such as sustainable protein sources, fat replacers and leavening alternatives. Then, it addresses new process alternatives for producing baking ingredients with natural claim as well as current concepts as the natural fermentation. In particular, molecular and functional modifications of the flour are discussed regarding malting and dry heat treatments. By being considered as green and emerging technologies that improve flour functionality, the resulting ingredients can replace additives. Changes in quality and technological attributes of breads and cakes will be discussed as a consequence of the partial to total replacement of conventional ingredients. This paper provides new alternatives for the baking industry to meet the demand of a growing health-concerned population. In addition, it focused on opening up new possibilities for the food industry to go in line with the consumers' expectations.

Impact of Maltitol and Sorbitol on Technological and Sensory Attributes of Biscuits.

Overconsumption of sugars in diets is associated with many health problems, including dental diseases, diabetes and obesity. However, removing sugar from products such as biscuits is still a challenge for manufacturers and has been limited in Europe since the evolution of the EU regulation in January 2018, allowing only polyols and non-sweetening bulking agents as sugar substitutes. This study investigated the effects of fully replacing sugar with two polyols, maltitol and sorbitol, in short-dough biscuits. Morphological, textural and visual characteristics were studied as well as sensory properties. The reformulated biscuits were more compact in shape and structure. They were also less prone to checking, which was attributed to a more homogeneous water distribution at the end of baking, especially with sorbitol. Polyol biscuits were surprisingly colourful, especially sorbitol ones, although polyols are not normally involved in Maillard reactions. Sensory tests, however, showed a depreciation of the products compared to the control. Sorbitol biscuits were the least preferred but maltitol ones were quite well accepted compared to the control. Thus, maltitol is an excellent potential substitute for this type of product.

Starch modification through environmentally friendly alternatives: a review.

Starch is a versatile and a widely used ingredient, with applications in many industries including adhesive and binding, paper making, corrugating, construction, paints and coatings, chemical, pharmaceutical, textiles, oilfield, food and feed. However, native starches present limited applications, which impairs their industrial use. Consequently, starch is commonly modified to achieve desired properties. Chemical treatments are the most exploited to bring new functionalities to starch. However, those treatments can be harmful to the environment and can also bring risks to the human health, limiting their applications. In this scenario, there is a search for techniques that are both environmentally friendly and efficient, bringing new desired functionalities to starches. Therefore, this review presents an up-to-date overview of the available literature data regarding the use of environmentally friendly treatments for starch modification. Among them, we highlighted an innovative chemical treatment (ozone) and different physical treatments, as the modern pulsed electric field (PEF), the emerging ultrasound (US) technology, and two other treatments based on heating (dry heating treatment - DHT, and heat moisture treatment - HMT). It was observed that these environmentally friendly technologies have potential to be used for starch modification, since they create materials with desirable functionalities with the advantage of being categorized as clean label ingredients.

Influence of the Presence of Choline Chloride on the Classical Mechanism of "Gelatinization" of Starch.

The aim of this research is to contribute to a better understanding the destructuration of three native starches and a wheat flour in mixtures of water and choline chloride. Model systems have thus been defined to allow a better approach to hydrothermic transformations related to the interactions between choline chloride and starch. We have observed that choline chloride has an impact on the gelatinization of starch which corresponds to the stabilizing salts phenomenon. The depolymerization and dissolution of the starch have also been demonstrated and can there dominate the gelatinization. However, the results obtained in X-ray diffraction by heating cell have shown that the exotherm which appeared was not only related to the depolymerization of the starch, but that a stage of crystalline rearrangement of the starch coexisted with this phenomenon.

Study of structural changes of gluten proteins during bread dough mixing by Raman spectroscopy.

The aim of the present study was to evaluate Raman spectroscopy in determining changes that occur in the structure of gluten proteins induced during bread dough mixing. Raman spectra were measured directly within the dough. Three particular phases of mixing were studied: under-mixing, optimum mixing and over-mixing. A thiol blocking reagent, Tris(2-carboxyethyl)phosphine (TCEP) was then used to reduce disulphide bonds within proteins to confirm the important role of disulphide bridges in gluten network formation. For the control dough, the most important changes occurred during the optimum mixing phase when an increase in intermolecular disulphide bonds, anti-parallel ß-sheet and α-helix structures was observed, combined with the hydrophobic burial of tryptophan and tyrosine residues. The addition of TCEP appeared to effectively reduce the formation of intermolecular disulphide bonds, anti-parallel ß-sheet and α-helix structures and lead to a more disordered secondary protein structure.

Effect of long-term storage conditions on wheat flour and bread baking properties.

This paper presents a study on the effect of storage conditions on wheat flour quality for 30 months. Such study may be of interest for research projects conducted over long periods. Wheat flours were stored in two types of packaging (permeable paper bags and watertight containers) and at two temperatures (ambient temperature and a cold storage room). Selected qualities parameters were evaluated regularly such as chemical stability, consistency, extensibility, resistance, water absorption, Solvent Retention Capacity and Gluten Index Performance. In addition, Near-Infrared Spectroscopy was used to monitor the flour's evolution and models were employed to predict certain parameters. The results showed that storage at ambient temperature led to significant modifications of flour parameters and baking performances, whereas storage at low temperature preserved the initial quality of the flour. A practical recommendation is to favour storage at low temperature in a sealed container to prevent interaction with oxygen and moisture uptake.

Dual-process of starch modification: Combining ozone and dry heating treatments to modify cassava starch structure and functionality.

This work evaluated for the first time the effect of dual modification of cassava starch by using ozone (O3) and dry heating treatment (DHT). The dual modification was capable to promote fissures on the surface of the starch granule (DHT + O3), affected the starch amorphous domains, presented greater degree of starch oxidation (DHT + O3) and different profiles of starch molecular size distribution. These modifications resulted in starches with different properties. Moreover, the sequence of treatments was decisive for the hydrogel properties: while DHT + O3 resulted in formation of stronger gels, O3 + DHT resulted in weaker gels. In conclusion, this proposed dual modification was capable to produce specific modified starch when compared with the isolated treatments, also expanding the potential of cassava starch applications.

Dry heating treatment: A potential tool to improve the wheat starch properties for 3D food printing application.

The futuristic technology of three-dimensional (3D) printing is an additive manufacturing that allows obtaining creative and personalized food products. In this context, the study of food formulations (named as "inks") to be processed through 3D printing is necessary. This work investigated the use of dry heating treatment (DHT), a simple and safe method, to improve the wheat starch properties aiming to produce hydrogels to be used as "inks" for 3D printing. Wheat starch was processed by dry heating for 2 (DHT_2h) and 4 h (DHT_4h) at 130 °C. Modified wheat starches showed an increase in granule size, but processing did not alter the granule's shape nor surface, neither alter the molecular functional groups. On the other hand, DHT promoted slight molecular depolymerization, and reduction of starch crystallinity. Hydrogels "inks" based on the modified starches showed lower peak apparent viscosity during pasting, higher structural strength at rest, higher resistance to external stresses, higher gel firmness, and lower syneresis than hydrogels based on native starch. The hydrogels based on starch DHT_4h showed the best printability (greater ability to make a 3D-object by layer-by-layer deposition and to support its structure once printed) and this "ink" showed better reproducibility. Another point observed is that DHT extended the texture possibilities of printed samples based on wheat starch hydrogels. These results suggested that DHT is a relevant process to improve the properties of hydrogels based on wheat starch, making this ink suitable for 3D printing application.

Preparation of cassava starch hydrogels for application in 3D printing using dry heating treatment (DHT): A prospective study on the effects of DHT and gelatinization conditions.

3D printing is a technology capable of presenting creative, unique and intricate items in an attractive format, with specific compositions. However, novel ingredients must be developed to satisfy this new technological requirement. This work proposes dry heating treatment (DHT), a simple physical technique, as a method for modifying cassava starch, with particular focus on its use for 3D printing. DHT processing was conducted at 130 °C for 2 and 4 h (named DHT_2h and DHT_4h, respectively). Different gelatinization conditions (65, 75, 85, and 95 °C) were applied, and the hydrogels were evaluated considering different storage periods (1 and 7 days). Cassava starch properties were evaluated, focusing on the application of its hydrogels to 3D printing. The increase of DHT time produced a starch with higher carbonyl content and bigger granule size. It also reduced the water absorption index, increased the water solubility index, affected granule crystallinity and reduced molecular size. The longest storage period increased gel firmness. Increasing the temperature used in the gelatinization process reduced the gel strength of the native and DHT_2h. DHT_4h showed the lowest peak apparent viscosity and provided the strongest gels for all the evaluated conditions. Gels produced with DHT starches exhibited better printability than the native starch, mainly for the DHT_4h. This treatment was chosen to print 3D stars, and displayed better resolution than the native gels. Therefore, by using DHT, it was possible to obtain hydrogels with enhanced pasting properties, gel texture, and printability, thereby expanding the potential of applying cassava starch to 3D printing.

Effect of innovative microwave assisted freezing (MAF) on the quality attributes of apples and potatoes.

This study considered the effect of low energy microwave assisted freezing (MAF) on freezing time and quality attributes (microstructure, texture, drip loss and colour) of apple and potato. MAF of apples and potatoes was performed by applying constant microwave (MW) power (167 W/kg) and pulsed MW power (500 and 667 W/kg with 10 s pulse width and 20 s pulse interval resulting in an average power of 167 and 222 W/kg) during the freezing process. The temperature profile was monitored during the freezing process, and the microstructure was examined using X-ray micro-tomography and cryo-SEM. Other quality parameters such as texture, drip loss and colour were evaluated with thawed samples. It appeared that the freezing time was not affected by the MAF process. It is the first time that a MAF process is used for freezing plant-based products and showed that the application of microwaves during freezing process caused less freeze damage than the control condition.

Hydrogels based on ozonated cassava starch: Effect of ozone processing and gelatinization conditions on enhancing 3D-printing applications.

Ozone is an interesting alternative for modifying starch, as it is considered an emerging and environmentally friendly technology. New applications for food ingredients are receiving attention, such as 3D printing. Consequently, the impact of emerging technologies on new applications must be understood. In this work, cassava starch was modified by ozone to evaluate its printability. Increasing ozonation time produced a starch with higher carbonyl and carboxyl contents, lower pH and molecular size, and gels with different behaviors (stronger and weaker than the native ones, as a function of processing time). The hydrogels obtained were evaluated in relation to pasting and gel properties, including their printability. The effects of starch concentration, gelatinization temperature and storage period were also evaluated. Starch ozonated for 30 min showed the lowest peak apparent viscosity at all the temperatures and starch concentrations evaluated, and provided the strongest gel. Gels produced by native starches and starches ozonated for 30 min showed good printability when the gelatinization temperature used was 65 °C, but up to this temperature, only starch ozonated for 30 min produced gels with good printability. This work highlights that, by using the ozone process to modify starch and varying the process conditions, it is possible to obtain hydrogels with enhanced pasting properties, gel texture, and printability, thereby expanding the potential of starch applications.

Assessment of freeze damage in fruits and vegetables.

Freezing is an efficient and widely used method of food preservation. However, it can also cause irreversible damages at cellular level which in turn degrade the overall quality of the frozen food products. Therefore, qualitative and quantitative methods and technologies that will be able to evaluate with accuracy the freeze damage are of great importance. This review paper provides a comprehensive study of the methods that have been used to evaluate the freeze damage in fruits and vegetables. Further than the principles and the applications of those methods, the advantages and the limitations are also being discussed.

Vitamin B4 as a salt substitute in bread: A challenging and successful new strategy. Sensory perception and acceptability by French consumers.

Numerous scientific studies have shown that overconsumption of salt can be harmful and promotes the development of cardiovascular diseases. For this reason, many international organizations and government agencies aim to reduce overall salt consumption from food. Recent exploratory work has shown that vitamin B4 can play the role of salt substitute. This study aims on the one hand to develop and optimize a bread recipe reduced in salt and enriched with vitamin B4. On the other, it aims to study the acceptability for consumers of this double innovation, combining the addition and withdrawal of a nutrient. The study was conducted with French consumers. The sensory test showed that vitamin B4 tends to increase the perception of salt in salt-reduced bread. The acceptance of reduced-salt and vitamin B4-enriched bread was investigated in three focus-groups, mixing blind tests, information input and spontaneous evocations. Three potential targets have been identified: health-oriented young people, young parents who want to educate children to engage in a healthy lifestyle, and people broadly sensitive to nutritional information. Consumers with a pleasure and taste-oriented profile were more skeptical of the new bread formula because of greater attachment to traditional, salty French bread.

Impact of local hydrothermal treatment during bread baking on soluble amylose, firmness, amylopectin retrogradation and water mobility during bread staling.

The impact of hydrothermal processing undergone by bread dough during baking on the degree of starch granule disruption, on leaching of soluble amylose, on water mobility, on firmness and on amylopectin retrogradation during staling has been investigated. Two heating rates during baking have been considered (4.67 and 6.31 °C/min) corresponding respectively to baking temperature of 220 and 240 °C. An increase in firmness and in the amount of retrogradated amylopectin accompanied by a decrease in freezable water has been observed during staling. Although a lower heating rate yielded in larger amount of retrogradated amylopectin retrogradation, it resulted in a lower firmness. Additionally, the amount of soluble amylose and the relaxation times of water measured by Nuclear Magnetic Resonance NMR (T20, T21 and T22) decreased during staling. It was demonstrated that the amount of soluble amylose was higher for bread crumb baked at lower heating rate, indicating that an increasing amount of amylose is leached outside the starch granules. This was corresponding to a greater amount of retrograded amylopectin during staling. Moreover, it was found that the degree of gelatinization differs locally in a same bread slice between the top, the centre and the bottom locations in the crumb. This was attributed to the differences in kinetics of heating, the availability of water during baking and the degree of starch granule disruption during baking. Based on first order kinetic model, it was found that staling kinetics were faster for samples baked at higher heating rate.

The principles of high voltage electric field and its application in food processing: A review.

Food processing is a major part of the modern global industry and it will certainly be an important sector of the industry in the future. Several processes for different purposes are involved in food processing aiming at the development of new products by combining and/or transforming raw materials, to the extension of food shelf-life, recovery, exploitation and further use of valuable compounds and many others. During the last century several new food processes have arisen and most of the traditional ones have evolved. The future food factory will require innovative approaches food processing which can combine increased sustainability, efficiency and quality. Herein, the objective of this review is to explore the multiple applications of high voltage electric field (HVEF) and its potentials within the food industry. These applications include processes such as drying, refrigeration, freezing, thawing, extending food shelf- life, and extraction of biocompounds. In addition, the principles, mechanism of action and influence of specific parameters have been discussed comprehensively.