Effect of high pressure homogenization (HPH) on the rheological properties of tomato juice: Viscoelastic properties and the Cox–Merz rule

High pressure homogenization (HPH) is a non-thermal technology which has been widely studied as a partial or total substitute for the thermal processing of food. Although microbial inactivation has been widely studied, there are only a few papers in the literature reporting on physicochemical changes in fruit products due to HPH, especially regarding their rheological properties. The present work evaluated the effect of HPH (up to 150 MPa) on the viscoelastic properties of tomato juice. HPH increased the tomato juice storage (G′) and loss (G″) moduli. The parameters G′ and G″ were modelled as a power function of the oscillatory frequency (ω), and then evaluated as a function of homogenization pressure. It was observed that HPH processing improved tomato juice consistency more than it modified its nature/behaviour. The changes observed in the viscoelastic properties were attributed to disruption of the suspended particles during processing. Moreover, two modified Cox–Merz rules were used to correlate the products steady-state shear properties with viscoelasticity. The results obtained indicated that this process could be used to improve both product elastic and viscous behaviour, highlighting possible applications of the HPH process as a valuable tool to promote physical property changes in food products.     

Protein glycosylation: a promising way to modify the functional properties and extend the application in food system

Abstract

Modification of functional properties by glycosylating with polysaccharides is an effective solution to improve the internal disadvantages of native proteins. Generally, protein glycosylation belongs to the first stage of the Maillard reaction in essence. Dry-heating, wet-heating, and their combination are the major methods for the preparation of protein-polysaccharide conjugates (PPC). Spectrophotometry, spectroscopy, electrophoresis, calorimetry, chromatography, and mass spectrometry are confirmed to be the most effective methods for the identification of PPC. After glycosylation, functionalities of the native protein, including solubility, rheological properties, emulsifying properties, foaming properties, gel property, film-forming properties, thermal stability, antioxidant activity, allergenicity, and antibacterial properties, are improved. The PPC is extensively used as an encapsulation or a delivering material in order to improve the bioaccessibility of bioactive compounds in food system. Some new applications in food processing could be explored using PPC as an ingredient based on the improved functional properties, such as 3-dimensional printing food, gelled food, and colloid food. Furthermore, the model of protein glycosylation and the application of PPC in food processing could be extended to other protein modification to broaden the exploitation of native protein resource for the processing of novel foods.     

Developing novel 3D measurement techniques and prediction method for food density determination

Density is a physical characteristic which depends on the experimental technique used and structural properties of food. True, apparent, and bulk are different types of densities based on the way volume is measured. For porous foods such as grain food products, accurate measurement of density is challenging. Current measurement techniques for food density are inconsistent and nutrient databases do not have sufficient density data. Computed tomography (CT) and magnetic resonance imaging (MRI), laser scanners are non-destructive diagnostic tools for characterizing food microstructure. The objectives of this study were to 1) optimize the parameters of CT, MRI, and laser scanner to determine food density and compare the corresponding values with other traditional techniques, and 2) to develop neural networks as a prediction method for apparent and bulk densities. MicroCT 40 (Scano Medical Inc.), Lightspeed QX/i clinical CT (GE Healthcare), and 3 Tesla Signa HDx MRI (GE Healthcare) were used to acquire 3D images of foods for true density. A 3D laser scanner (NextEngine, Inc) was used to scan the foods items for apparent density. Neural networks were used in conjunction with the data collected from laser scanner and using food composition and processing conditions to generate a black-box prediction scheme. The results of CT, MRI, and laser scanner showed great potential to estimate density in comparison to traditional techniques. Porosity was estimated from the CT and MRI scanned image data. Laser scanner was successful in acquiring 3D images and calculating apparent density. Neural networks provided reliable density prediction power and were comparable to the other empirical equations in terms of accuracy. The ability to predict food density based on composition and processing conditions is necessary to fill gaps in nutrient databases and account for new foods.     

Application of differential scanning calorimetry to estimate quality and nutritional properties of food products

Over the past years, both food researchers and food industry have shown an increased interest in finding techniques that can estimate modifications in quality, nutritional, and thermophysical properties of food products during processing and/or storage. For instance, differential scanning calorimetry (DSC) has attracted the interest of scientific community because only a small amount of sample is needed for analysis. Moreover, it does not require any specific sample preparation, and is a repeatable and reliable method. In addition, DSC methodology needs a short time for experiments compared with other techniques used for the same purpose. At this stage of investigation, there is a need to evaluate the commonly accepted and new emerging DSC applications to establish the optimum conditions of emerging processing. This paper reviews the current and new insights of DSC technique for the estimation of quality, nutritional, and thermophysical properties of food products during conventional and emerging processing and/or subsequent storage. The estimation of different properties in several food matrices after processing and/or storage is also discussed.     

Mung Bean: Technological and Nutritional Potential

Mung bean (Vigna radiata (L.) R. Wilczek) has been intensively researched; scattered data are available on various properties. Data on physical, chemical, food processing, and nutritional properties were collected for whole mung bean grains and reviewed to assess the crop's potential as food and to set research priorities. Results show that mung bean is a rich source of protein (14.6–33.0 g/100 g) and iron (5.9–7.6 mg/100 g). Grain color is correlated with compounds like polyphenols and carotenoids, while grain hardness is associated with fiber content. Physical properties like grain dimensions, sphericity, porosity, bulk, and true density are related to moisture content. Anti-nutrients are phytic acid, tannins, hemagglutinins, and polyphenols. Reported nutrient contents vary greatly, the causes of which are not well understood. Grain size and color have been associated with different regions and were used by plant breeders for selection purposes. Analytical methods require more accuracy and precision to distinguish biological variation from analytical variation. Research on nutrient digestibility, food processing properties, and bioavailability is needed. Furthermore, the effects of storage and processing on nutrients and food processing properties are required to enable optimization of processing steps, for better mung bean food quality and process efficiency.     

电子计算机在热过程计算中的应用

本文为罐头食品热过程计算发展了一个计算机程序。这个计算机程序使用了一组温度方程和致死率积分公式。由于所使用的温度方程含有两个在罐头工业中最广泛使用的实验参数:j和f值,因此程序使用简便,可靠,而且适用于对流加热和传导加热食品。该程序可用于解决简单型加热食品和有一个转折点的转折型加热食品的两类热过程计算问题。     

Thermal properties of batter systems formulated by combinations of different flours

There is an increasing consumer preference for reduced oil content in fried food products. The amount of fat absorbed by deep fried foods can be modified using appropriate coatings such as batter and breading systems. Coatings also change the heat transfer characteristics of the composite products. The goal of this study was to determine some thermal properties of selected batter mixes that are commonly used for deep fat frying of chicken products. Three types of flour-based batter mixes were used. These were mixtures of wheat and rice (WR), wheat and corn (WC), and corn and rice (CR) flours with salt and different methylcellulose (MC) levels. The differential scanning calorimeter (DSC) was used to measure glass transition temperature (T_g), gelatinization temperature (T_G), ice-melting temperature (T_m) and enthalpy (ΔH_G) of the different batter formulations. Salt and MC greatly influenced the thermal properties of batter systems as they increased T_G, but depressed T_m. Adding rice and corn flours to wheat flour based batters apparently changed the thermal properties. Corn flour based batters required considerable more energy for gelatinization during the cooking process.     

Effects of Oxygen and Water Vapor Transmission Rates of Polymeric Pouches on Oxidative Changes of Microwave-Sterilized Mashed Potato

Polymer-based packaging with low oxygen (OTR) and water vapor transmission rates (WVTR) can be used to limit oxidative chemical changes in packaged foods, especially for the 3- to 5-year shelf life required for military rations and long-duration space foods. Microwave-assisted thermal sterilization (MATS) produces higher quality food with a potentially longer shelf life as a result of volumetric heating and the associated shorter process time. This study investigated the effects of the package-MATS process interactions and the resultant package barrier properties on food quality, using a mashed potato model food following MATS process of F₀?=?9 min for 12 weeks at 50 °C. Two poly ethylene terephthalate (PET)-based (MFA, MFC) and one ethylene vinyl alcohol (EVOH)-based (MFB) retort pouches were tested, with OTRs of 0.20, 2.11, and 0.07 cc/m²·day and WVTRs of 2.64, 1.78, and 0.29 g/m²·day for MFA, MFB, and MFC, respectively; a foil double-sealed MFA pouch served as a control (MF0).Barrier properties did not influence oxygen content in polymer pouches during storage (p?>?0.05). From the third week to the fifth week of storage, significant differences (p?<?0.05) were observed in total color difference (ΔE) and oxidation indicators (TBARS, hexanal, and nonanal). The mashed potato treated in higher barrier property pouches exhibited less color change and oxidation than those in lower barrier property pouches. The performance of the MFC pouch was similar overall to that of the metal pouch. These findings suggested that high-barrier packages are suitable for MATS or other commercially sterile foods, particularly for long shelf-life purpose.     

Growth potential of Clostridium perfringens during cooling of cooked meats

Many meat-based food products are cooked to temperatures sufficient to inactivate vegetative cells of Clostridium perfringens, but spores of this bacterium can survive, germinate, and grow in these products if sufficient time, temperature, and other variables exist. Because ingestion of large numbers of vegetative cells can lead to concomitant sporulation, enterotoxin release in the gastrointestinal tract, and diarrhea-like illness, a necessary food safety objective is to ensure that not more than acceptable levels of C. perfringens are in finished products. As cooked meat items cool they will pass through the growth temperature range of C. perfringens (50 to 15 degrees C). Therefore, an important step in determining the likely level of C. perfringens in the final product is the estimation of growth of the pathogen during cooling of the cooked product. Numerous studies exist dealing with just such estimations, yet consensual methodologies, results, and conclusions are lacking. There is a need to consider the bulk of C. perfringens work relating to cooling of cooked meat-based products and attempt to move toward a better understanding of the true growth potential of the organism. This review attempts to summarize observations made by researchers and highlight variations in experimental approach as possible explanations for different outcomes. An attempt is also made here to identify and justify optimal procedures for conducting C. perfringens growth estimation in meat-based cooked food products during cooling.     

Simple Method to Compute Biases and Mean Squared Errors of Linear Estimators and Predictors in a Selection Model Assuming Multivariate Normality

Evaluation of biases and mean squared errors of predictors by analytical methods is difficult when selection has occurred. Traditional simulation methods are very costly because of many possible incidence matrices, parameter values, and methods of prediction. Assuming multivariate normality and the Pearson model for selection, numerical solutions to evaluation of biases and mean squared errors can be obtained by use of distributions that are conditional on selection. A linear predictor and estimator is tested for bias by computing with conditional y and then comparing the solution to β and u with true β and conditional u. Mean squared errors are computed by adding to the conditional variance a quadratic in the bias evaluated for the estimation and prediction method that was examined. A numerical example involving cow culling is used to illustrate the methods.     

Assessing mineral composition and morpho-physiological properties of de-hulled einkorn wheat during storage at different moisture levels

In this study were investigated the effects of different moisture levels (4.8, 9.5, 13, 16.7 and 20%, w.b.) during the storage at 10 °C for three months on some mineral compositions and morpho-physiological properties as dimensional (length, width, thickness, arithmetic mean diameter, geometric mean diameter, surface area and volume, sphericity), gravimetric (thousand grain weight, bulk and true densities) and the seed (colour measurement and electrical conductivity) of de-hulled einkorn wheat seeds. Mineral composition of wheat seeds changed with increasing moisture level. In particular, decreases in mineral composition were observed above 16.7% moisture level. Dimensional properties showed increases depending on increased moisture level. It was found that thousand grain weight and true density values increased with increase in moisture level. However, bulk density values were found to decrease with increase in moisture level. The seed colour properties as L*, a*, b*, Chroma, hue angle and Browning index did not change statistically at the end of three months storage with increase at moisture level. The results showed that mineral compositions and functional properties of seeds at moisture level of 9.5% is more suitable than other moisture levels. As a result, high moisture levels during storage can cause degradation of seed quality.     

甘草甜素的生理功能及其在食品工业中的应用

甘草甜素是从药用植物甘草根茎中提取出来的一种具有多种生理功能的有效活性成分。因其具有良好的味感和多种功能性质，作为一种天然甜味剂在食品工业中具有广阔的应用前景。本文就甘草甜素理化性质、功能特性、生理功能及其在食品工业中的应用做一综述，并对其开发应用前景进行了展望。     

An investigation of the dielectric and thermal properties of frozen foods over a temperature from –18 to 80°C

The dielectric properties (dielectric constant [ε′] and dielectric loss factor [ε″]) for three frozen meals (basil fried chicken, green curry with chicken, and congee with minced pork) were measured at frequency 2.45 GHz from –18 to 80°C. Thermal properties (thermal conductivity [k] and specific heat capacity [c]) of each food item were characterized using their composition for improving the modeling of microwave thawing process of frozen products. For all frozen meals, similar trends in the dielectric and thermal properties values were observed as a function of temperature. In all samples of frozen foods, the dielectric properties (ε′, ε″) rapidly increased with temperature for the range from –10 to 0°C. Thereafter, dielectric properties linearly increased with temperature for basil fried chicken and congee with minced pork but linearly decreased with temperature for green curry with chicken from 0 to 80°C. The dielectric properties data bases were used to calculate power reflected (P_r), power transmitted (P_t), dielectric loss tangent (tanδ), and penetration depth (d_p). These parameters were related to the dielectric properties. The thermal conductivity values of all samples decreased with increasing temperature in the frozen stage and little changed after thawing. While the specific heat capacity values increased first and then do not change considerably. The temperature-dependent material properties can give insight into how the food product interacts with the incident electromagnetic radiation.     

Modeling inactivation of Clostridium botulinum and vitamin destruction of non-Newtonian liquid-solid food mixtures by convective sterilization in cans

Unsteady fluid mechanics and convective heat transfer in the sterilization of canned tuna chunks immersed in a non-Newtonian fluid by a Darcy-Brinkmann-Forchheimer porous model has been studied numerically by a conjugate mathematical model. The coupled equations were solved by the Finite Volume method with the SIMPLE algorithm. The model developed related the sterilization time and temperature distribution with the kinetics of C. botulinum inactivation and the degradation of two relevant vitamins in canned tuna, riboflavin, and thiamin. Additionally, the effect of the covering liquid in the sterilization process and nutrients loss from canned tuna was investigated. The results showed that the sterilization time decreases in fluids with low viscosity, as water and brine, compared to CMC. The cases investigated had a different response to achieve complete sterility, considering the preservation of nutrients. Obtaining a balance between operating time and energy cost allows improving the process to make it more efficient.Industrial relevanceModeling of bacteria inactivation and vitamin degradation in liquid-solid food mixtures is of great interest because the extended number of relevant food processes involve heat transfer in these matrices, where is mandatory an accurate estimation of time and conditions essential for a complete sterilization process.     

Can we improve global food security? A socio-economic and political perspective

Ensuring global food security for a growing population remains a major challenge. This is especially true against the background of increasing food prices paired with growing income levels and changing demand patterns in the developing world. At the same time, climate change and the occurrence of more frequent and extreme natural disasters increase the vulnerability of rural farm households, negatively affecting agricultural production. Given the many dimensions of food security, no simple solution can be found. Promoting productivity of farming and increasing the efficiency of the food marketing system are effective measures contributing to rural development in developing countries. Policy reforms in agriculture and beyond help to reduce distortions and change consumers’ awareness with respect to food waste and resource use inefficiencies related to human diets. What is new in this context is the increasing link of agriculture with other sectors such as the energy and the financial markets. This calls for further research as additional pressure is being put on the global food system.     

VIEWS ON RELATING INSTRUMENTAL TESTS TO SENSORY ASSESSMENT OF FOOD TEXTURE. APPLICATIONS TO PRODUCT DEVELOPMENT AND IMPROVEMENT 1,2

Well-defined measurements of the mechanical properties of food and the reduction of sensory attributes to the fundamental primary entities, together with the definition of their correlation functions, provide the basis for the eventual development of instruments calibrated in terms of human sensory response and having a high probability of predicting the consumer reaction. Since mechanical measurements of most foods are time-dependent, the understanding of conditions prevailing during sensory testing (rate of shear, etc.) will aid in selecting the optimum conditions for instrumental testing. Recent progress in this area has been made with fluids and some solid foods. The method of magnitude estimation assists the researcher in discovering the underlying laws relating physical product changes to perceived textural changes. At the same time, magnitude estimation also aids the product developer to determine empirical, ad hoc relations between physical levels of mechanical variables and textural perceptions, even if the true, underlying relationships are not known. Ad hoc equations can be used (in conjunction with optimization techniques) to determine the combination of mechanical variables that (a) produce a specific sensow texture profile, and (b) maximize texture/product acceptability.     

超声波技术在发酵食品领域的应用

发酵是一种古老的技术,主要用于保存易腐烂的食物。而发酵食品通常比原材料具有更多优点,例如安全、更加稳定,并具有独特的感官和营养属性以及治疗特性。目前发酵食品在食品市场中占据重要地位(产品占有率约80%以上)。随着生物工程技术的进步,发酵食品领域也在同步快速增长和创新。超声波作为一种新兴的非热食品加工技术,可以通过其对发酵剂、食品基质和两者之间相互作用的影响,用于提高发酵过程的效率,并改善发酵食品的感官和功能特性。因此,本文综述了超声波作为一种加工或分析技术在食品发酵中的众多应用,总结了其对发酵产品功能特性的影响,以期为后续研究提供参考。     

The effect of starch isolation method on physical and functional properties of Portuguese nuts starches. I. Chestnuts (Castanea sativa Mill. var. Martainha and Longal) fruits

The functionality of starch from chestnut (Castanea sativa Mill.) fruits isolated by alkaline and enzymatic methods were assessed. The studied properties included: solubility, swelling power, pasting properties, synaeresis, turbidity, and thermal and rheological behaviours. In addition amylose and resistant starch content were also evaluated. Results showed that the starch isolation method induced changes in most of those properties. Extracted starches (with high contents of amylose and resistant starch) showed low and similar swelling solubility values for all of the samples. Gelatinisation temperatures were also similar (61.5-63.0 °C), but the enzymatic method induced lower consistencies at 95 °C and after holding at this temperature. High values of setback were found, which were clearly affected by the isolation method. This parameter presented lower values for starches isolated by alkaline method (160 BU and 235 BU, respectively for Martainha and Longal). Starches did not present a peak consistency during pasting. Turbidity and synaeresis values were low at room temperature. Synaeresis increased when pastes were stored at low temperatures. This effect was more evident for the material isolated by enzymatic method. All of the isolation starches presented low enthalpy values (3.0-3.5 J/g), but the activation energy was higher for Martainha starches and for starches isolated by A3S method. Pastes showed viscoelastic behaviour, with a predominance of elastic property, forming strong gels after cooling. Longal variety seems to be less resistant to the effect of isolation method. In general starches isolated by the alkali method present the best functional properties as a food ingredient.     

Rational Design of Amyloid‐Like Fibrillary Structures for Tailoring Food Protein Techno‐Functionality and Their Potential Health Implications

To control and enhance protein functionality is a major challenge for food scientists. In this context, research on food protein fibril formation, especially amyloid fibril formation, holds much promise. We here first provide a concise overview of conditions, which affect amyloid formation in food proteins. Particular attention is directed towards amyloid core regions because these sequences promote ordered aggregation. Better understanding of this process will be key to tailor the fibril formation process. Especially seeding, that is, adding preformed protein fibrils to protein solutions to accelerate fibril formation holds promise to tailor aggregation and fibril techno‐functionality. Some studies have already indicated that food protein fibrillation indeed improves their techno‐functionality. However, much more research is necessary to establish whether protein fibrils are useful in complex food systems and whether and to what extent they resist food processing unit operations. In this review the effect of amyloid formation on gelation, interfacial properties, foaming, and emulsification is discussed. Despite their prevalent role as functional structures, amyloids also receive a lot of attention due to their association with protein deposition diseases, prompting us to thoroughly investigate the potential health impact of amyloid‐like aggregates in food. A literature review on the effect of the different stages of the human digestive process on amyloid toxicity leads us to conclude that food‐derived amyloid fibrils (even those with potential pathogenic properties) very likely have minimal impact on human health. Nevertheless, prior to wide‐spread application of the technology, it is highly advisable to further verify the lack of toxicity of food‐derived amyloid fibrils.     

Recent development in 3D food printing

Robots and software have been significantly improving our daily lives by rendering us much convenience. And 3D printing is a typical example, for it is going to usher in a new era of localized manufacturing that is actually based on digital fabrication by layer-by-layer deposition in three-dimensional space. In terms of food industry, the revolution that three-dimensional printing technologies is bringing to food manufacturing is convenience of low-cost customized fabrication and even precise nutrition control. This paper is aimed to give a brief introduction of recent development of food printing and material property of food ingredients that can be used to design the 3D food matrix and investigate the relationship between process parameters and resulting printed food properties in order to establish a food manufacturing process with this new food production approach.