Comparative thermal impact of two UHT technologies, continuous ohmic heating and direct steam injection, on the nutritional properties of liquid infant formula

A mini-review about direct steam heating and its application in dairy and plant protein processing

The world's requirement for plant protein consumption is increasing. However, their application in different foods is limited due to their low techno-functionality. Heating is the most widely used method to improve the functionality of proteins. Compared to indirect tubular or plate heating methods, direct steam injection heating (DSIH) can heat the sample much faster, thus modifying the structure and functionality of protein differently. It is used in the sterilization of milk to minimize the heat-induced denaturation of whey proteins and the loss of volatiles. By contrast, its application in producing plant protein ingredients is seldom. This review summarizes recent research using DSIH to process dairy- and plant-based proteins and proposes future research perspectives. DSIH is a promising technique for producing functional protein ingredients. It is of particular interest to overcome the techno-functional hurdles of plant protein blends using DSIH to improve their behavior in different food matrices.

Novel Approaches to Environmental Monitoring and Control of Listeria monocytogenes in Food Production Facilities

Listeria monocytogenes is a serious public health hazard responsible for the foodborne illness listeriosis. L. monocytogenes is ubiquitous in nature and can become established in food production facilities, resulting in the contamination of a variety of food products, especially ready-to-eat foods. Effective and risk-based environmental monitoring programs and control strategies are essential to eliminate L. monocytogenes in food production environments. Key elements of the environmental monitoring program include (i) identifying the sources and prevalence of L. monocytogenes in the production environment, (ii) verifying the effectiveness of control measures to eliminate L. monocytogenes, and (iii) identifying the areas and activities to improve control. The design and implementation of the environmental monitoring program are complex, and several different approaches have emerged for sampling and detecting Listeria monocytogenes in food facilities. Traditional detection methods involve culture methods, followed by confirmation methods based on phenotypic, biochemical, and immunological characterization. These methods are laborious and time-consuming as they require at least 2 to 3 days to obtain results. Consequently, several novel detection approaches are gaining importance due to their rapidness, sensitivity, specificity, and high throughput. This paper comprehensively reviews environmental monitoring programs and novel approaches for detection based on molecular methods, immunological methods, biosensors, spectroscopic methods, microfluidic systems, and phage-based methods. Consumers have now become more interested in buying food products that are minimally processed, free of additives, shelf-stable, and have a better nutritional and sensory value. As a result, several novel control strategies have received much attention for their less adverse impact on the organoleptic properties of food and improved consumer acceptability. This paper reviews recent developments in control strategies by categorizing them into thermal, non-thermal, biocontrol, natural, and chemical methods, emphasizing the hurdle concept that involves a combination of different strategies to show synergistic impact to control L. monocytogenes in food production environments.

Formation of advanced glycation end products by novel food processing technologies: A review

Advanced glycation end products (AGEs) are a diverse group of compounds formed endogenously and exogenously due to non-enzymatic glycation of proteins and lipids. Although the effects of heating on AGE concentrations in foods are known, few studies have been published addressing the effects of new processing technologies on AGE formation. This work focuses on the current scientific knowledge about the impacts of novel technologies on AGE formation in food products. Most studies do not measure AGE content directly, evaluating only products of the Maillard reaction. Moreover, these studies do not compare distinct operational conditions associated with novel technologies. This lack of information impacts negatively the establishment of process-composition relationships for foods with safe AGE dietary intakes. Overall, the outcomes of this review suggest that the use of novel technologies is a promising alternative to produce food products with a lower AGE content.

Quantitation of furosine, furfurals, and advanced glycation end products in milk treated with pasteurization and sterilization methods applicable in China

Pasteurization and sterilization, normally carried out in milk, can induce the Maillard reaction, which can produce substances that are harmful to health. Quantitation of initial, intermediate, and advanced Maillard reaction products in milk was conducted for pasteurization (low-temperature long-time [LTLT], high-temperature short-time [HTST]) and sterilization (ultra-high temperature [UHT], in-bottle sterilization [BS]) methods. Total lysine and lactose decreased by 32.8% and 6.7% in BS milk, respectively. The generation of furosine in sterilized milk and pasteurized milk ranged from 2.5- to 5.0-fold and 1.4- to 2.8-fold higher, respectively, than those in raw milk. 5-(Hydroxymethyl)furfural increased by 4.7- and 8.4-fold in UHT and BS milk, and 2-furaldehyde (F) was not quantified in raw and LTLT milk. The concentrations of Nε-(carboxymethyl)lysine (CML) was nearly 4.4- to 6.7-fold higher than that of Nε-(carboxyethyl)lysine in the heated milk samples. CML in UHT and BS milk were around 1.4-fold and 1.6-fold higher than that in raw milk, respectively. The concentration of these Maillard reaction products in sterilized milk was significantly higher than those in raw, LTLT, and HTST milk. The results of this study could improve safety control in the dairy industry with respect to pasteurization and sterilization procedures.

Production of grape pekmez by Ohmic heating-assisted vacuum evaporation

Pekmez is a concentrated syrup-like food conventionally produced by vacuum evaporation process from sugar-rich fruits. In this study, the applicability of grape pekmez production by ohmic heating assisted vacuum evaporation (ΩVE) method was investigated. Conventional vacuum evaporation (CVE) and ΩVE methods were compared in terms of physicochemical properties, HMF (5-hydroxymethylfurfural) contents, rheological properties, and energy consumptions. ΩVE was run at four different voltage gradients (17.5, 20, 22.5, and 25 V/cm). Total process times for grape pekmez production were determined as 57, 28.5, 32, 39, and 50 minutes for CVE, ΩVE (25 V/cm), ΩVE (22.5 V/cm), ΩVE (20 V/cm) and ΩVE (17.5 V/cm), respectively. Energy consumption of CVE method was higher than ΩVE method for all voltage gradients. Energy efficiency increased as the voltage gradient increased. There was no significant difference between CVE and ΩVE methods for HMF contents. The results show that the ΩVE method could be an alternative to the CVE process for grape pekmez production.

Ohmic heating increases inactivation and morphological changes of Salmonella sp. and the formation of bioactive compounds in infant formula

The effect of ohmic heating (OH) (50, 55, and 60 °C, 6 V/cm) on the inactivation kinetics (Weibull model) and morphological changes (scanning electron microscopy and flow cytometry) of Salmonella spp. in infant formula (IF) was evaluated. In addition, thermal load indicators (hydroxymethylfurfural and whey protein nitrogen index, HMF, and WPNI) and bioactive compounds (DPPH, total phenolics, ACE, α-amylase, and α-glucosidase inhibitory activities) were also studied. OH presented a more intense inactivation rate than conventional heating, resulting in a reduction of about 5 log CFU per mL at 60 °C in only 2.91 min, being also noted a greater cell membrane deformation, higher formation of bioactive compounds, and lower values for the thermal load parameters. Overall, OH contributed to retaining the nutritional value and improve food safety in IF processing.

Electric field effects on proteins - Novel perspectives on food and potential health implications

Electric fields (EF) technologies have been establishing a solid position in emergent food processing and have seen as serious alternatives to traditional thermal processing. During the last decades, research has been devoted to elucidation of technological and safety issues but also fundamental aspects related with interaction of electric fields (EF) with important macromolecules, such as proteins. Proteins are building blocks for the development of functional networks that can encompass health benefits (i.e. nutritional and bioactive properties) but may be also linked with adverse effects such as neurodegenerative diseases (amyloid fibrils) and immunological responses. The biological function of a protein depends on its tridimensional structure/conformation, and latest research evidences that EF can promote disturbances on protein conformation, change their unfolding mechanisms, aggregation and interaction patterns. This review aims at bringing together these recent findings as well as providing novel perspectives about how EF can shape the behavior of proteins towards the development of innovative foods, aiming at consumers' health and wellbeing.

Dulce de leche submitted to ohmic heating treatment: Consumer sensory profile using preferred attribute elicitation (PAE) and temporal check-all-that-apply (TCATA)

This study aimed to evaluate the effects of the application of ohmic heating (OH) to milk (0, 2, 4, 6, 8, or 10 V cm^-1, 72-75 °C/15 s) on the sensory profiling of dulce de leche (DL) evaluated using preferred attribute elicitation (PAE) and temporal Check-all-that-apply (TCATA) methodologies. In addition a consumer test was also performed. OH-DL samples presented increased scores for all the sensory attributes evaluated. Low or intermediate strength electric fields contributed to increase bitter taste and decrease DL aroma and sweet taste of the products, without impact on the overall liking. When high strength electric fields were applied, higher brightness, fluidity and DL flavor scores were observed, as well as, lower intensities in consistency and sandiness scores, resulting in increased acceptance by consumers. From TCATA data, it could be observed that the perception of all sensory attributes increased as well as increased the strength of the electric fields. Overall, the adoption of electric fields with higher strength in ohmic heating during DL processing is advised, since they improved the intensity and perception of desirable intrinsic DL sensory attributes as well as improved DL overall liking.

Electric Field Processing: Novel Perspectives on Allergenicity of Milk Proteins

Milk proteins are being widely used in formulated foods as a result of their excellent technological, functional, and biological properties. However, the most representative proteins from casein and whey fractions are also recognized as major allergens and responsible for the prevalence of cow's milk protein allergy in childhood. Electroheating technologies based on thermal processing of food as a result of application of moderate electric fields, also known by ohmic heating (OH) or Joule effect, are establishing a solid foothold in the food industry. Currently, the influence of OH on allergenic aspects of milk proteins is under debate but still undisclosed. The occurrence of electrical effects on the protein structure and its function has already been reported; thus, the impact of OH over allergenicity should not be overlooked. On the basis of these recent findings, it is then relevant to speculate about the impact of this emergent technology on the potential allergenicity of milk proteins.

Anodic Oxidative Modification of Egg White for Heat Treatment

A new functionalization of egg white was achieved by an electrochemical reaction. The method involves electron transfer from thiol groups of egg white protein to form disulfide bonds. The oxidized egg white produced less hydrogen sulfide during heat treatment; with sufficient application of electricity, almost no hydrogen sulfide was produced. In addition, gels formed by heating electrochemically oxidized egg white exhibited unique properties, such as a lower gelation temperature and a softened texture, presumably due to protein aggregation and electrochemically mediated intramolecular disulfide bond formation.