Pasteurization Treatment Research Articles

Egg-White Proteins Have a Minor Impact on the Bactericidal Action of Egg White Toward Salmonella Enteritidis at 45°C.

Salmonella enterica serovar Enteritidis is noted for its ability to survive the harsh antibacterial activity of egg white which is presumed to explain its occurrence as the major food-borne pathogen associated with the consumption of eggs and egg products. Liquid egg white is a major ingredient for the food industry but, because of its thermal fragility, pasteurization is performed at the modest temperature of 57°C (for 2–6 min). Unfortunately, such treatment does not lead to sufficient reduction in S. Enteritidis contamination, which is a clear health concern when the product is consumed without cooking. However, egg white is able to limit S. Enteritidis growth due to its alkaline pH, iron deficiency and multiple antimicrobial proteins. This anti-Salmonella activity of egg white is temperature dependent and becomes bactericidal once the incubation temperature exceeds 42°C. This property is exploited in the highly promising pasteurization treatment (42–45°C for 1–5 days) which achieves complete killing of S. Enteritidis. However, the precise mechanism and the role of the egg-white proteins are not fully understood. Here, the impact of exposure of S. Enteritidis to egg white-based media, with or without egg-white proteins (>10 kDa), under bactericidal conditions (45°C) was explored by measuring survival and global expression. Surprisingly, the bactericidal activity of egg white at 45°C was only slightly affected by egg-white proteins indicating that they play a minor role in the bactericidal activity observed. Moreover, egg-white proteins had minimal impact on the global-gene-expression response to egg white such that very similar, major regulatory responses (20% genes affected) were observed both with and without egg-white proteins following incubation for 45 min at 45°C. Egg-white proteins caused a significant change in expression for just 64 genes, including the psp and lysozyme-inhibitor responses genes which is suggestive of an early membrane perturbation effect. Such damage was supported by disruption of the proton motive force by egg-white proteins. In summary, the results suggest that low-mass components of egg white are largely responsible for the bactericidal activity of egg white at 45°C.

Changes in Quality Characteristics of Strawberry Juice After Equivalent High Pressure, Ultrasound, and Pulsed Electric Fields Processes

Understanding the efficacy of viable emerging technologies in preserving overall quality attributes and antioxidant characteristics of fruit juices is of great interest. This study aimed to evaluate the effect of high pressure (HP), ultrasound (US), and pulsed electric fields (PEF) processes on natural microbiota inactivation, as well as changes in physicochemical attributes and phytochemical content of strawberry juice (SJ). HP at 300 MPa (1 min), US at 55 °C (3 min) and 517.1 mW/mL acoustic energy density, and PEF at 35 kV/cm (27 μs) using monopolar square pulses with 2 μs pulse width were applied, and then compared with a conventional thermal pasteurization treatment (72 °C, 15 s). The nonthermal processes were equivalent in terms of Escherichia coli (E. coli) inactivation since the selected processing conditions led to almost identical inactivation level (at least 5-log) of inoculated E. coli. The current study analyzes why these equivalent processes had different effect on SJ quality. All treatments significantly reduced the initial natural microbiota (i.e., total mesophilic aerobic bacteria and yeast-molds) below 2 log CFU/mL. No significant changes were observed on the total soluble solid content (7.83–8.00 °Brix), titratable acidity (0.79–0.84 g/100 mL), and pH (3.45–3.50; except in sonication) between SJ processed samples and the untreated ones (p > 0.05). HPP and PEF significantly promoted higher retention of total phenolic content (TPC) and radical scavenging activity (RSA) than thermal pasteurization, and significantly enhanced total anthocyanin content (TAC) compared with unprocessed SJ. HPP and PEF increased the TPC (4–5%), RSA (18–19%), and TAC (15–17%) in comparison with unprocessed SJ. Multivariate data analysis tools, i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA), were successfully applied for discrimination and classification of SJ samples based on the similarities or differences among physicochemical and phytochemical characteristics. PCA and HCA indicated that HPP- and PEF-treated samples had similar enhanced properties in terms of phytochemical content and were superior to sonicated, thermally pasteurized, and unprocessed samples. The multivariate data analysis methods were very useful to compare and classify SJ quality characteristics as a function of the processing technology. This study demonstrated that the application of the equivalent processing approach may reveal new opportunities to produce equivalent or even enhanced quality fruit juices.

Gliadin Nanoparticles Pickering Emulgels for β-Carotene Delivery: Effect of Particle Concentration on the Stability and Bioaccessibility.

β-carotene is a promising natural active ingredient for optimum human health. However, the insolubility in water, low oral bioavailability, and instability in oxygen, heat, and light are key factors to limit its application as incorporation into functional foods. Therefore, gliadin nanoparticles (GNPs) Pickering emulgels were chosen as food-grade β-carotene delivery systems. The objectives of the present study were to investigate the influence of GNPs concentration on the rheological properties, stability, and simulated gastrointestinal fate of β-carotene of Pickering emulgels. The formulations of Pickering emulgels at low GNPs concentration had better fluidity, whereas at high GNPs concentration, they had stronger gel structures. Furthermore, the thermal stability of β-carotene loaded in Pickering emulgels after two pasteurization treatments was significantly improved with the increase of GNPs concentration. The Pickering emulgels stabilized with higher GNPs concentration could improve the protection and bioaccessibility of β-carotene after different storage conditions. This study demonstrated the tremendous potential of GNPs Pickering emulgels to carry β-carotene.

Microbiological and process variability using biological indicators of inactivation (BIIs) based on Bacillus cereus spores of food and fish-based animal by-products to evaluate microwave heating in a pilot plant

Microwave processing can be a valid alternative to conventional heating for different types of products. It enables a more efficient heat transfer in the food matrix, resulting in higher quality products. However, for many food products a uniform temperature distribution is not possible because of heterogeneities in their physical properties and non-uniformtiy in the electric field pattern. Hence, the effectiveness of microwave inactivation treatments is influenced by both intrinsic (differences between cells) and extrinsic variability (non-uniform temperature). Interpreting the results of the process and considering its impact on microbial inactivation is essential to ensure effective and efficient processing.In this work, we quantified the variability in microbial inactivation attained in a microwave pasteurization treatment with a tunnel configuration at pilot-plant scale. The configuration of the equipment makes it impossible to measure the product temperature during treatment. For that reason, variability in microbial counts was measured using Biological Inactivation Indicators (BIIs) based on spherical particles of alginate inoculated with spores of Bacillus spp. The stability of the BIIs and the uncertainty associated to them was assessed using preliminary experiments in a thermoresistometer. Then, they were introduced in the food product to analyse the microbial inactivation in different points of the products during the microwave treatment. Experiments were made in a vegetable soup and a fish-based animal by-product (F-BP).The results show that the variation in the microbial counts was higher than expected based on the biological variability estimated in the thermoresistometer and the uncertainty of the BIIs. This is due to heterogeneities in the temperature field (measured using a thermographic camera), which were higher in the F-BP than in the vegetable soup. Therefore, for the process studied, extrinsic variability was more relevant than intrinsic variability. The methodology presented in this work can be a valid method to evaluate pasteurization treatments of foods processed by heating, providing valuable information of the microbial inactivation achieved. It can contribute to design microwave processes for different types of products and for product optimization.

Impact of Ohmic Heating and High Pressure Processing on Qualitative Attributes of Ohmic Treated Peach Cubes in Syrup.

Stabilization of ohmic pretreated peach cubes (ohm) in syrup, representative of semifinished fruit products, was finalized by ohmic heating (OHM) and high pressure processing (HPP), proposed respectively as thermal and nonthermal pasteurization, in comparison to a conventional pasteurization treatment (DIM). The samples were then studied in terms of histological, physical (dimensional distribution, tenderometry, texture, viscosity of syrup and colour), chemical (total phenolic and ascorbic acid content), and sensorial (triangle test) properties. Severe modifications of the cell walls were observed in ohm-DIM and ohm-OHM samples, with swelling and electroporation, respectively. From chemical analyses, significant reduction of ascorbic acid and simultaneous increase of total phenolics content were observed for ohm-DIM and ohm-OHM, probably in relation to the cell wall damages. ohm-HPP showed the best preservation of the dimensional characteristics and hardness, followed by ohm-OHM and ohm-DIM. In addition, textural and colour parameters evidenced similar results, with ohm-HPP as the less different from ohm. Finally, the sensorial analysis confirmed ohm-HPP and ohm-OHM samples as the most similar to ohm as well as the most appreciated in terms of colour and consistency.

Influence of seasonal variation and processing on protein glycation and oxidation in regular and hay milk

Climate and feeding influence the composition of bovine milk, which is further affected by thermal treatment inducing oxidation and Maillard reactions. This study aimed to evaluate season- and processing-related changes in the modified proteome of milk from two different feeding systems. Therefore, tryptic digests of regular and hay milk were analyzed by targeting 26 non-enzymatic modifications using LC-MS. Forty-five glycated, 48 advanced glycation endproduct (AGE-) modified, and 20 oxidized/carbonylated peptides representing 44 proteins were identified with lactosylation, formyllysine, and carboxymethyllysine being most common. The numbers and quantities of glycation- and oxidation-related modifications were similar between regular and hay milk and among seasons. The effects of pasteurization and ultra-high temperature (UHT) treatment were comparable for both milk types. In particular UHT treatment increased the numbers of identified modifications and the relative quantities of lactosylated peptides. The number of identified AGE-modified and oxidized residues increased slightly after UHT-treatment, but the contents were stable.

Stability of the Antimicrobial Capacity of Human Milk Against Cronobacter Sakazakii During Handling

Neonatal infections with Cronobacter sakazakii have recently been associated with the consumption of expressed human milk. (1) To evaluate whether human milk has antimicrobial capacity against C. sakazakii and (2) to determine the stability of its capacity when it is subjected to various treatments. The antimicrobial capacity of human milk against C. sakazakii was evaluated using an observational, cross-sectional, comparative design. Mature human milk samples (N = 29) were subjected to different treatments. After incubation at 37°C for 72 hr, samples were compared with fresh milk on the stability of their antimicrobial capacity. Two-way analysis of variance (ANOVA) was performed. In fresh milk, counts of C. sakazakii were reduced by 47.26% (SD = 6.74) compared to controls. In treated milk, reductions were: refrigeration at 4°C for 72 hr (M = 33.84, SD = 13.84), freezing at -20°C for 1, 2, and 3 months (M = 40.31, SD = 9.10; M = 35.96, SD = 9.39; M = 26.20, SD = 13.55, respectively), Holder pasteurization (M = 23.56, SD = 15.61), and human milk bank treatment with (M = 14.37, SD = 18.02) and without bovine fortifier (M = 3.70, SD = 23.83). There were significant differences (p < .05) between fresh and treated milk. Human milk has antimicrobial capacity against C. sakazakii. However, its capacity is negatively influenced by common preservation and hygienization methods. Milk should be stored refrigerated for a maximum of 72 hr or frozen for a short period of time.

Effect of casein/whey ratio on the thermal denaturation of whey proteins and subsequent fouling in a plate heat exchanger

Dairy fouling is a ubiquitous problem in food processing, however, the fouling mechanism is not fully understood and investigations arose mainly from experiments with model systems that contained only whey proteins, typically reconstituted from whey protein isolate powder (WPI). The effect of casein on fouling has been rarely considered despite it is the major component of milk proteins. To fill this gap, whey protein-based model fluids containing different casein concentrations and fixed content of added calcium were prepared, leading to various Casein/WPI mass ratios. The effect of Casein/WPI on β-lactoglobulin (BLG) denaturation at molecular level and subsequent fouling behavior in the pilot-scale plate heat exchanger during pasteurization treatment was investigated. It was shown that Casein/WPI significantly affects the fouling behavior: at low Casein/WPI, fouling mass dropped dramatically until a minimum value was reached located at Casein/WPI of 0.2. While at higher Casein/WPI, fouling mass increased with elevated Casein/WPI. Element mapping of the fouling layer also reveals that different structures and fouling mechanisms occur depending on Casein/WPI ratio. Finally, it was established that contrary to WPI solutions, BLG thermal denaturation is poorly correlated to decrease/extent of fouling for casein protein-based solutions showing that the presence of casein deeply modifies mineral and protein interactions and fouling build-up.

Impact of high-pressure and microwave-assisted thermal pasteurization on inactivation of Listeria innocua and quality attributes of green beans

In response to the increasing consumer demand for high-quality, minimally processed ready-to-eat (RTE) meals, the food industry has shown strong interests in exploring new processing technologies for production of safe RTE meals with an adequate shelf life in cold distribution chains. The purpose of this research was to understand the effect of high-pressure processing (HPP) and microwave-assisted thermal pasteurization on the quality attributes of green beans.The pasteurization conditions were selected as 600 MPa at 25 °C for 10 min for HPP and 70 °C for 2 min for processing with microwave-assisted pasteurization system (MAPS). Survival of L.innocua ATCC 51742 in green bean brine solution was analyzed right after the pasteurization processes. The quality attributes of the green beans, such as color, chlorophyll content, texture, vitamin C content, and pH, were further determined during storage at 2 °C for 36 days and 10 °C for 20 days.High-pressure treatment resulted in a 3.7-log CFU/g reduction in L. innocua ATCC 51742, whereas MAPS processing showed a 9.0-log CFU/g reduction. Both pasteurization processes provided significantly better green color retention when the beans were stored at 2 °C than when they were stored at 10 °C. Regardless of the pasteurization methods, the change in the greenness (a*) value of the beans followed similar trends during storage. Both methods caused an increase in the total color difference (ΔE) and a decrease in hue angle (yellowness) during storage (p < 0.05), but they had no significant effect on firmness, total chlorophyll content, and pH of the green beans. After the pasteurization processes, the vitamin C content of the HPP-treated green beans decreased significantly in comparison with the MAPS-treated beans (p < 0.05). This work reveals that both pasteurization treatments have a similar impact on quality attributes of green beans and that MAPS processing is more efficient in inactivating L. innocua ATCC 51742.

Influence of Pasteurization on the Quality of Pineapple, Watermelon and Banana Pulps-based Smoothie Flavoured with Coconut Milk

Effect of pasteurization on the quality of pineapple, watermelon and banana pulps-based smoothie flavoured with coconut milk was reported. The fruits were sorted, washed thoroughly with clean salt water, peeled, sliced and diced into small cubes, while coconut heads were processed into milk. Smoothies from blends of pineapple (P), watermelon (W) and banana (B) pulps were formulated and coconut milk (C) was added as a flavourant. The blends: PWBC1 (50:40:10:10), PWBC2 (50:10:40:10) and PWBC3 (50:30:20:10), were of different ratios with each pasteurized to obtain three more samples (A1, A2 and A3). The three non-pasteurized products served as control. Chemical, microbial and sensory analyses were carried out on all smoothie samples. Significant (p>0.05) differences did not exist in proximate composition between treatments; but within samples, moisture (65.15-73.68%), crude protein (0.45-1.08%), fat (3.04-3.34%), fibre (6.82-10.14%), ash (1.50-2.80%) and carbohydrate (14.21-18.79%) contents. All the samples had significantly (p-1), pro-vitamin A (63.64-250.72 mg 100ml-1), potassium (98.73-200.59 mg 100ml-1) and calcium (17.79-19.10 mg 100ml-1) contents. Pasteurization treatment gave smoothies of comparable nutritional and organoleptic properties with the conventional non-pasteurized smoothies. The pasteurized samples (A2 and A3) had higher scores in overall acceptability for the sensory attributes. With pasteurization, safe smoothie beverages prepared and consumed regularly can assist in the enhancement and sustainability of household food and nutrition security.

Survival of Tick-Borne Encephalitis Virus in Goat Cheese and Milk.

Survival of tick-borne encephalitis virus was studied from pasteurized and unpasteurized goat milk and from salted/unsalted and spiced/unspiced cheese made from goat milk inoculated with low and high litres of infective virus. Both soft (63°C, 30min) and fast (72°C, 15s) pasteurization conditions destroyed viable virus particles. A small amount of infective virus could be detected only for 5‒10days from milk, and from unsalted cheese. From milk inoculated with a higher amount of virus, infectious viral particles were detectable for 20‒25days and from unsalted cheese samples for 10‒15days, independently of the use of spices. Pasteurization and salt treatment made goat milk and cheese safely consumable. These two methods must be used when making any human food from goat milk to avoid milk-borne human TBEV infections.

Comparative study on quality of whole milk processed by high hydrostatic pressure or thermal pasteurization treatment

Quality of whole milk pasteurized by high hydrostatic pressure processing (HPP: 600 MPa for 5 min) or HPP combined with microfiltration (MF + HPP) were compared with two conventional heat treatments, low temperature long time (LTLT: 63 °C for 30 min) and high temperature short time (HTST: 72 °C for 15 s). Inactivation of microorganisms, changes in volatiles, protein denaturation, gastric digestion, and sensory quality were evaluated after 8 days of storage at 5 °C. Total bacterial and E.coli counts were reduced to approximately the same level for both high pressure and heat treated milks. The denaturation of β-lactoglobulin was significantly higher for high-pressurized milks, while no significant differences were found in gastric in-vitro protein digestion compared with heat treated milks. The results of volatile compounds revealed that HTST and HPP-treated milks exhibited very similar aroma profiles, while LTLT-milks were characterized by higher levels of ketones. After 8 days storage, the sensory analysis showed that LTLT milk was the one that differed most from the other three milks with highest intensities of all the sensory attributes, while no tangible differences were found between HTST and any HPP and MF + HPP milk, except for Boiled Taste that was slightly but significantly lower for MF + HPP.

An Overview of Effects Induced by Pasteurization and High-Power Ultrasound Treatment on the Quality of Red Grape Juice.

In juice processing, ultrasound treatment has been tested as a potential alternative to conventional thermal methods to inactivate microorganisms and to enhance the nutritional status of juice. In this study, the impact of pasteurization and high-power ultrasound treatment on the quality of red grape juice was investigated in terms of the content of bioactive compounds such as phenolic compounds and l-ascorbic acid as well as regarding the microbiological and physicochemical properties. The grape juice was subjected to pasteurization (80 °C, 2 min) as well as to ultrasound treatment with an amplitude of 50 and 70% for 5 and 10 min. The results indicated the same level of total phenolic content for pasteurized and sonicated samples for 10 min with an amplitude of 70%, while the highest level of l-ascorbic acid was recorded for sonicated samples with an amplitude of 70% for 10 min. pH of sonicated samples decreased with amplitude and treatment time while total soluble solids and titratable acidity increased with amplitude and time. Moreover, the results indicated the usefulness of juice sonication to enhance the inactivation of microorganisms. Thus, the high-power ultrasound treatment might represent a viable technique to replace the conventional thermal treatment in grape juice processing.

Essential oil-loaded nanostructured lipid carriers: The effects of liquid lipid type on the physicochemical properties in beverage models

Nanostructured lipid carriers (NLC) can be used in the development of new functional foods. Cinnamon essential oil (CEO)-loaded NLC were prepared using different liquid edible oils (corn, sesamol, sweet almond, and black seed oil), a solid lipid (cocoa butter) and a surfactant (Tween 80). The average size and the encapsulation efficiency of CEO-NLC were in the range of 100 ± 1 - 120 ± 10 nm and more than 82.1 ± 0.03%, respectively, while the optimum results were obtained for the almond oil-based NLC. The zeta potentials of different formulation were -14.9 ± 0.1 to -17.5 ± 0.04 mV. The physicochemical stability of CEO-NLC was evaluated during 40 days with different pH conditions (i.e., pH of milk at 6.8 and some fruit juices at 3.8) and pasteurization treatment. Both particle size and the encapsulation stability slightly changed with different pH conditions and pasteurization treatment. The almond oil-based NLC showed promising properties for increasing the protection and stability of CEO with different conditions of food beverages.

Phenotypic Diversity of Lactobacillus casei Group Isolates as a Selection Criterion for Use as Secondary Adjunct Starters.

Autochthonous lactic acid bacteria (LAB) play a key role in the development of cheese flavor. As the pasteurization treatment on raw milk causes the elimination of LAB, secondary starter cultures are used in cheese manufacture to obtain cheeses with improved and standardized flavors. In this work, strains of the L. casei group isolated from traditional Italian cheeses were screened for their phenotypic features of technological interest for use as secondary starters. Their milk acidifying performance and the production of volatile compounds when grown in milk were evaluated. Simultaneously, the acetoin metabolic pathway presence was screened in the strains and assessed for its transcriptional activation. The results showed that the analyzed strains, despite belonging to taxonomically-related species, vary greatly according to the measured phenotypes. Four strains among the fourteen screened could be potentially used as adjunct cultures for cheese-making processes. The strain that showed the highest production of acetoin upregulated the aspartate pathway. An increased knowledge of volatile compounds’ production and acidifying properties of LAB strains isolated from traditional dairy products might guide the selection of strains for industrial applications.

Physical properties and storage stability of reverse osmosis skim milk concentrates: Effects of skim milk pasteurisation, solid content and thermal treatment

Concentrated dairy products are of increasing interest within the dairy industry. Skim milk concentrates can be produced by reverse osmosis membrane filtration, which can be considered a non-thermal process. Therefore, the physical properties of concentrates differ from the properties of concentrates produced by evaporation. In this study, reverse osmosis filtration of raw and pasteurised skim milk was carried out in batch up to 28% total solids content and the effect of thermal treatment (65–110 °C, 15 s) and storage at 5 °C up to ten days on rheological and physical properties of concentrates, were evaluated. Concentrates produced from pasteurised skim milk required longer concentration times and showed larger average casein micelle sizes, but limited structure build-up capability during storage compared to concentrates produced from raw milk which more readily created structural networks between the milk constituents and consequently had higher viscosity. Thermal treatment of concentrates increased their average particle size and viscosity, an effect enhanced by increasing the total solids content. Concentrates produced from non-pasteurised milk showed the strongest shear-thinning behaviour during storage. Thus, the thermal treatment of milk before or after the concentration process, controls the structure formation of skim milk concentrates during storage.

Augmenting the Pressure-Based Pasteurization of Listeria monocytogenes by Synergism with Nisin and Mild Heat.

The current study investigated Listeria monocytogenes inactivation using mild heat with elevated hydrostatic pressure and nisin under buffered condition. A four-strain pathogen mixture was exposed to 0 (control) and up to 9 min of (1) 4 °C elevated pressure; (2) 4 °C elevated pressure and nisin; (3) 4 °C nisin; (4) heat at 40 °C; (5) 40 °C elevated pressure; (6) 40 °C elevated pressure and nisin; and (7) 40 °C nisin. Elevated hydrostatic pressure at 400 MPa (Hub880 Explorer, Pressure BioScience Inc., Easton, MA, USA) and nisin concentration of 5000 IU/mL were used in the trials. Analyses of variance were conducted, followed by Dunnett’s- and Tukey-adjusted means separations. Under conditions of these experiments, nisin augmented (p < 0.05) decontamination efficacy of 40 °C heat and elevated hydrostatic pressure treatments, particularly at treatment interval of 3 min. This synergism with nisin faded away (p ≥ 0.05) as the treatment time for thermal, high-pressure, and thermal-assisted pressure processing increased. The results of our study, thus, exhibit that practitioners and stakeholders of pressure-based technologies could benefit from synergism of mild heat and nisin for short-term, high-pressure pasteurization treatments to achieve microbial safety and economic feasibility comparable to traditional heat-treated products.

Effect of HTST Thermal Treatments on End-Use Quality Characteristics of Goat Milk.

Goat milk samples were pasteurized at high-temperature (72°C, 75°C, and 81°C) and in short-time (15 s and 25 s) combinations. Physical, chemical and microbial qualities of the pasteurized milk samples were evaluated 0, 2, 3, and 4 weeks of storage at 4°C. Despite the different thermal treatments, specific-gravity and viscosity were comparatively stable immediately after pasteurization (IAP). The viscosity of pasteurized milk at 81°C showed significant increase (P < 0.05) from 1.58 ± 0.18 to 2.30 ± 0.15 mPa s during four weeks of storage. Relative lightness “L” value decreased by about 10% during the storage period of 81°C pasteurization samples. Acidity increased with heat treatment irrespective of holding time, but in 81°C pasteurized sample higher acidity was developed at end of the storage. Fat oxidation 2-3 times higher at 81°C than 72°C pasteurized samples. Total protein (TP%) and nonprotein nitrogen contents were stable IAP but TP reduced significantly (P < 0.05) at two weeks storage. The whey protein denaturation increased with pasteurization treatments and storage time. Antioxidant activity of raw goat milk was 34.8 ± 5.01 μmol l−1 and was decreased by 20–43% IAP compared to raw milk samples, but gradually increased during storage. IAP, mesophilic counts were in the range of 980–110 cfu ml−1 (72°C/15–81°C/25 s) and increased from 2236 to 680 cfu ml−1 samples stored at 4 weeks. Results showed that best quality stability of pasteurized goat milk achieved by heat treatments between 72°C/25 s and 75°C/25 s heat treatments up to 3 weeks of storage under 4°C.

Effects of ohmic heating on technological properties of whole egg

Abstract The aim of this work was to study the effects of different ohmic heating conditions on color, rheology, foaming, and gelling properties of whole egg. Industrial products treated by conventional heat pasteurization and the corresponding raw materials were also evaluated. Ohmic treatments accomplished in a static cell (65.5 °C × 3 min, 70 °C × 1 min, and 67 °C × 4.5 min) increased whole egg apparent viscosity (up to 190%), but also foam overrun (up to 28%) and gel hardness (up to 15%). The performance improvement was confirmed by treatments carried out in a continuous pilot plant (71 °C × 0.6 min, 68 °C × 1.4 min) and the products resulted stable during storage at 4 °C for 30 days. In conclusion, this study demonstrated that ohmic heating is a suitable alternative to conventional pasteurization. Low temperature treatments are preferable to avoid possible rheological issues due to protein denaturation. Industrial relevance Whole egg is a protein ingredient with multiple technological properties, used in many foods. Due to safety reasons, food manufacturers often use pasteurized liquid egg products, microbiologically safer and easier to handle with respect to shell eggs. In order to satisfy the required sanitary levels for liquid egg products, thermal pasteurization treatments are needed. However, since egg proteins are very sensitive to high temperatures, attention must be paid to avoid coagulation entailing deleterious effects against egg quality. In this study, different ohmic heating treatments were evaluated as milder alternatives to conventional pasteurization. The lab- and pilot-scale experiments and the subsequent statistical analyses of the obtained results contributed to assess the effects of the different ohmic treatments on technological features (e.g. color, rheology, foaming, and gelling properties) of liquid whole egg. This study demonstrated that ohmic heating is a suitable technology for whole egg treatment, paving the way for new opportunities in order to produce safe food ingredients with improved technological functionalities.

Functional quality of optimized peach-based beverage developed by application of ultrasonic processing.

The influence of thermal treatment (at 90°C for 10 min) and sonication (at 20 kHz and 130 W for 30, 60, and 90 min on room temperature) on the physicochemical properties, bioactive compounds, antioxidant activity, and organic acids of fresh formulated functional peach beverage was investigated. The results indicated that conventional pasteurization and sonication treatment did not show any significant changes in pH value and Brix amount of juice, and however, a rise in cloud value was observed under all processing conditions. The thermal treatment caused the decrement in total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (assessed by diphenyl dipicryl hydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP) and 2,2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS)), and organic acids of juice, whereas sonication treatment for 90 min increased maximum the activity of bioactive compounds (TPC: 600.61 µg/100 ml; TFC: 177 µg CE/100 ml), antioxidants (DPPH: 51.87%; FRAP: 506.13 µmol Trolox/L; ABTS: 1,507.375 µmol Trolox/L), and organic acids (malic acid: 998; citric acid: 128; oxalic acid: 145; shikimic acid: 63 µg/100 ml) as compared to other treatment conditions and control. Multivariate data analysis was done by principal component analysis as it identifies patterns in data by comparing data sets which is further expressed based on their similarities and discriminations, respectively.