Retort Sterilization Research Articles

Computer-based monitoring system of retort processes for energy efficiency and carbon emission reduction

Retort sterilization is critical in the food industry. However, retorts are not smart enough to fully monitor and calculate their energy usage to reduce their carbon emissions. In this project, sensors and network equipment were installed in a retort, and a PC-based system was used to process the collected data. To monitor the sterilization status and energy consumption, we added flow sensors and electricity meters and built a visual identification system. Carbon emissions were calculated, and energy conservation and carbon emission reduction strategies were explored. According to the monitoring data, the electricity consumption of the air compressor, boiler, and natural gas combustion accounted for 80 % of the total carbon emissions. If the equipment cannot be changed, the cooling water system can be stopped in noncooling stages to conserve energy. This strategy reduced the energy consumption of the cooling system by 70 % and was the most effective strategy for this project.

Comparative study on microbiological, physicochemical and nutritional properties of whole cow milk by thermal and non-thermal processing technologies

The majority of the bioactive components in milk exhibit sensitivity to heat treatments. This research is the first systematically compare the effects of thermal (low-temperature long time pasteurization, LTLT; high-temperature short time pasteurization, HTST; ultra-high temperature, UHT; microwave-assisted heating; retort sterilization) and non-thermal (ultraviolet-C, UV-C; high hydrostatic pressure processing, HPP; filtered sterilization; high-intensity ultrasound, HIUS) treatments on the physicochemical properties and immune-active serum proteins of whole milk aliquots under the equivalent microbicidal efficacy. LTLT and HTST had little impact on whole milk. HPP at 400 MPa for 5 min was an optimal alternative to pasteurized milk in terms of equivalent microbicidal efficacy, higher nutrient retention (∼6% and 16.2% loss for IgG and lactoferrin) and fewer oxidation products (0.69 nmol/mg protein carbonyls). The serum protein denaturation of 600 MPa HPP-treated milk (79.4% and 31.36% loss for IgG and lactoferrin) was significantly higher than in pasteurized milk, but still lower than in UHT milk (97.16% and 70.85% loss for IgG and lactoferrin). Since photo-oxidation induced by high-dose irradiation was detrimental to the organoleptic properties, relying on UV-C as stand-alone replacement to pasteurization is not advisable. Combined with existing pasteurization methods, UV-C can achieve superior microbial inactivation at mild sterilization temperatures. HIUS, a promising novel tool, should be further optimized regarding the relevant standards to enable it to be used in industrial-scale processing and reproducibility. Compared with traditional thermal treatments, non-thermal strategies offer a significant reduction in the microbial load of raw milk while better preserving bioactive proteins, However, optimizing processing parameters remains essential to strike a balance between microbial inactivation and retention of active substances.

Unlocking the Potential of Microwave Sterilization Technology in Ready-to-Eat Imitation Crab Meat Production.

Microwave sterilization is a novel potential sterilization technology to improve food quality. An industrial microwave sterilization system was used to sterilize imitation crab meat under thermal processing intensity F0 = 1, 2, 3. The characteristics of the microwave process, such as heating rate, processing time, and C100, were calculated. In addition, the quality of processed imitation crab meat was investigated. Compared with the conventional retort method, microwave sterilization significantly shortened the processing time of imitation crab meat by 63.71% to 72.45%. Under the same thermal processing intensity, microwave sterilization has demonstrated better results than retort sterilization in terms of water-holding capacity, color, and texture. Furthermore, microwave-treated imitation crab meat ingredients had a greater capacity to bind water molecules and obtained a more appropriate secondary protein structure. In addition, microwave technology can better preserve the unsaturated fatty acids (UFA) of imitation crab meat, which are 9.14%, 1.19%, and 0.32% higher than the traditional method at F0 = 1, 2, 3. The results would provide useful data for the subsequent research and development of ready-to-eat surimi products.

Heat penetration and quality attributes of superheated steam sterilization (SHS) home meal replacement (HMR) meat products stew

Retort sterilization (RTS) is essential for the production of shelf-stable home meal replacement (HMR)-type Korean foods. However, the thermal abuse caused by excessive retort processing can result in quality degradation. Short processing times can minimize quality degradation and nutritional loss during sterilization. The potential of superheated steam sterilization (SHS) for producing shelf-stable HMR was investigated. The effect of SHS at 140 °C on HMR meat products stew was compared with that of RTS. SHS allowed a rapid temperature increase in the sausages and spam. In the sterilization equivalence of sausage, SHS at 140 °C and 1 s showed the F0 value of 34.7 ± 5.9 which could sufficiently satisfy the microbial safety standard of F0 values at 7–10 min. Thermal doses of SHS treated sausage was 97 ± 9 k°C·s which has lesser values (119 ± 9 k°C·s) than that of RTS. The sausage hardness after SHS was 107.7 ± 13.3 N, which has lower thermal degradation than the 78.9 ± 7.1 N observed after RTS. This study demonstrates the potential of SHS treatment for maintaining the quality of sterilized HMR products.

Physicochemical and sensory properties of retort chicken curry mousse fortified with branched-chain amino acids for the elderly

Although retort sterilization is effective in high-temperature sterilization of special nutritional products, its effect on sensorial and nutritional properties after sterilization has not been proven. The purpose of this study was to develop a BCAAs fortified chicken curry mousse (CCM) for the elderly that is easy to chew, swallow, and convenient to cook and consume at home. Additionally, it was to investigate the effect of retort processing on the sensory satisfaction and nutritional formula of the products. A viscosity thickener was added to set the thickener concentration based on the fork drip test of the International Dysphagia Diet Standardization Initiative. CCM was retort-treated at 121 °C for 30 min to evaluate its physicochemical (color, viscosity, rheology, texture, syneresis, pH, and amino acid analysis) and sensory properties. The viscosity decreased and texture changed smoothly after retorting, and the color became darker. The syneresis and pH of the retorted mousse showed fewer changes than the non-retorted during 12 days. Retorted products were increased the BCAAs, and scored high in overall acceptance in the sensory evaluation. Therefore, the BCAAs-enriched retort CCM developed in this study is expected to hedonically appeal to the elderly as well as benefitting their muscle health and nutrition.

Effect of vat pasteurization, ultra-high temperature sterilization, retort sterilization and homogenization on soluble proteins in donor human milk detected via proteomics

Donor human milk (DHM) is recommended for preterm infants when a parent's own milk is unavailable or insufficient. To ensure microbiological safety, DHM is processed by donor milk processing companies using vat pasteurization (Vat-PT), ultra-high temperature (UHT) sterilization or retort (RTR) sterilization with and without homogenization. These processes may differentially affect the bioactive proteins in DHM. LC-MS/MS-based proteomics was applied to compare the detection of proteins in the soluble fraction of DHM after Vat-PT, UHT sterilization, RTR sterilization and homogenization in comparison with raw DHM (referred to herein as intact protein survival or retention). Protein retention (based on protein counts and abundances) was higher after Vat-PT than after UHT, and retention was higher after UHT sterilization than after RTR sterilization. Homogenization further decreased protein retention (based on protein counts and abundances) in both UHT- and RTR-treated samples. Representative DHM proteins including lactoferrin, lysozyme, immunoglobulins and caseins had higher retention after Vat-PT (5–57% decrease) than UHT (25–82% decrease) and RTR (54–88% decrease) treatments. These results will guide DHM processing to preserve bioactive proteins and potentially improve infant outcomes.

Using Numerical Analysis to Develop a Retort Process to Enhance Antioxidant Activity and Physicochemical Properties of White Radish (Raphanus sativus L.) in Different-Sized Packages

Thermal processing of white radish using retort sterilization at different temperatures was investigated according to the dimension of the package. Four different samples with the same weight and volume were placed in packages with different dimensions. The degree of sterilization (i.e., F0-value) at the cold point targeted at 6 min was determined based on experimental data and heat transfer simulation. The sterilization time was considerably increased with a decrease in surface area to unit volume ratio (φ) at each temperature. The sterilization time for the sample with the highest φ (155.56) was approximately five times faster than the sample with the lowest φ (72.22) at all heating temperatures. Numerical simulation conducted with a proper heat transfer coefficient (h) showed mostly good agreement with the experimental data (RMSE < 2 °C). Changes in color and total phenolic content were higher for samples heated at higher temperatures. Hardness values of white radish samples measured for center and edge parts separately were more uniform for samples with a high φ. Results in this study suggest that optimizing heating conditions of root vegetables must consider their package dimensions to satisfy quality attributes after sterilization. Numerical simulation can be utilized as a useful tool to design the sterilization process.

Structural and functional changes of bioactive proteins in donor human milk treated by vat-pasteurization, retort sterilization, ultra-high-temperature sterilization, freeze-thawing and homogenization.

BackgroundDonor human milk should be processed to guarantee microbiological safety prior to infant feeding, but this process can influence the structure and quantity of functional proteins.ObjectiveThe aim of this study was to determine the effect of thawing, homogenization, vat-pasteurization (Vat-PT), retort sterilization (RTR) and ultra-high-temperature (UHT) processing on the structure of bioactive proteins in donor milk.MethodsPooled donor milk was either not treated (Raw) or treated with an additional freeze-thaw cycle with and without homogenization, Vat-PT, RTR with and without homogenization, and UHT processing with and without homogenization. Overall protein retention was assessed via sodium-dodecyl sulfate (SDS-PAGE), and the immunoreactivity of 13 bioactive proteins were assessed via enzyme-linked immunosorbent assay (ELISA).ResultsFreeze-thawing, freeze-thawing plus homogenization and Vat-PT preserved all the immunoglobulins (sIgA/IgA, IgG, IgM) in donor milk, whereas RTR and UHT degraded almost all immunoglobulins. UHT did not alter osteopontin immunoreactivity, but Vat-PT and retort decreased it by ~50 and 70%, respectively. Freeze-thawing with homogenization, Vat-PT and UHT reduced lactoferrin's immunoreactivity by 35, 65, and 84%, respectively. Lysozyme survived unaltered throughout all processing conditions. In contrast, elastase immunoreactivity was decreased by all methods except freeze-thawing. Freeze-thawing, freeze-thawing plus homogenization and Vat-PT did not alter polymeric immunoglobulin receptor (PIGR) immunoreactivity, but RTR, RTR plus homogenization and UHT increased detection. All heat processing methods increased α-lactalbumin immunoreactivity. Vat-PT preserved all the growth factors (vascular/endothelial growth factor, and transforming growth factors β1 and β2), and UHT treatments preserved the majority of these factors.ConclusionDifferent bioactive proteins have different sensitivity to the treatments tested. Overall, Vat-PT preserved more of the bioactive proteins compared with UHT or RTR. Therefore, human milk processors should consider the impact of processing methods on key bioactive proteins in human milk.

Loss of Eicosapentaenoic Acid (EPA) after Retort Sterilization of the EPA-BCAA Fortified Complete Nutrition Drink

Retort sterilization is cost-effective for small-scale production of specialized nutrition products. However, the sensory properties and stability of active ingredients after sterilization remain undetermined. This study aimed to investigate the effect of retort on the existence of functional compounds and the sensory satisfaction of a fortified complete nutrition formula with branched-chain amino acids (BCAAs), and fish oil providing eicosapentaenoic acid (EPA). Changes in EPA and BCAA contents after retort were determined by using LC-MS/MS. Nutrient values, osmolality, rheology and sensory acceptance of the processed fortified and control formulas were compared. After retort, the fortified formula had an increase in all types of BCAAs but 30% loss of EPA (p = 0.001). The fortified formula had slightly higher protein and fiber contents, along with increased osmolality. It had higher viscosity and shear stress, but similar IDDSI level at 0. Among flavors tested, the fortified formula with Japanese rice flavor received the highest satisfaction scores with over 80% sensory acceptance. In conclusion, retort sterilization preserved BCAAs of the functional drink, but the addition of 30% fish oil was required to compensate for the EPA loss. The sterilized fortified formula with Japanese rice flavor was sensory acceptable.

Investigating changes of proteome in the bovine milk serum after retort processing using proteomics techniques.

The objective of this study was to investigate the changes of the proteins in bovine milk serum after retort processing by label‐free quantification proteomics techniques. A total of 96 and 106 proteins were quantified in control group (CG) and retort group (RG), respectively. Hierarchical clustering analysis of the identified milk serum proteins showed a decrease in the abundance of most proteins, such as serum albumin, lactoperoxidase, lactotransferrin, and complement C3, and an increase in the abundance of other proteins such as κ‐casein, lipocalin 2, and Perilipin. Student's t‐test showed 21 proteins significantly differential abundance between CG and RG (p < .05), of which intensity‐based absolute quantification (iBAQ) of five proteins decreased and iBAQ of 16 proteins increased. Bioinformatics analysis demonstrated that retort processing increased the digestibility of proteins, but this improvement was offset by a decrease in the digestibility of proteins caused by protein modification. Our results provide insight into the proteome of retort sterilized milk for the first time. Given the extremely high security of retort sterilized milk, the proteome of bovine milk serum changes after retort sterilization exposed in this study will contribute to the formula design of retort sterilized milk products.

Thermodynamic interactions of micellar casein and oat β-glucan in a model food system

Oat β-glucan is a soluble dietary fiber and its consumption is associated with the reduction of coronary heart disease risk (21 CFR 101.81). Dairy and food formulations have been used to deliver β-glucan's health benefits to consumers, but the addition of β-glucan in dairy beverages can induce phase separation because of its thermodynamic incompatibility with micellar casein. Ten binary mixtures were developed with concentrations at 0.5–2% β-glucan and 0.75–6% casein to investigate the micellar casein–β-glucan interaction mechanism and evaluate the effect of biopolymer concentrations, thermal treatment, and ionic strength on these interactions. Pasteurization (73 °C/15 s) and retort sterilization (121 °C/5 min) were the two applied thermal treatments. Three dispersion media were used in the preparation of the binary mixtures: 5 mM potassium phosphate buffer, 171 mM NaCl in phosphate buffer, and milk permeate. Upon preparation, the samples were stored for 5 days at 4 °C and then centrifuged at 4000 rpm for 2 h. The phase diagrams showed that both thermal treatments increased the biopolymer compatibility and suspension stability. The thermally treated formulations exhibited smaller particle sizes, which explains the higher stability. Increasing ionic strength decreased the biopolymer compatibility and suspension stability and increased the particle sizes. Isothermal titration calorimetry (ITC) showed that the heat of binding was small indicating entropic biopolymer interactions. Confocal microscopy images illustrated the immiscibility of the two biopolymers showing the formation of two phases.

Quality characteristics of retort samgyetang marinated with different levels of soy sauce and processed at different F0 values.

The aim of this study was to develop retorted samgyetang marinated with different levels of soy sauce and processed at different F0 (thermal death time at 121°C) values. The tested marinade series comprised different percentages of soy sauce in water (0%, 25%, and 50% [w/w]) containing a fixed concentration of sodium tripolyphosphate (0.3% [w/w]). Following marination, samgyetang was prepared and subjected to retort processing, until an F0 value of either 8 or 29 was achieved. Meat quality analysis of the breast meat, sensory evaluation, and aroma analysis were performed as indicators of acceptability. The meat pH decreased as the soy sauce content increased, regardless of the F0 value. The shear force value significantly decreased as the concentration of soy sauce increased, but increased as the F0 value increased (p < 0.05). Lipid oxidation was not affected by marination, but increased significantly as the F0 value increased (p < 0.05). The proportion of polyunsaturated fatty acids decreased significantly (p < 0.05) as the F0 value increased. The total alkane content decreased as the F0 value increased (p < 0.05). Changes in the total volatile sulfur compound and 2-butyl-1-octanol content were affected by soy sauce marination. Marination using 25% soy sauce and retort sterilization, until an F0 value of either 8 or 29 was achieved, improved the acceptability of samgyetang. Therefore, marination using 25% soy sauce and retort sterilization until an F0 value of 8 is the process recommended for developing a soy sauce-flavored, retorted samgyetang product of acceptable quality.

Functionality of ultra-high barrier metal oxide-coated polymer films for in-package, thermally sterilized food products

Abstract Defects in metal oxide (MO)-coated polymer films increase their oxygen and water vapor transmission rates (OTRs, WVTRs), lowering the shelf-life of packaged food. In this study, we investigated the effects of thermal processing on six multilayered MO-coated films: MO-A (MO-coated PET(12 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (50 μm)), MO-B (SiOx-coated PET(12 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (60 μm)), MO-C (Overlayer/AlOx-organic-coated PET(13 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (50 μm)), MO-D (Overlayer/SiOx-coated PET(12 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (60 μm)), MO-E (AlOx-coated PET(12 μm)//AlOx-coated PET(12 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (70 μm)) and MO-F (AlOx-coated PET(12 μm)//AlOx-coated PET(12 μm)//AlOx-coated PET(12 μm)//Oriented-Nylon 6 (15 μm)//Cast-Polypropylene (70 μm)). Water filled film pouches were processed with a pilot-scale retort (30 and 40 min at 121 °C; F0 = 6–9 min) and microwave-assisted thermal sterilization unit (25-kW, single-mode, 915 MHz MATS system; F0 = 10.9 min). Subsequently, the pouches were emptied, filled with a color-changing oxygen sensor and stored at 23 ± 2 °C for 180-days. MO-F with three AlOx-coated PET layers, showed no oxygen permeation before and after retort and MATS processes. Compared to other films, MO-F exhibited low WVTRs after processing. Oxygen sensor in MO-F changed color at limited locations, indicating fewer defects. Confocal laser scanning microscope and scanning electron microscope images also showed less deterioration in MO-F. The dielectric loss factor (er) for MO-F was significantly less than other films (P

Development of a Method for Estimating the Time Point of Hair Contamination in Retort Pouch Foods

DNA from hair that has undergone retort pouch sterilization shows considerably more fragmentation. Assessing the extent of DNA fragmentation using a PCR assay could therefore be applied to infer the sterilization history of a contaminated food sample. Such assessments could make it possible to determine whether a food sample had been contaminated by hair during the production process. To determine the extent of retort pouch sterilization, primers specific for the detection of human DNA were designed to give an amplification product of approx 500 bp. Hair was subjected to retort sterilization as a model of contamination, and PCR was performed using the extracted DNA as a template and the primer set for determining retort pouch sterilization. The results showed that no DNA amplification occurred in retort pouch samples, whereas amplification was observed in samples that were unheated, heated in hot water, or heated in a microwave oven. The present method was thus able to specifically detect thermal decomposition of DNA from hair that had undergone retort sterilization, and will be useful for determining whether hair discovered in a retort pouch was responsible for contamination.

Estimation of Hardness of Cooked Rice during Retort Sterilization by Electric Impedance Measurement

Estimation of Hardness of Cooked Rice during Retort Sterilization by Electric Impedance Measurement

Modification of peanut protein isolate in glucose-containing solutions during simulated industrial thermal processes and gastric-duodenal sequential digestion

This research investigated the effects of commonly practiced thermal treatments (simulated pasteurization, retort sterilization and UHT sterilization) on peanut protein isolate (PPI)-glucose solution. Results showed that thermal treatment on PPI-glucose solution from mild to drastic conditions would lead to a more ordered and compact protein structure, greater extent of Maillard reaction, higher degree of graft, stronger in vitro antioxidant activities, but decrease in vitro digestion especially lower degree of hydrolysis in two-step enzymolysis by pepsin and then pancreatin. Compared with the unheated PPI-glucose solution, the Td values of ones autoclaved at 121 °C for 30 min and 45 min increased by 5% and 12%, and the ΔH of all the heated samples was lower than the unheated one. The present study indicated that retort sterilization or UHT sterilization treatment could be favourable in producing a beverage containing PPI and glucose with proper digestibility and post-digestion antioxidant activities.

Application of direct steam injection system to minimize browning of white radish (Raphanus sativus) broth during sterilization

Direct steam injection (DSI) was applied to minimize the quality changes of white radish (Raphanus sativus) broth during sterilization. This study compared the degree of browning of white radish broth from a retort sterilization system and a DSI system. The quality changes after thermal treatments, such as retorting and DSI, were evaluated by Lab color values, the browning index (BI) and sensory evaluation. As the volume of the retort pouch increased, the thermal processing time increased. Significant increases of a and b values, color difference and BI were observed. Unlike the retort sterilization, the DSI treatment showed no significant differences in color properties of the radish broth with a wide range of sterilization temperature. The highest sensory score among the DSI treated samples was observed at the lowest sterilization temperature (125°C). The results demonstrated that the DSI treatment showed a higher stability in the quality associated with the browning reaction, such as the color indices and BI because the DSI process rapidly increased the temperature of the radish broth by transferring the latent heat of steam to the fluid. Keywords: direct steam injection (DSI), retort, sterilization, quality, browning, white radish broth, sensory evaluation DOI: 10.25165/j.ijabe.20171006.3350 Citation: Ham T H, Yoon W B. Application of direct steam injection system to minimize browning of white radish (Raphanus sativus) broth during sterilization. Int J Agric & Biol Eng, 2017; 10(6): 210–220.

Ohmic heating: A promising technology to reduce furan formation in sterilized vegetable and vegetable/meat baby foods

Abstract Occurrence of furan, classified as carcinogen 2B by the International Agency for Research on Cancer, in heat-processed foods, especially sterilized baby foods, is of a health concern. On this account, innovative processing practices ensuring microbial safety, acceptable sensorial features, and, at the same time, minimizing furan formation have to be searched. In this study, the potential of ohmic heating to mitigate furan formation was demonstrated. Compared to conventional retort sterilization, significant mitigation (70–90%) of furan was achieved, assumingly due to reduced degradation of furan precursor under faster terms heating conditions. In purees containing meat, approx. two times less furan was formed, regardless of the processing technology. In addition to furan, also other headspace volatiles were measured and statistically evaluated. Compounds originated through fatty acids oxidation and Maillard reaction products were more abundant in conventionally sterilized samples compared to those treated by ohmic heating. Industrial relevance Ohmic heating is an emerging technology being employed in the field of food processing which applies a direct electric current to food products, providing rapid and uniform heating throughout the product. Shorter heating times used in ohmic heating, as compared to conventional retort sterilization, reduce potential losses of valuable nutrients and as well as reduce the formation of undesirable processing contaminants, in particular furan. The presented work examines furan concentrations across various stages of baby food production, in order to compare ohmic heating and retort sterilization processes. Volatile compound fingerprints for baby food purees processed via both sterilization methods, both prior and post sterilization were assessed. The results presented in this work are of high potential interest to the baby food industry to reduce both heat induced chemical changes and exposure of infants and babies to hazardous processing contaminants such as furan.

Composition and Variation of Macronutrients, Immune Proteins, and Human Milk Oligosaccharides in Human Milk From Nonprofit and Commercial Milk Banks

When human milk is unavailable, banked milk is recommended for feeding premature infants. Milk banks use processes to eliminate pathogens; however, variability among methods exists. Research aim: The aim of this study was to compare the macronutrient (protein, carbohydrate, fat, energy), immune-protective protein, and human milk oligosaccharide (HMO) content of human milk from three independent milk banks that use pasteurization (Holder vs. vat techniques) or retort sterilization. Randomly acquired human milk samples from three different milk banks ( n = 3 from each bank) were analyzed for macronutrient concentrations using a Fourier transform mid-infrared spectroscopy human milk analyzer. The concentrations of IgA, IgM, IgG, lactoferrin, lysozyme, α-lactalbumin, α antitrypsin, casein, and HMO were analyzed by mass spectrometry. The concentrations of protein and fat were significantly ( p < .05) less in the retort sterilized compared with the Holder and vat pasteurized samples, respectively. The concentrations of all immune-modulating proteins were significantly ( p < .05) less in the retort sterilized samples compared with vat and/or Holder pasteurized samples. The total HMO concentration and HMOs containing fucose, sialic acid, and nonfucosylated neutral sugars were significantly ( p < .05) less in retort sterilized compared with Holder pasteurized samples. Random milk samples that had undergone retort sterilization had significantly less immune-protective proteins and total and specific HMOs compared with samples that had undergone Holder and vat pasteurization. These data suggest that further analysis of the effect of retort sterilization on human milk components is needed prior to widespread adoption of this process.

Energy Efficiency Measures for Batch Retort Sterilization in the Food Processing Industry

Energy Efficiency Measures for Batch Retort Sterilization in the Food Processing Industry