Sterilization Temperature Research Articles

Optimisation of Not-from-Concentrate Goji Juice Processing Using Fuzzy Mathematics and Response Surface Methodology and Its Quality Assessment

Not-from-concentrate (NFC) juice effectively retains the original characteristics of the fruit. Despite the various health benefits of Goji berries, reports on the processing technology and quality changes of NFC goji juice are lacking. We optimised the processing technology of NFC goji juice. Employing fuzzy mathematics evaluation combined with response surface methodology based on single-factor experiments, the physicochemical, nutritional, and microbiological indicators of the juice were determined. Gas chromatography-ion mobility spectroscopy was used to analyse changes in volatile compounds before and after processing. The optimal processing parameters were: times for homogenisation, ultrasonication, and sterilisation of 2 min, 3 min, and 85 s, respectively, and sterilisation temperature of 102 °C. The resulting product had a sensory evaluation score of 85.5 and a rich, pleasant taste. The ratio of total soluble solids to titratable acidity and turbidity were 12.8 and 1420 NTU, respectively. Post-processing, the contents of β-carotene, polysaccharides, and betaine increased by 57.3%, 26.7%, and 31.5%, respectively. Microbiological indicators met Chinese national limits for food pollutants and microorganisms. The total relative content of volatile substances in NFC goji juice decreased by 19.86% after processing. This study provides a theoretical reference for the intensive processing and development of high-value goji berries.

Changes in whey protein produced by different sterilization processes and lactose content: Effects on glycosylation degree and whey protein structure

In this study, the interaction patterns between whey protein and lactose were investigated after different ratios of whey protein and lactose (1:2.5; 1:3.0; 1:3.5; 1:4.0; 1:4.5) were treated with two typical sterilization process parameters in powdered products (68 °C, 20 min; 72 °C, 15 min) and two typical sterilization process parameters in liquid products (121 °C, 10 min and 121 °C, 15 min). It was found that the degree of the Maillard reaction of whey protein-lactose solution increased with increasing lactose content, increasing sterilization temperature, or extending sterilization time, which was accompanied by changes in the protein structure of whey protein. In addition, glycosylation accelerates the decrease in free sulfhydryl content, decreasing surface hydrophobicity and decreasing fluorescence intensity. These findings highlight the advantages of designing protein-carbohydrate formulations with a high ratio of whey protein-lactose (1:2.5) to meet the requirements of the product standards for preterm/low-birth-weight infant formulas. When comparing only the sterilization processes of powder and liquid products, the pasteurization process of powder products significantly reduced the degree of the Maillard reaction caused by heat treatment and reduced protein denaturation.

Advantages of UHT in retaining coconut milk aroma and insights into thermal changes of aroma compounds

Coconut milk products are susceptible to bacterial damage, necessitating sterilization methods that often compromise nutrient and aroma integrity. This study investigates the effects of different thermal sterilisation methods on coconut milk aroma using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). We assessed the impact of pasteurisation (PAS, 70 °C, 25 min), high-temperature sterilisation (HTS, 121.1 °C, 15 min), and ultra-high temperature sterilisation (UHT, 130 °C, 5 s) through clustered heat maps and correlation analyses. Significant differences were observed (p < 0.05), with 37 and 52 substances detected by HS-GC-IMS and HS-SPME-GC-MS, respectively, identifying 12 key aroma compounds. UHT treatment primarily reduced 8 acids, maintaining a compositional structure and sensory profile similar to raw coconut milk. PAS and HTS treatments decreased the sensory intensity of overall coconut milk aroma, creamy, and floral notes, correlating with the presence of 2-heptanol, nonanal, 4-methylvaleric acid, and 2-tridecanone. These methods increased cooked notes, associated with 5-methyl-3-heptanone, 3-butyn-1-ol, hydroxyacetone, and acetoin. Rancidity was linked to acids such as isobutyric acid, isovaleric acid, and heptanoic acid, with high temperatures effectively reducing these compounds. Prolonged temperature changes in PAS and HTS accelerated lipid oxidative degradation and the Maillard reaction, involving free fatty acids in the formation of alcohols, aldehydes, esters, and lactones. These findings provide a theoretical basis for studying coconut milk flavour deterioration.

가열살균조건에 따른 양파 착즙액 첨가 한식간장의 저장 중 품질 특성 변화

The objective of this study was to integrate onion juice into traditional Korean soy sauce and to evaluate the sterilization conditions necessary for commercialization. As the sterilization temperature increased, pH decreased and titratable acidity increased. A reduction in °Brix was observed post-sterilization, from 37.37 °Brix in untreated soy sauce to 36.67-36.77 °Brix. In terms of chromaticity, the L value declined over the storage period while the a and b values increased. The quercetin component exhibited light sensitivity, with no significant difference observed in the sample on the 60th day. Neither Bacillus cereus nor Clostridium perfringens were detected, and the total bacterial count was comparable to that of commercially available soy sauce. This indicates that samples sterilized at 85°C for 30 minutes fall within a safe quality range. Sensory evaluation revealed that samples sterilized at 85°C for 30 minutes exhibited consistently high ratings.

가열살균조건에 따른 양파 착즙액 첨가 한식간장의 저장 중 품질 특성 변화

The objective of this study was to integrate onion juice into traditional Korean soy sauce and to evaluate the sterilization conditions necessary for commercialization. As the sterilization temperature increased, pH decreased and titratable acidity increased. A reduction in °Brix was observed post-sterilization, from 37.37 °Brix in untreated soy sauce to 36.67-36.77 °Brix. In terms of chromaticity, the L value declined over the storage period while the a and b values increased. The quercetin component exhibited light sensitivity, with no significant difference observed in the sample on the 60th day. Neither Bacillus cereus nor Clostridium perfringens were detected, and the total bacterial count was comparable to that of commercially available soy sauce. This indicates that samples sterilized at 85°C for 30 minutes fall within a safe quality range. Sensory evaluation revealed that samples sterilized at 85°C for 30 minutes exhibited consistently high ratings.

Characterization of Egg White Lysozyme from Local Duck Mojosari and Alabio

Lysozyme, a natural antibacterial, has potential use in several applications. Generally, it is obtained from chicken egg whites. However, the idea of using local duck eggs as a source of lysozyme is not wellknown. This study aimed to isolate and purify the egg white of Mojosari and Alabio ducks to characterize lysozyme. Additionally, the study analyzed the effect of temperature treatment on lysozyme enzymatic activity. Three different temperature treatments were used: Low Temperature Long Time (63 ℃, 30’), High Temperature Short Time (72 ℃, 15”), and sterilization (121 ℃, 15’). The Amberlite resin cation exchange chromatography method was successfully used to isolate and purify Mojosari and Alabio duck egg whites, achieving purity levels of 94.92-96.09%. The presence of lysozyme was confirmed by the existence of bands that were primarily composed of lysozyme. The results showed that each aspect of the characteristics of lysozyme and enzymatic activity were significantly affected (p&lt;0.05) by the type of egg white. Enzymatic activity indicated that Alabio duck lysozyme was thermosensitive and could only survive at LTLT temperature, while Mojosari duck lysozyme could survive at LTLT and HTST pasteurization temperatures. However, both lysozymes did not survive the sterilization temperature.

Effect and mechanisms of thermal sterilization methods on the in vitro phenolic bioaccessibility of rose tea with milk

Rose polyphenols, key functional components in roses, require adequate bioaccessibility for their health benefits, subject to influence by food components and processing. Investigating the impact of various thermal sterilization methods on the bioaccessibility of rose polyphenols in rose tea with milk and the underlying mechanisms, our findings indicated a significant increase in bioaccessibility following treatment at 85 °C/30 min. Conversely, 121 °C/15 min treatment decreased bioaccessibility. Examining the interaction between β-casein in milk and rose polyphenols under different sterilization conditions, SEM and particle size analysis revealed binding, with fluorescence spectroscopy indicating non-covalent bonds. Binding forces followed the order 121 °C > 85 °C > 25 °C. Notably, at 85 °C, non-covalent binding improved polyphenol bioaccessibility, while the intensified binding at 121 °C decreased it. SDS-PAGE and amino acid analysis confirmed no covalent bond. This study establishes a theoretical basis for selecting thermal sterilization temperatures for milk-flower combinations, considering polyphenol bioaccessibility.

Effects of steaming on physicochemical and emulsification properties of gum arabic

Gum arabic finds extensive application and typically undergoes sterilization prior to utilization in the food industry. This study explored the impact of steam sterilization temperature and duration on the physicochemical and emulsification characteristics of gum arabic, accompanied by proposed mechanisms elucidating observed effects. The results showed that when gum arabic was treated with high temperature sterilization (110 °C ∼ 140 °C), the emulsion prepared turned unstable. The interfacial tension decreased from 8.26 mN/m to 6.77 mN/m after sterilization, while the elastic modulus decreased from 23.65 mN/m to 16.16 mN/m. Moreover, the circular dichroic chromatographic results indicated that the arabinogalactan protein (AGP) structure of gum arabic was more relaxed after high temperature treatment with β-sheets content decreased from 36.2 % to 29.8 % and random coil content increased from 41.3 % to 51.8 %. Quartz crystal microbalance with dissipation (QCM-D) results demonstrated that emulsion surface film thickness and toughness decreased after sterilization treatment of gum arabic. The study indicates that high temperature sterilization may change protein structure in gum arabic and reduce the stability of prepared emulsions.

Modelling the Color and Microbial Properties of Canned Ngu by Response Surface Method

Background: Ngu is an African salad dressing used to improve the stability and shelf life of African salad. The aim of this study was to produce canned Ngu using three stabilizers at various concentrations, constant sterilization temperature, and varied sterilization times. Methods: Ngu (50 L) was prepared from potash using three stabilizers at various concentrations. A three-level factorial response surface design was applied to generate the experimental runs for the production of the canned Ngu. The Ngu emulsion was filled inside 250 ml bottle jars, sterilized at 121 oC at various times, and canned. The color of the canned Ngu was evaluated using the Comission Internationale de l'Eclairage color scale, and its microbiological attributes, Total Viable Count (TVC) and Total Fungal Count was determined with standard procedures. The effect of the stabilizers (Akparata, Ofo, and Carboxyl Methyl Cellulose), stabilizer concentration, and sterilization time on the color and microbial properties of the canned Ngu was assessed. The Statistical Software Design Expert version 8.0.7 was utilized for response surface analysis and derivation of model equation. Results: Increase in sterilization time increased the a* value and decreased the b* value of the canned Ngu. The quadratic effect of stabilizer, stabilizer concentration, and sterilization time indicated that the alteration of stabilizer from Carboxyl Methyl Cellulose to Akparata and then to Ofo increased the L* value, of the canned Ngu. An increase in the quadratic effect of stabilizer concentration increased the a* value but decreased the L* and b* values of the canned Ngu. However, the TVC and b* value of the canned Ngu reduced as the quadratic effects of the sterilization time increased. Conclusion: Total Fungal Count and TVC value of all the canned Ngu samples were within acceptable limits, ensuring the samples safe for human consumption.

Insight into the evolution of textural properties and juiciness of ready-to-eat chicken breasts upon different thermal sterilization: From the perspective of protein degradation.

Texture deterioration of meat products upon high-temperature sterilization is a pressing issue in the meat industry. This study evaluated the effect of different thermal sterilization temperatures on the textural and juiciness of ready-to-eat (RTE) chicken breast. In this study, by dynamically monitoring the texture and juiciness of chicken meat products during the process of thermal sterilization, it has been observed that excessively high sterilization temperatures (above 100°C) significantly diminish the shear force, springiness and water-holding capacity of the products. Furthermore, from the perspective of myofibrillar protein degradation, molecular mechanisms have been elucidated, unveiling that the thermal sterilization treatment at 121°C/10 min triggers the degradation of myosin heavy chains and F-actin, disrupting the lattice arrangement of myofilaments, compromising the integrity of sarcomeres, and resulting in an increase of approximately 40.66% in the myofibrillar fragmentation index, thus diminishing the quality characteristics of the products. This study unravels the underlying mechanisms governing the dynamic changes in quality of chicken meat products during the process of thermal sterilization, thereby providing theoretical guidance for the development of high-quality chicken products.

Bioactive Compounds and Nutrition of Thai Sauces in Retort Pouch and Physicochemical Properties Kinetics During Storage

The objectives of this study were to investigate the bioactive compounds, including carotenoids, flavonoids, total phenolics, antioxidant activity, and nutritional values of two ready-to-cook Thai sauces of stir-fry curry sauce (SCS) and spicy-sour sauce (SSS) in retort pouch and to investigate the kinetics of physicochemical properties, including lightness (L*), water activity, pH and total soluble solids, of the products during storage at 30°C and 55°C. The results showed that the temperature and time for sterilization of SCS (low acid foods) was 121°C for 43 minutes and SSS (acid foods) was 102°C for 31 minutes. The moisture content was between 57.9 and 63.2%. SCS had higher total fat, saturated fat, and calories because it contained soybean oil and chili paste, but SSS had higher sugar and sodium content than SCS. Trans fats and vitamin C were not detected in either product. SSS had a higher content of total phenols, carotenoids (especially capsanthin, zeaxanthin, and β-carotene) and antioxidants than SCS. The representation of the physicochemical properties of the products as a function of temperature and time resulted in a linear model (R2 = 0.7222 – 0.9772). L*, water activity, pH decreased, and TSS increased during the 90-day storage at both 30°C and 55°C. The change was more remarkable when stored at 55°C than 30°C.

Effects of different thermal sterilization conditions on the quality of ready-to-eat shrimp based on specific sterilization intensity

The effects of different thermal sterilization conditions on the quality and digestibility of ready-to-eat (RTE) shrimp were investigated. Compared with the high-temperature (121 °C) and short-time (6 min and 8 min) sterilization, the low-temperature (110 and 115 °C) and long-time (>20 min) sterilization significantly promoted the Maillard and browning reactions and changed the color of the RTE-shrimp. The high sterilization temperature promoted shrimp protein oxidation, resulting in increased carbonyl group, disulfide bond, and free radical content, while the free sulfhydryl group content decreased. This oxidation and tissue destruction at high temperature led to reduced texture properties and altered water distribution within the shrimp's muscles. However, sterilized shrimp exhibited superior digestive properties in an in vitro simulated digestion experiment. High-temperature and short-time sterilization is more effective in mitigating the quality deterioration of RTE-shrimp compared to low-temperature and long-time sterilization.

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.

The Design and Process Parameters for the Optimization of an Ultrasonic—Thermal Co-Sterilization System for Liquid Eggs

The sterilization of liquid eggs plays a crucial role in the production of liquid egg products. Traditional pasteurization techniques can easily cause protein denaturation, while non-thermal sterilization techniques are often constrained by processing intensity and time. Improving the effectiveness of liquid egg sterilization while preserving the stability of its functional attributes poses a significant challenge. In response to this issue, a synergistic ultrasonic mild thermal sterilization system for liquid eggs is proposed, accompanied by the optimization of its process parameters. COMSOL is employed to simulate the acoustic field distribution of the ultrasonic–thermal system in the liquid egg medium. Verification is conducted through acoustic intensity measurements, and analysis is performed to obtain the optimal arrangement of ultrasonic transducers. Based on Modbus communication, an ultrasonic–thermal synergistic sterilization system is designed. Sterilization experiments are conducted with both 20 kHz + 28 kHz and 20 kHz + 40 kHz multifrequency ultrasound, compared with traditional 20 kHz single-frequency ultrasound. The results indicate that multifrequency ultrasound improves sterilization efficiency by approximately 15% compared to traditional single-source ultrasound. Utilizing multifrequency ultrasonic–thermal synergistic sterilization experiments, a three-factor, three-level response surface test is conducted with sterilization rate and foaming properties as evaluation criteria. The results indicate a strong correlation between ultrasonic frequency, processing time, heating temperature, and sterilization performance, with the impact magnitude being sterilization temperature &gt; processing time &gt; ultrasound frequency. Parameter optimization analysis is performed using a genetic algorithm, yielding sterilization conditions of 55 °C, 11 min and 30 s processing time, and 20 + 40 kHz ultrasonic frequency. The liquid egg sterilization rate is 99.32%, an average decimal reduction of 3.17 log values, and foaming properties are 42.79%.Through comparative analysis, it is determined that the sterilization rate of the ultrasonic–thermal synergistic sterilization system meets national standards, and functional properties such as foaming are superior to traditional pasteurization. This validates the proposed ultrasonic–thermal synergistic liquid egg sterilization control system as effective and feasible.

An NIR-II-enhanced nanozyme to promote wound healing in methicillin-resistant Staphylococcus aureus infections

Deep tissue bacterial infections, especially methicillin-resistant Staphylococcus aureus (MRSA) infections, pose challenges to clinical therapy due to their low debridement efficiency and relapsing. Molybdenum disulfide (MoS2) is used in the antibacterial field as a classic photothermal agent (NIR-I) with good biocompatibility. However, due to its limited NIR-I tissue penetration ability and single treatment mode, MoS2 has poor therapeutic effects on deep tissue infection. Herein, we prepared a defect-type hybrid 2H-MoS2 nanozyme (MoWS2) using hydrothermal method fabricate the MoWS2 composite, which is a new antibacterial strategy involving photothermal and enzyme catalysis, and further enhances the activity of the nanozyme through overheating. The regulation of 2H-MoS2 defects through tungsten ion doping endows MoWS2 with better near-infrared two-region absorption (NIR-II) and enzyme catalytic performance. Antibacterial activity experiments in vitro have shown that MoWS2 can achieve efficient bactericidal activity and biofilm clearance through hyperthermia and reactive oxygen species (ROS). Deep MRSA infection experiments have shown that MoWS2 rapidly removes bacteria from subcutaneous infected tissues through photothermal therapy (PTT) and chemodynamic therapy (CDT), accelerates the dissipation of abscesses, and promotes the healing of infected wounds. Additionally, the versatile treatment mode of MoWS2 was further confirmed through tissue sectioning and immunofluorescence staining analysis. Overall, these results provide a feasible approach for achieving efficient treatment of deep tissue infections through tungsten ion doping to regulate defective 2H-MoS2. Statement of significanceThe photothermal effect of MoS2 nanosheets in the NIR-I (650-900 nm) window in anti-MRSA therapy is considered to be highly reliable and efficient in PTA. However, most of the developed PPT therapies or antimicrobial systems based on PTT therapies developed with 1T-MoS2 have in vivo sterilization temperatures of more than 55°C, which have the risk of damaging the normal tissues of the skin. In this study, we prepared W@MoS2 with a good photothermal effect (36.9%) in the NIR-II window and good peroxidase-like activity. The combined effect of PTT and CDT has a stronger bactericidal effect while avoiding high-temperature damage, which makes the W@MoS2 material more advantageous in terms of antimicrobial effect.

3D printer-driven design of a non-assembly titanium surgical instrument using compliant lattice flexures

Metal additive manufacturing is a promising technology for the production of functional medical products, due to its high shape complexity and resolution, and ability to withstand sterilization temperatures. This study explores the possibility of designing a completely non-assembly steerable surgical instrument using Selective Laser Melting. Despite its advantages for medical devices, the rough surface quality of unfinished parts can be problematic for non-assembly designs, leading to increased friction and wear in rigid body mechanisms and tendon-actuated mechanisms. We investigated printing of rolling contact joints with crossed flexures as low-friction joints, adjusted for printing in titanium for the design of the instrument. Grid-based lattice structures were incorporated as miniature flexures, and we explored the influence of various grid sizes on the flexibility and bending stiffness of the lattices. Based on this exploration, we altered the rolling joint configuration from two crossed flexures to a single straight flexure for our design. The resulting steerable surgical instrument design is completely non-assembly, including its actuation, facilitates easy removal of support structures, and requires no surface finishing steps. It has a diameter of less than 20 mm, facilitates opening and closing of a grasper, and steering of the grasper by 20 degrees.

Dextran sulfate acting as a chaperone-like component on inhibition of amorphous aggregation and enhancing thermal stability of ovotransferrin

The tendency of ovotransferrin (OVT) to unfold and aggregate under 60 °C severely restricted sterilization temperature during egg processing. Searching for efficient strategies to improve OVT thermal stability is essential for improving egg product quality and processing suitability. Here, we investigated the effect of sulfate polysaccharide (dextran sulfate, DS) on heat-induced aggregation of OVT. We found that DS can effectively suppress amorphous aggregation of OVT at pH 7.0 after heating. Strikingly, the addition of 5 µM DS fully suppressed insoluble aggregates formation of 0.5 mg/mL OVT. Structure analysis confirmed that DS preserves nearly the entire secondary and tertiary structure of OVT during heating. The steric hindrance effect arising from strong electrostatic interactions between OVT and DS, coupled with reduced OVT hydrophobicity, is the underlying mechanism in suppressing protein–protein interactions, thus enhancing thermal stability. These findings suggest DS could act as protein stabilizers and chaperones, enhancing the thermostability of heat-sensitive proteins.

Effects of heat sterilization on protein physicochemical properties and release of metabolites of braised chicken after in vitro digestion

Heat sterilization enhances the safety and shelf-life of braised chicken, but its impact on protein digestibility and the release of metabolites remains unclear. Here, braised chicken was sterilized at 80 °C (LS), 100 °C (MS), and 121 °C (HS) for 30 min. Protein digestibility was assessed by in vitro digestion, whereas the release of metabolites was analysed by UPLC-QTOF-MS spectroscopy. Results revealed that LS had higher gastrointestinal digestibility (88.86 %) than MS (81.79 %) and HS (78.13 %). Increased carbonyl content, turbidity, particle size, and hydrophobicity, along with decreased sulfhydryl content and solubility, indicated rising protein oxidation aggregation with higher sterilization temperatures, explaining reduced digestibility. 96 metabolites were identified. Compared to the control group, LS exhibited a statistically significant variation in the biosynthesis of unsaturated fatty acids, MS displayed a significant difference in purine metabolism, and HS showed a significant difference in primary bile acid biosynthesis. Thus, LS is a promising sterilization method.

Application of a temperature and pressure detector to the preventive maintenance of hospital autoclaves

Pressure steam sterilization is the preferred sterilization method for damp-heat resistant medical devices. This study aims to reveal the risk of sterilization failure by using temperature and pressure detectors to detect changes in the performance of the sterilizer. Six autoclaves in a general hospital were selected as the research objects, and the key sterilization parameters such as sterilization temperature, sterilization time, sterilization pressure, and equilibration time were verified, and the performance of the sterilizer was evaluated. This paper provides a new way to monitor the sterilization process and to detect hidden dangers.

A new strategy for maintaining the thermal stability of phycocyanin under acidic conditions: pH-induced whey protein isolate-phycocyanin coprecipitation forms composite with chitosan

Phycocyanin is prone to degradation under acidic conditions and unstable at high temperatures, which is a key scientific issue limiting its application in food. Many methods have been used to maintain the stability of phycocyanin, but no excellent method has emerged. In order to achieve the application of phycocyanin in food (especially in beverages), this study innovatively utilized an effective method to combine phycocyanin with whey protein isolate by protein coprecipitation, and then coat it with chitosan to form composite particles. The composite particles not only maintained the blue color of phycocyanin, but also had colloidal stability. By simulating the conditions of pasteurization, high temperature short-term sterilization (HTST) and ultrahigh temperature transient sterilization (UHT), the color of the whey protein isolate (WPI) - phycocyanin (PC) - chitosan (CS) composite solutions (pH = 3) changed slightly before and after heating, without significant apparent differences. The UV–vis spectra showed that the highest and lowest pigment retention rates of WPI-PC-CS composite can reach 96.41% and 81.63%, respectively. The results of particle size, ζ-potential, SDS-PAGE, intrinsic fluorescence and FTIR analysis showed that phycocyanin was encapsulated in the helical structure of whey protein isolate, and chitosan was effectively attached to the surface of coprecipitated particles. Meanwhile, WPI-PC-CS composite also had excellent antioxidant capacity after heating. WPI-PC-CS composite had broken through the limitations of other materials in food applications and expanded the application of phycocyanin in acidic beverages and other food forms.