A Comprehensive Review on the Recent Technological Advancements in the Processing, Safety, and Quality Control of Ready-to-Eat Meals

Abstract

Ready-to-eat meals (RTEMs) are increasingly popular due to their convenience, but ensuring their safety and quality presents significant challenges. This comprehensive review analyzes recent technological advancements in RTEM safety control throughout the entire supply chain, from raw material sourcing to consumer consumption. We examine cutting-edge detection methods, including chromatography–mass spectrometry, real-time PCR, and CRISPR-based techniques for contaminants such as pesticide residues, veterinary drugs, heavy metals, and microorganisms. The review also explores innovative sterilization processes, such as irradiation, microwave, and radio frequency technologies, emphasizing their impact on microbial safety and product quality. Furthermore, we discuss the crucial role of packaging innovations, including modified atmosphere packaging, functional antimicrobial materials, and intelligent packaging systems, in preserving RTEM freshness and extending shelf life. This review provides valuable insights into current trends and future directions in RTEM safety and quality control, aiming to contribute to sustainable growth and consumer confidence in this rapidly expanding industry.

1. Introduction

With global economic development and accelerating life pace, ready-to-eat (RTE) foods, as significant products of the modern food industry, are experiencing rapid growth. The RTEM industry originated in the United States during the 1980s, triggered by a “food revolution” due to the rapidly growing consumer demand for convenient foods (Figure 1) [1]. Subsequently, the industry developed swiftly in developed countries such as Japan, establishing complete industrial chains and standardized systems. According to global market research data, the RTEM market is projected to exceed USD 7.3 trillion by 2025, maintaining a compound annual growth rate above 8.5% (https://www.futuremarketinsights.com/reports/ready-to-eat-food-market (accessed on 10 December 2024)). In addition, the prefabricated vegetable markets show different characteristics in the global scope (https://www.sphericalinsights.com/reports/ready-to-eat-food-market (accessed on 3 March 2025)). For example, in North America and Europe, prefabricated markets are mature, and consumer demand for healthy and convenience foods is growing. In the Asian Pacific region, the market is growing rapidly, especially in countries such as China and India, where the demand for prepared vegetables is increasing due to the faster pace of life and changing consumer habits. These data and analyses provide important perspectives for understanding the dynamics and potential of prefabricated vegetable markets worldwide.

RTEMs refer to food products that undergo processing steps, including washing, cutting, and pre-cooking, and are stored and distributed under frozen, refrigerated, or ambient conditions with appropriate packaging. These products primarily utilize raw materials from agricultural products, poultry, livestock, and aquatic products and can be consumed directly or after minimal heating [2]. Based on the different product forms, RTE meals (RTEMs) can be categorized into four types: ready-to-heat, ready-to-eat, ready-to-cook, and ready-to-assemble (Figure 2). Most of the frozen RTEMs need to be processed after heating and thawing. According to the main ingredients used, RTEMs can be further classified into pre-processed vegetable products, pre-processed seafood products, pre-processed poultry and livestock products, etc. Based on the temperature required during distribution, they can be divided into three categories: ambient temperature distribution RTEMs, refrigerated distribution ready-to-eat meals, and frozen distribution RTEMs [3,4].

While these products offer significant advantages in convenience and operational cost reduction for food service businesses, they face safety challenges due to potential microbial contamination during production, storage, and transportation, as well as quality issues such as nutritional loss [5,6].

World Health Organization assessment indicates that contaminated food can cause or transmit over 200 different types of diseases, posing particular threats to vulnerable populations such as the elderly, pregnant women, and infants [7]. Therefore, ensuring food safety throughout the RTEM supply chain, from production and processing to transportation and storage, is crucial (Figure 3). Recent years have witnessed substantial improvements in RTEM safety control through innovations in detection methods, sterilization processes, and packaging technologies, particularly in raw material quality control, processing safety management, and packaging innovations [8]. Despite the continuous expansion of the RTEM market, food safety remains a key factor limiting the industry’s development. Studies have shown that cross-contamination is common during the production process of RTEMs, improper temperature control during storage and transportation can lead to microbial contamination, and some regions lack unified quality standards and regulatory systems [9]. This issue is particularly prominent in the rapidly developing Asia–Pacific market, where problems such as inadequate cold chain logistics and low standardization of production processes are especially challenging. Furthermore, the technical issues related to nutrient loss and deterioration in taste still need to be addressed, as solving these problems will directly impact the sustainable development of the industry [10].

This review systematically examines recent technological advances in RTEM safety control, focusing on innovations in key areas such as detection methods, sterilization processes, and packaging technologies while also providing insights into future development trends, aiming to contribute to the healthy and sustainable development of the RTEM industry.

The literature search was conducted using prominent databases such as Web of Science, Science Direct, and Scopus. The search string employed a combination of keywords, including ready-to-eat food, prepared meals, safety, quality, and contamination. The time frame for the literature search spanned from the years 2000 to 2024. The inclusion criteria for the selection of literature were stringent, limited to English-language peer-reviewed articles, highly cited papers, and authoritative reviews. A flowchart depicting the literature screening process is appended for clarity (Figure 4).

2. Quality and Safety Control of Raw Materials

Quality control of raw materials is crucial for ensuring the safety of RTEM foods. Due to their diverse sources of raw materials and complex processing technologies, RTEMs face multiple safety risks throughout the farm-to-table chain. Studies have shown that raw materials may be contaminated by pesticide residues, veterinary drug residues, heavy metals, microorganisms, and mycotoxins during cultivation, breeding, storage, and transportation [11].

These contaminants not only endanger consumer health but may also generate secondary hazards during subsequent processing. For example, in a study, the microbial content of the samples exceeding 10⁵ CFU/g was detected by testing the total number of colonies, indicating a serious problem in microbial contamination of ready-to-eat meat products [12]. Studies have shown that in the production process of ready-to-eat salad, E. coli, Salmonella, Staphylococcus aureus, and other microorganisms will cause its corruption [13]. At the same time, study analysis found that under different production conditions, there are differences in microbial contamination of street- and market-vended ready-to-eat grasshopper. These cases suggest that ready-to-eat foods face challenges with multiple microbial contamination during production and distribution. Therefore, establishing a systematic raw material quality and safety control system is vital for the sustainable development of the RTEM industry.

2.1. Contamination Detection in RTEMs

Recent innovative developments in raw material safety detection technologies have provided technical support for source safety control of RTEMs (Figure 5).

Table 1. Application of different detection techniques in RTEM.

Food Name	Detection Index	Detection Method	Refs
Meat	Pesticide residue	LC-MS/MS	[14]
Chicken	Veterinary drug residue	GC-MS/MS	[15]
Seafood	Salmonella	Real-time PCR	[16]
Vegetables	Escherichia coli O157:H7	ELISA	[17]
Fruit	Heavy metal	Inductively coupled plasma mass spectrometry (ICP-MS)	[18]
Wheat grains	T-2 mycotoxins	Surface-enhanced Raman spectroscopy (SERS)	[19]

shows the application of different detection techniques in RTEM.

In the field of pesticide and veterinary drug residue detection, chromatography–mass spectrometry coupling technology has achieved significant breakthroughs. High-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) has become the gold standard for residue detection due to its ultra-high sensitivity and selectivity [14,15,20]. This technology can simultaneously detect and quantify hundreds of agricultural and veterinary drug residues with detection limits reaching ng/kg levels. The application of ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS/MS) has further improved detection throughput and enables structural identification of unknown compounds [21]. Recent research shows that non-targeted screening strategies combined with artificial intelligence algorithms can identify novel contaminants that are difficult to detect using traditional methods [22].

Microbial contamination, as one of the main threats to RTEM raw material safety, has undergone significant evolution in detection technology from traditional cultivation methods to molecular biological approaches. Real-time fluorescent quantitative PCR technology has significantly shortened detection time while providing more accurate quantification results [16,23]. The ELISA technology has been reported to detect the amount of E. coli in fresh vegetables [17]. Novel detection methods, such as the combination of immunomagnetic separation (IMS) with PCR, enable enrichment and rapid detection of pathogens in complex matrices [24]. CRISPR-based nucleic acid detection technology demonstrates extremely high specificity and sensitivity, showing broad application prospects in the rapid screening of foodborne pathogens [25]. Additionally, the development of microfluidic chip technology has made portable on-site detection possible, particularly suitable for rapid screening at production sites [26]. Despite progress, challenges remain, such as the complexity of food matrices, the need for sophisticated laboratory equipment, and the cost of efficient testing methods [27]. These factors pose challenges for food producers and testing agencies.

Progress in heavy metal contamination detection technology is primarily reflected in the optimization of instrumental analysis methods and innovation in sample pretreatment techniques. Inductively coupled plasma mass spectrometry (ICP-MS) combined with ion chromatography systems can not only measure total heavy metal content but also analyze their valence state distribution, providing more comprehensive data support for contamination risk assessment [18]. Novel nanomaterials show unique advantages in sample pretreatment, such as magnetic nanomaterials efficiently enriching trace heavy metals, significantly improving detection sensitivity [28].

The prevention and control of mycotoxin contamination has shifted from single detection to comprehensive management. The development of multi-component simultaneous detection technology has made it possible to screen multiple mycotoxins in a single analysis. Aptamer sensors based on surface-enhanced Raman spectroscopy (SERS) achieve rapid and sensitive detection while maintaining excellent specificity [19]. Furthermore, the establishment of predictive models helps evaluate mycotoxin production risks under different environmental conditions, providing a basis for preventive control [29].

2.2. Adulteration in RTEMs

Adulteration in RTEM products involves deliberate food manipulation through the introduction, blending, or substitution of substandard or dangerous substances. Consuming adulterated foods can trigger allergic reactions, foodborne illnesses, or chronic health issues from toxic contaminants. Common RTEM adulteration includes raw material substitution, unauthorized additive use, and misleading labeling.

Raw material substitution occurs when cheaper meat or seafood varieties replace advertised products or authentic cheese is substituted with inferior alternatives. For example, misrepresenting freeze–thaw smoked salmon as fresh reduces quality and deceives consumers. Pezzolato et al. demonstrated histology’s effectiveness in detecting such fraud in premium products like smoked salmon [30]. Proteomics widely identifies protein substitution in meat products with a 1% detection threshold, confirming product authenticity [31]. Real-time PCR verifies DNA in aquatic products, detecting adulteration at 0.1% levels essential for confirming seafood species and origin [32].

Illegal additives involve prohibited chemicals or excessive amounts of permitted additives like colorants, preservatives, or flavor enhancers. Inductively coupled plasma mass spectrometry (ICP-MS) is preferred for elemental analysis in nutrient-fortified foods, with detection limits as low as 0.01 mg/kg, ensuring accurate nutrient addition and absence of harmful elements [33].

In summary, the safety and quality of ready-to-eat meal (RTEM) products depend on strict control measures throughout the production chain. Raw materials face numerous contaminants, including pesticide and veterinary drug residues, heavy metals, microbial pathogens, mycotoxins, and adulterants, which present health risks and may cause product deterioration. Modern detection methods such as HPLC-MS/MS for residue analysis, real-time PCR and CRISPR-based techniques for pathogen identification, and ICP-MS for heavy metal detection provide effective tools for monitoring these hazards. Nevertheless, limitations remain regarding costs, complex food matrices, and equipment requirements. Additionally, economically motivated adulteration highlights the need for vigilance and effective regulations. A comprehensive approach combining advanced detection technologies, preventative strategies, and consumer awareness is necessary to reduce risks and maintain RTEM product safety. Ongoing innovation and cooperation between the food industry, regulatory authorities, and research institutions are essential to address emerging challenges in RTEM food safety.

3. Quality and Safety Control in the Production and Processing Stages

Microbial contamination is the main safety risk during the processing of RTEMs. Feglo et al. identified a variety of microorganisms present in RTEMs, including Staphylococcus aureus, Bacillus species, Klebsiella pneumoniae, and Escherichia coli (E. coli) [34]. Additionally, Gizaw et al. also identified various bacterial species responsible for food poisoning and foodborne diseases, such as Salmonella, Shigella, and E. coli [3]. Research by Mengistu et al. [2] showed that bacteria in RTEMs, such as Enterobacter species (11.3%), Klebsiella species (9.1%), Bacillus cereus (26.8%), and Pseudomonas species (6.1%), exceeded the hygienic standard limits and could pose potential health risks. Furthermore, Listeria monocytogenes, a pathogen capable of growing in low-temperature environments and resistant to salt and nitrites, is commonly detected in RTE meat products [4]. Therefore, one of the significant challenges faced by the RTEM processing industry is how to improve the microbiological safety of their products while preserving the nutritional value and flavor of the meals.

3.1. Control of Microorganisms in RTEMs Through Sterilization Technologies

Sterilization technologies play a crucial role in the production of RTEMs, as they can effectively control the microbial load, ensure food safety, and extend the shelf life of the products.

Table 2. Application of different sterilization techniques in the processing of RTEMs and their effect on products.

Product	Sterilization Technology	Factor	Effect	Refs
Pre-made stir-fried chicken with chili peppers	γ-ray	10/20 kGy	Ensure shelf stability, microbiological safety, organoleptic quality, and nutritional value of pre-made dishes	[35]
Pre-made mixed vegetables	γ-ray	1 kGy	Reduced microbial contamination levels in pre-made mixed vegetables	[36]
Pre-made chicken breasts	γ-ray combined refrigerated and vacuum-packed processing	25 kGy	Extend shelf life to 60 days	[37]
Pre-made chicken breasts	γ-ray	40/5 kGy	After 10 days of irradiation treatment, the 40 kGy irradiated samples showed a more significant improvement in microbiological quality than the 5 kGy but were also accompanied by off-flavors that could affect sensory properties	[38]
Pre-made smoked osprey	X-ray	2.0 kGy	Highly effective in killing bacteria without altering their flavor	[39]
Pre-made shrimp	X-ray	0.75 kGy	Significantly reduced the initial flora on the surface of prepared shrimps below the detectable limit	[40]
Simulated pre-made carrots	Microwave/hot water		Retained the color of carrots better treated by microwave	[41]
Pre-made carrots	Nano-zinc oxide composite radio frequency heating	6 kW, 27 MHz, 20 min	Significantly reduced colony counts during storage and extended shelf life up to 60 days compared to carrots treated only with radio frequency heating	[42]
Pre-made broccoli	γ-ray with active coating	0.4 kGy	Active coating and irradiation treatment had a synergistic sterilizing effect on prepared broccoli, extending shelf life	[43]
Raw tuna fillets	X-ray	0.6 kGy	Significant (p < 0.05) decrease in Salmonella enterica counts	[40]
Pre-cooked ham	Thermal sterilization	90.6–96.1 °C for 2 min	Reduced mixture of four Listeria monocytogenes strains significantly	[44]
Pre-made low-fat turkey jumbo salami	Thermal sterilization	85 °C water bath heating for 10 s	Inactivated all Listeria monocytogenes on the surface	[45]
Pre-made poultry	Microwave	900 W for 90 s	Effective removal targets bacteria	[46]
Pre-made spinach	Electron beam	Aerosol packaging (100% O2 and N2:O2 [2:1]), low dose (less than 1 kGy)	Reduced Salmonella spp. and Listeria spp.	[47]
Pre-made beef jerky	Electron beam	10 kGy	Significantly reduced the total number of aerobic bacteria, increasing microbiological safety without altering the jerky quality	[48]
Pre-made Iberian dry-cured ham, dried beef, and smoked tuna	Electron beam	1.5 kGy	Increased the shelf life of the product	[49]

summarizes the application of various sterilization techniques in RTEM processing and their potential impacts on the products. Different sterilization techniques offer distinct advantages and limitations, as summarized in

Table 3. Comparison of advantages and disadvantages of different sterilization technologies.

Sterilization Technology	Advantages	Disadvantages
Thermal sterilization	Reducing/eliminating pathogens that cause foodborne illness; extend shelf life	Impact on food sensory and quality; long processing time
Irradiation	Reducing/eliminating pathogens that cause foodborne illness; extending shelf life; no residual hazardous substances or additional nutritional changes; high sanitation and permeability; package products; no heat or wastewater generation	Require equipment to prevent radiation leakage; produce off-flavors after irradiation; exist concerns about irradiation technology
Microwave	Shorten heat treatment time; reduce the impact of heat treatment on food quality; sterilization	Uneven heating
Radiofrequency	Rapid heating; sterilization; stronger penetration ability	Uneven heating

.

3.1.1. Conventional Thermal Sterilization

Thermal sterilization, a widely employed method for microbial inactivation in the food industry [9], plays a crucial role in maintaining food freshness and safety. High-temperature treatments effectively eliminate microorganisms, thereby extending shelf life. For instance, heating Listeria monocytogenes inoculated onto the surface of pre-cooked ham packaging at 90.6–96.1 °C for 2 min significantly reduced bacterial counts [44]. Similarly, a 10 s exposure to an 85 °C water bath effectively eliminated L. monocytogenes inoculated onto low-fat turkey frankfurters [45]. Studies have shown that conventional heat sterilization can cause the inactivation of microorganisms, including mesophilics and thermophiles, to ensure the eradication of spoilage and food poisoning [50]. However, while thermal sterilization prolongs shelf life, it often compromises sensory attributes (e.g., color and flavor), rheological properties, and nutritional value. Studies have demonstrated the detrimental effects of thermal processing on various food products. For example, changes in texture have been observed in canned sardines and Indian mackerels, along with alterations in color, shear force, cooking loss, and elasticity in salmon muscle [51]. Mud cans are canned products made by crushing the food, stirring up the resulting meat, and then going through a certain heat sterilization procedure. However, after the chestnut mud is made into cans for disinfection, the chestnut mud near the edge of the can wall will browbrown, causing a waste of food [52]. Furthermore, conventional high-temperature sterilization processes can be constrained by packaging limitations and pose a risk of product recontamination. Therefore, despite its efficacy in microbial control, thermal sterilization requires careful consideration of the balance between microbial safety and product quality. Traditional high-temperature sterilization may not be suitable for certain ready-to-eat (RTE) meals due to potential adverse effects on sensory characteristics, potentially leading to consumer rejection [53]. Consequently, milder processing methods are needed to preserve both quality and microbial safety in RTE products.

Recent research on food processing technologies has demonstrated the considerable potential of autoclave heat sterilization (HPTS) and related methods. One study thoroughly examined HPTS advantages compared to conventional heat treatment in reducing processing contaminants while preserving food quality attributes [54]. The findings confirmed that HPTS effectively minimized processing contaminants while maintaining high food quality. Additionally, significant advancements have been made in high hydrostatic pressure (HHP) treatment applications for food preservation [55]. This technology effectively inactivates microorganisms and enzymes, resulting in higher-quality foods with extended shelf life and enhanced safety.

Additional research has evaluated how various sterilization techniques affect food quality. For instance, one study comparing the effects of HV, thermal pasteurization, and heat sterilization on pickle juice color and nutrient content provided valuable data for food processing applications [56]. Another investigation revealed synergistic bactericidal effects of combined high-pressure and -temperature treatments on fruits and vegetables, offering important insights into high-pressure applications for food preservation [57].

Furthermore, high-pressure processing at room temperature (HPP) for pasteurizing foods and beverages has gained attention. Research indicates that HPP effectively inactivates key microbial pathogens, including Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, and Salmonella, thereby ensuring food and beverage safety [58]. Collectively, these studies highlight the significant value of autoclaves and other high-pressure techniques in food processing applications.

3.1.2. Irradiation Sterilization

Irradiation sterilization, a non-thermal process, inactivates microorganisms by exposing food to a controlled dose of ionizing radiation, typically gamma rays, X-rays, or electron beams [51]. This technology, already widely used in agriculture and food processing, holds considerable promise for broader applications within the food industry. Its advantages over conventional sterilization methods include high efficiency, comprehensiveness, versatility, and energy conservation [59].

Gamma Irradiation

Irradiation achieves sterilization by transferring energy from ionizing radiation to the food product. Gamma rays, a highly penetrating form of ionizing radiation typically generated by radioactive isotopes (commonly cobalt-60), can penetrate both the surface and interior of food, effectively eliminating microorganisms [60]. One study investigated the effects of varying gamma irradiation doses on the microbial safety, sensory quality, and protein content of pre-cooked diced chicken with chili peppers. Results indicated no significant impact on product quality at doses of 10 kGy and 20 kGy [35]. Another study demonstrated that a 1 kGy gamma irradiation dose significantly reduced microbial contamination and extended the shelf life of pre-cut fresh fruits and mixed vegetables [36]. A high dose of gamma irradiation (25 kGy), combined with refrigeration and vacuum packaging, effectively preserved the nutritional content of pre-cooked chicken breast, achieving sterility and extending shelf life [37]. Research has also shown that a 40 kGy gamma irradiation dose provided superior microbial control compared to a 5 kGy dose in pre-cooked chicken breast but potentially impacted sensory characteristics (e.g., off-odor) [38]. Furthermore, the combination of active coating and gamma irradiation exhibited a synergistic effect on the sterilization of pre-cooked broccoli, further extending its shelf life [43]. Smita et al. analyzed the physicochemical properties of the four colored rice noodles and found that the viscosity of the colored rice noodles decreased after γ-ray irradiation [61]. These findings suggest the potential of gamma irradiation for sterilization and shelf-life extension in various RTEMs. However, careful dose selection is crucial to balance sterilization efficacy with product quality.

X-Ray Irradiation

X-rays, generated by high-energy electron streams produced when fast-moving electrons strike a metal target, possess high penetration capabilities. It is able to destroy the biofilms of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes to achieve the sterilization effect [62]. One study evaluated the sterilization efficacy of X-ray irradiation on pre-cooked, vacuum-packed smoked mullet. Samples irradiated at different doses (0 kGy, 0.5 kGy, 1.0 kGy, 1.5 kGy, and 2.0 kGy) were analyzed for microbial populations and sensory quality during storage. Results indicated effective sterilization without compromising flavor [39]. Another study inoculated shrimp samples with pathogenic bacteria and treated them with varying X-ray irradiation doses (0.1 kGy to 4.0 kGy). Doses of 2.0 kGy, 3.0 kGy, and 4.0 kGy reduced microbial counts to below the detection limit. Moreover, X-ray treatment improved the quality of raw tuna fillets inoculated with Salmonella enterica [63]. Similarly, X-ray irradiation of S. enterica at increasing doses resulted in significant reductions in bacterial counts [40]. These studies suggest that X-ray irradiation can effectively sterilize and enhance the microbial safety of various RTEMs while preserving flavor and quality.

Electron Beam

Electron beam (e-beam) irradiation, a cost-effective, environmentally friendly, and time-efficient alternative to conventional thermal decontamination [64], offers advantages in terms of cost, environmental impact, and processing time. However, its effectiveness depends on factors such as irradiation dose, food composition, and microbial species. One study investigating e-beam irradiation of three vacuum-packed RTE products (Iberian dry-cured ham, dry-cured beef, and smoked tuna) found that a 1.5 kGy dose ensured product safety and extended shelf life [49]. Another study on beef jerky treated with e-beam irradiation (0–10 kGy) observed a significant reduction in total aerobic bacteria with increasing doses, particularly at 10 kGy, which enhanced microbial safety without compromising product quality [48]. Furthermore, low-dose (below 1 kGy) e-beam irradiation under modified atmosphere packaging (100% O₂ and N₂:O₂ [2:1]) has been proposed as a viable method for reducing microbial populations or eliminating Salmonella spp. and Listeria spp. in RTE spinach [47]. New studies suggest that electron beam irradiation inhibits the growth of Rhizopus oryzae by causing structural damage and metabolic dysfunction in cells, as well as disturbed redox homeostasis [65].

3.1.3. Microwave Sterilization

Microwave sterilization, widely used in food processing for applications such as thawing, heating, blanching, pasteurization, sterilization, cooking, drying, and frying [66], offers rapid heat transfer, significantly reducing processing times compared to conventional thermal methods. Its impact on food quality primarily involves microbial and sensory characteristics. Akbar et al. found Salmonella contamination in RTE poultry during storage [46]. Microwave heating (900 W) for 90 s or more effectively eliminated the target bacteria (10⁶–10⁷ CFU/g). Peng et al. compared microwave and hot water treatments using a carrot model system, demonstrating superior color retention in microwaved carrots [41]. However, microwave technology has limitations, including uneven temperature distribution and the “edge overheating effect” [67]. Research efforts are addressing these challenges, for example, by using water as an intermediary heating step to improve uniformity and mitigate edge effects [68].

3.1.4. Radio Frequency

Radio frequency (RF) heating, a physical method employing electromagnetic waves (1–100 MHz), generates rapid and deep internal heating in food products. Generally, it is used as a thaw for frozen RTEM [69]. These waves penetrate the food matrix, interacting with ions, atoms, and molecules to produce heat. Wang et al. used a combined RF (27.12 MHz, 6 kW) and hot water treatment to successfully inactivate Staphylococcus aureus spores in RTE spicy sliced pork, achieving a 5-log reduction while maintaining desirable sensory attributes [70]. Xu et al. evaluated the effects of zinc oxide nanoparticles combined with RF heating on RTE carrots [42]. After 60 days of storage, total plate counts remained below 1000 CFU/g, and color, firmness, and carotenoid content were well preserved. Despite its potential, research on RF heating in food processing has been relatively limited, and its advantages in the RTE sector remain largely unexplored, necessitating further investigation.

3.2. Microbial Control in RTEMs Using Natural Extracts

3.2.1. Antimicrobial Activity of Natural Extracts

Perishable foods, particularly RTE meat products, are susceptible to bacterial and fungal contamination, leading to undesirable reactions that compromise flavor, odor, color, sensory qualities, and texture. To address this, in addition to incorporating sterilization techniques during RTEM processing, natural extracts can be introduced at earlier stages for antimicrobial and preservative effects. For example, bioactive compounds with antioxidant properties can be added during processing, applied as coatings, or incorporated into packaging materials to inhibit microbial growth and reduce lipid oxidation in RTE meat products [71,72]. A meta-analytic study showed that natural plant extracts significantly improved the quality of meat products, including decreased pH, increased antioxidant capacity, reduced degree of oxidation, and inhibited microbial growth [73]. In this context, plant extracts have been extensively studied and utilized due to their safety and potential as antimicrobial and antioxidant agents (

Table 4. Application of different natural extracts in the processing of RTEMs and their effect on the products.

Product	Natural Additive	Effect	Refs
All-beef hot dog	Freeze-dried Hibiscus sabdariffa flower extract	240 mg/mL was most effective in preventing or reducing Listeria monocytogenes and methicillin-resistant Staphylococcus aureus	[75]
Cooked pork balls	Grape seed and green tea extract	Samples containing green tea and grape seed extracts had lower thiobarbituric acid reactive substances, major volatile compounds, and microbial counts than sodium ascorbate samples and inhibited the formation of cholesterol oxidation products	[76]
Hot dog	Green tea (0.35%) and grape seed (0.22%)	Significant inhibited Listeria monocytogenes	[77]
Pre-made turkey ham	Galangal flower extract	Significantly inhibited Staphylococcus aureus and Listeria monocytogenes, with no adverse effects on sample color or pH	[78]
Cooked chicken	Follicular red yeast leaf ethanol extract	Inhibited Listeria monocytogenes	[79]
Chicken meatballs	Cinnamon extract	Decreased peroxide value without any effect on sensory properties	[80]
Sausages	Cinnamon essential oil	Reduced peroxide value, no effect on sensory properties	[81]
Pork sausage	Microencapsulated cornus officinalis extract	Reduced lipid oxidation in fresh pork sausage	[82]
Meat	Fruit extracts	Extend shelf life and health-promoting attributes	[83]

) [74].

Recent studies indicate that plant extracts in meat products serve beyond antimicrobial and antioxidant functions, acting as natural preservatives and pigments. The addition of fruit extracts like pomegranate seeds, acai berry leaves, and black pepper to meat products enhances antioxidant capacity and increases fiber content, improving overall product health properties [83]. Additionally, plant extracts obtained using green solvents as natural antioxidants in fresh meat products effectively scavenge free radicals, providing additional health benefits [84].

In the specific application studies, Higginbotham et al. investigated the antimicrobial activity of freeze-dried hibiscus flower extract as a rinse on all-beef frankfurters against L. monocytogenes and methicillin-resistant S. aureus (MRSA) [75]. High extract concentrations (240 mg/mL) proved the most effective in preventing or reducing contamination. Cadet et al. studied the antimicrobial efficacy of galangal flower extract (GFE) on RTE turkey ham inoculated with L. monocytogenes and S. aureus and stored at 4 °C [78]. GFE significantly inhibited both pathogens, reducing counts by 1.00 log CFU/g without adversely affecting color or pH. Furthermore, incorporating GFE into the meat mixture before cooking proved more effective than post-treatment application. An ethanolic extract of Rhodotorula mucilaginosa leaves exhibited good inhibitory activity against L. monocytogenes in cooked chicken under microwave conditions (internal temperature of 80 °C). Antimicrobial activity was enhanced when storage temperature was increased from 4 °C to 37 °C. Both low (10⁴ CFU/g) and high (10⁶ CFU/g) extract concentrations, applied via rinsing or injection, effectively reduced L. monocytogenes counts [79].

Chan et al. demonstrated that treating chicken meatballs with 200 ppm cinnamon extract under frozen storage reduced peroxide values throughout the storage period without impacting sensory characteristics [80]. Moarefian et al. showed that adding cinnamon essential oil (20 and 40 ppm) to RTE-cooked sausages reduced peroxide values without affecting sensory qualities [81]. Baldin et al. observed reduced lipid oxidation in fresh sausages containing microencapsulated jaboticaba extract (MJE) [82]. After 15 days of storage, 2% and 4% MJE effectively inhibited oxidation. However, while 2% MJE had no adverse sensory effects, 4% MJE negatively impacted color, texture, and overall acceptability. Price et al. compared the effects of grape seed and green tea extracts with sodium ascorbate on bacterial spoilage in RTE-cooked pork meatballs during refrigerated storage [76]. Samples containing green tea and grape seed extracts exhibited lower thiobarbituric acid reactive substances (TBARS) values, reduced volatile compounds, lower microbial counts, and greater inhibition of cholesterol oxidation product formation compared to sodium ascorbate samples. Combining heat treatment (65 °C, 104 s) with plant extracts and chemical preservatives synergistically inhibited L. monocytogenes growth in chicken frankfurters [77]. Thus, natural plant extracts, combined with thermal treatments, can potentially reduce reliance on chemical preservatives.

Combined with these research results, we can see that the application of natural plant extracts in RTE meat products not only helps ensure their safety and extend their shelf life but also can maintain the sensory quality and nutritional value of the products to a certain extent. These studies provide new ideas and methods for future processing of RTE meat products.

3.2.2. Natural Extracts for Nitrite Inhibition and Replacement

Sodium nitrite, a multifunctional ingredient used in food processing, enhances color, flavor, and shelf life. However, high nitrite levels are common in many RTE products, and excessive nitrite/nitrate intake poses potential cancer risks [85]. To mitigate nitrite usage, natural plant extracts with antimicrobial and antioxidant properties are being explored as alternatives, offering the added benefit of color enhancement. Plant polyphenols, widely used as antioxidants and antimicrobials, can extend the shelf life of meat products [86,87]. Their mechanisms of action include disrupting bacterial cell walls, inhibiting biofilm formation, suppressing microbial enzymes, interfering with protein regulation, altering bacterial metabolism, and inhibiting ATP and DNA synthesis. Moreover, polyphenols reduce lipid peroxidation, inhibit lipoxygenase activity, improve color stability, and minimize the degradation of salt-soluble myofibrillar proteins and sulfhydryl groups. Importantly, plant polyphenols possess strong hydrogen-donating abilities and react with nitrite under acidic conditions [86]. Studies have shown that components from various plant extracts can reduce nitrite content. For instance, non-extractable polyphenols (NEPs) from hawthorn pomace significantly reduced nitrite levels in Chinese mustard [88]. Organic peppermint essential oil and tomato pomace extract also decreased residual nitrite in sausages [89]. Furthermore, plant-derived nitrite from vegetable powders or young radish extract effectively inhibited lipid oxidation and bacterial growth in sausages [90].

Maintaining RTEM quality and safety, particularly for prefabricated vegetables, is essential in the production chain, with microbial contamination as the main challenge. Different products require specific preservation strategies. For RTEMs where nutrition and sensory qualities matter most, mild methods like autoclave treatments and plant extracts effectively eliminate microbes while preserving quality. Combined with proper packaging, these approaches enhance safety and shelf life. Long-shelf-life RTEMs benefit from irradiation and autoclave heat sterilization, providing efficient broad-spectrum protection. Selection factors include product type, production scale, and cost considerations. Large operations typically prioritize efficiency, while smaller producers focus on quality. Combining methods can optimize both nutrition and shelf life, with environmental conditions requiring careful management. Emerging technologies like microwave and RF heating offer new sterilization possibilities despite uneven heating challenges. Natural extracts provide valuable antibacterial, antioxidant, and nitrite-inhibiting properties, reducing chemical preservative needs. Future research should explore mechanisms of action, application methods, and synergistic preservation techniques to meet the growing consumer demand for healthy convenience foods.

4. Packaging Technologies and Safety Control in RTEMs

Packaging plays a vital role in RTEM safety, preserving quality, extending shelf life, and preventing contamination and pathogen transmission. Recent innovations in packaging technology offer multi-layered safety solutions for the RTEM industry, enhancing product quality, extending shelf life, and reducing environmental impact [91]. The adoption of these technologies is particularly prevalent in developed countries like those in Europe, North America, and Japan [92], highlighting the increasing importance of packaging in RTEM safety. Key packaging technologies for RTEMs include modified atmosphere packaging (MAP), functional packaging materials, and intelligent packaging (Figure 6).

4.1. Modified Atmosphere Packaging

The modified atmosphere packaging mainly includes vacuum packaging, modified atmosphere packaging, and dynamic modified atmosphere packaging (Figure 7). Vacuum packaging, a fundamental MAP technique, inhibits aerobic microbial growth by reducing oxygen levels, thereby extending shelf life. Generally, vacuum packaging, due to its exclusion of air, offers superior product quality preservation compared to conventional packaging. Siriskar et al. demonstrated that vacuum-packed RTE anchovies stored at 30–35 °C had a shelf life of several months, compared to just 5 weeks for conventionally packaged products [93]. Studies have confirmed that vacuum packaging reduces the growth rate of aerobic bacteria in RTEMs [94]. However, its effectiveness varies depending on product moisture content. For low-moisture RTEMs (e.g., baked goods), vacuum packaging can extend shelf life by 2–3 times, whereas the effect is more limited in high-moisture products [95,96]. Xu et al. found that vacuum packaging combined with ascorbic acid effectively preserved the quality of fresh-cut potatoes during storage, extending shelf life [97].

MAP for mixed gases, a more sophisticated approach, adjusts the proportions of nitrogen, carbon dioxide, and oxygen within the package to further inhibit microbial growth and extend shelf life. Stamatis et al. found that MAP extends the shelf life of mackerel compared to vacuum packaging [98]. Commonly used gas mixtures include high-oxygen (70–80% O₂/20–30% CO₂) for fresh RTE meats [99], high-nitrogen (70–80% N₂/20–30% CO₂) for fried RTE products [100], and balanced mixtures (40–45% O₂/40–45% N₂/10–20% CO₂) for mixed RTEMs. The efficacy of different gas mixtures is significantly distinct. High O₂ concentrations (>70%) inhibit enzymatic browning, prevent anaerobic fermentation, and suppress both aerobic and anaerobic microbial growth [101]. High CO₂ concentrations (>20%) effectively inhibit aerobic bacteria and mold growth, while high N₂ concentrations prevent package collapse and oxidative reactions [102].

Dynamic MAP represents a significant advancement. Yam et al. developed a smart sensor system for real-time monitoring of gas composition within the package [103]. Sandhya’s research demonstrated that dynamic MAP extends RTEM shelf life by 25–40% compared to traditional MAP [104]. Zhang et al. showed that dynamic MAP significantly improves food quality by reducing moisture loss and preserving color [105].

4.2. Functional Packaging Materials

Antimicrobial packaging, a key area of functional packaging, incorporates antimicrobial agents into packaging materials to inhibit microbial growth and maintain food quality. These agents can be natural (derived from plants, animals, or microorganisms), inorganic, or organic (e.g., organic acids and phenols) (Figure 8).

Natural antimicrobial agents offer advantages in terms of safety, non-toxicity, and efficacy. Studies have shown that plant essential oil blends, such as rosemary/thyme, can extend the shelf life of RTE meat products by 40% [106]. Dinika et al. reported that antimicrobial peptides from animal sources (e.g., lactoferrin) possess broad-spectrum activity and can be incorporated into edible film composites for shelf-life extension [107]. Iseppi et al. found that microbially derived antimicrobials (e.g., bacteriocin bacLP17) exhibit specific activity against Listeria [108].

In inorganic antimicrobial packaging, Azizi-Lalabadi et al. demonstrated the excellent broad-spectrum antimicrobial properties of nano-zinc oxide and nano-titanium dioxide composite packaging [109]. Nano-zinc oxide has been shown to preserve color, prevent spoilage, and enhance the mechanical properties of packaging materials [110]. Research indicates that nanocomposites containing 5% nanosilver and 5% TiO₂ nanoparticles exhibit strong antimicrobial activity against Escherichia coli and S. aureus [111]. Nanosilver, in particular, is a highly effective inorganic antimicrobial agent. Nano silver is added to plastic or polymer, which can significantly improve the gas barrier of packaging materials, especially for oxygen and water barrier, which helps extend the shelf life of food [112]. In addition, nanofillers such as carbon nanotubes and nanosilica can enhance the mechanical strength and toughness of packaging materials, making them more resistant to tearing and compression [113].

In organic antimicrobial packaging, Huang et al. [114] synthesized a series of novel quaternary ammonium compounds, among which dodecyl-containing compounds demonstrated the most potent and broad-spectrum activity against tested bacteria and fungi, with minimum inhibitory concentrations (MICs) ranging from 0.24 to 0.98 μg/mL. Organic acids inhibit microbial growth by lowering the pH of the microenvironment, and composite packaging systems incorporating these acids have shown good antifungal activity [115]. However, despite their rapid action and wide availability, organic antimicrobials often lack long-term efficacy and are susceptible to environmental factors. Furthermore, the potential migration of these agents into food requires further investigation [116].

4.3. Intelligent Packaging

Intelligent packaging integrates devices, sensors (mechanical, biological, electronic, chemical), and network technologies into packaging materials to monitor changes in food quality and freshness (Figure 9). However, high costs limit its widespread adoption.

Research on time–temperature indicators (TTIs) has led to the development of novel photochromic TTIs that accurately monitor the temperature history of RTEMs during storage and transport with a precision of ±0.5 °C [52]. Theofania et al. [117] reported the use of a TTI model to estimate quality degradation in RTE fresh-cut salads throughout the supply chain, enabling the prediction of remaining shelf life at any point. Furthermore, new-generation TTIs based on nanomaterials can monitor both temperature and humidity, providing comprehensive monitoring during storage and transportation [118,119].

In freshness indication technology, pH-sensitive dye-based indicators provide visual cues for RTEM freshness through color changes, achieving an accuracy of 85–90% [120]. Hanie et al. developed biosensor indicators for specific detection of pathogenic microorganisms, enhancing RTEM safety monitoring [121]. Wang et al. developed a laccase-based microcapsule time–temperature indicator (TTI) that accurately indicated spoilage in button mushrooms [55].

In intelligent traceability systems, radio frequency identification (RFID) tags use radio waves to identify and track RTE products [122]. RFID tags are well suited for food supply chain management due to their high data storage capacity (up to 1 MB) and their ability to collect real-time data wirelessly and without line-of-sight [123]. These tags can be combined with TTIs to record environmental parameters like humidity [124]. Studies have shown that companies using intelligent traceability systems experience a 40% reduction in product quality complaints and a threefold increase in traceability efficiency [124].

Packaging technology is vital for prepared dish quality and safety, protecting products from damage and contamination while preserving sensory qualities and nutrients and extending shelf life. Common technologies include vacuum, modified atmosphere, active, and intelligent packaging. Vacuum packaging inhibits aerobic microorganisms and oxidation by removing air, though it poorly protects fragile items. Modified atmosphere packaging regulates gas composition to control respiration and microbial growth, maintaining freshness. Active packaging incorporates functional substances like oxygen absorbers and antimicrobials. Intelligent packaging uses integrated sensors to monitor product status in real-time. Future packaging trends will focus on sustainability, intelligence, and functionality. Biodegradable and edible materials will reduce environmental impact. IoT and big data integration will enable traceability and quality monitoring. Research will emphasize multifunctional composite materials. Ongoing innovation will deliver safer, convenient products while supporting sustainable industry development.

5. Quality and Safety Control Systems

RTEMs face complex quality and safety risks during transportation and storage. Statistics indicate that approximately 35% of global RTEM safety incidents stem from deficiencies in transportation and storage management [125]. Establishing robust and comprehensive quality and safety control systems for these stages is crucial for industry development (Figure 10).

Ensuring the quality and safety of food products, particularly during long-distance transportation, necessitates a robust cold chain infrastructure [126]. This infrastructure is pivotal in maintaining the freshness of perishable goods and reducing waste and losses during transit [127]. For example, frozen RTEMs will deteriorate when the temperature is too high [128]. Advanced quality and safety control systems, such as intelligent cold chain systems, play a crucial role in providing optimal temperature and humidity conditions across various stages of food production, processing, transportation, storage, and sales. These systems effectively inhibit microbial activity, slow down food spoilage, and mitigate the risk of foodborne diseases [127].

Key elements of modern cold chain logistics systems include precise temperature control systems, intelligent inventory management, and humidity control. For instance, the colorimetric temperature monitoring system developed by Chu et al. and the smart temperature and humidity monitoring system designed by Chen et al. offer precise environmental control, extending the shelf life of ready-to-eat meals [129,130]. Artificial intelligence is employed in inventory management to optimize stock turnover, reduce product backlog, and adjust inventory structures based on sales forecasts, enhancing economic efficiency [131].

Humidity control is equally critical, with studies indicating that relative humidity should be maintained between 60 and 70% during transportation [132]. The integration of IoT technologies in modern logistics enables comprehensive monitoring throughout the process [133]. Additionally, the application of photocatalytic disinfection systems, air purification systems, and effective pest control measures, such as the use of insect traps and sticky mouse boards, ensures food storage safety [134,135].

Emergency management and risk prevention are integral to storage and transportation safety. The development of an improved early warning method by Geng et al. and the implementation of emergency response decision support systems provide optimized solutions in the event of emergencies, reducing response times [136]. Blockchain technology has become increasingly popular for traceability in the transportation of ready-to-eat meals, offering real-time tracking, authentication, protection, and monitoring capabilities [137].

The research and development of smart transportation containers, like those using phase change materials for adaptive multi-temperature control by Zhou et al., have significantly enhanced transportation safety [138]. Moreover, the application of rapid detection technologies has improved quality control efficiency [139]. Portable biosensors can complete pathogen detection in just 15 min, and image recognition systems based on deep learning, as demonstrated by Zhu et al., can automatically identify the spoilage characteristics of ready-to-eat meals with high accuracy [140].

In conclusion, the integration of these quality and safety control systems not only ensures the quality and safety of ready-to-eat meals but also drives the continuous development of the cold chain logistics industry. These systems underscore the importance of technological advancements in maintaining high standards of food quality and safety throughout the supply chain.

6. Conclusions and Prospects

This comprehensive review has provided a detailed analysis of the current state of technological advancements in RTEM safety and quality control, spanning the entire supply chain from raw material sourcing to consumer consumption. We have explored a wide range of innovations, including novel detection methods for contaminants, novel sterilization processes, and advanced packaging technologies. These advancements are transforming the RTEM industry, enabling the production of safer, higher-quality, and more convenient meals. However, despite the significant progress achieved, several key challenges and opportunities remain, shaping the future trajectory of this rapidly evolving sector.

One crucial area for future research lies in the development of integrated, multi-hurdle approaches to safety and quality control. Rather than relying on single interventions, combining different technologies can offer synergistic benefits and enhance overall effectiveness. For instance, integrating natural antimicrobials with modified atmosphere packaging and non-thermal sterilization techniques could provide a comprehensive strategy for minimizing microbial growth and extending shelf life while preserving product quality. This holistic approach requires further investigation into the compatibility and efficacy of different combinations, tailoring the approach to specific product types and storage conditions.

A significant challenge facing the RTEM industry is maintaining the nutritional value and sensory appeal of products throughout processing and storage. Conventional sterilization methods, while effective in eliminating pathogens, can often compromise the taste, texture, and nutrient content of meals. Therefore, future research should prioritize the development of minimal processing techniques and innovative packaging solutions that preserve the freshness, flavor, and nutritional integrity of RTEMs. This includes exploring novel non-thermal sterilization methods, such as pulsed electric fields and high-pressure processing, as well as developing active and intelligent packaging systems that can respond to changes in the product environment and maintain optimal conditions for quality preservation.