Shared kitchens are built to cut startup costs, but sharing space can also raise a food-safety question: does more sharing mean more contamination? This study finds a more complicated answer. Shared kitchens embody the shared economy by sharing communal kitchen facilities and ownership of properties, with a focus on cost reduction and high efficiency.

Their advantages include reducing initial startup costs for the food service industry and providing efficient production spaces. In the United States, the average initial startup cost is USD 475,500 for a restaurant, compared with USD 150,500 for a shared kitchen focused on takeout and delivery.

The most significant factor attributed to the downsizing of the shared kitchen market is policy regarding shared kitchens. Korea’s Food Sanitation Act previously allowed only one operator in a kitchen because of concerns over cross-contamination and food poisoning.

Shared kitchens are especially prone to cross-contamination because multiple individuals use them for food preparation. Microbiological analysis found the highest bacterial contamination on kitchen sponges, followed by draining racks and sink drains, highlighting the need for enhanced hygiene measures.

The study investigated the operational conditions of various shared-kitchen types in Korea by visiting kitchens, inspecting operations, and surveying operators. It also assessed biological and chemical hazards in prepared foods and shared-kitchen environments.

Finally, it drew insights from overseas shared-kitchen models to optimize the advantages of the system in Korea. The shared-kitchen industry was classified into open-type and separated-type shared kitchens. Open shared kitchens were divided into concurrent-use and time-division types, where multiple businesses use the kitchen at the same or different times.

Separated-type shared kitchens use individual kitchens for each business but share storage facilities and hallways. Figure one classifies shared kitchen models in Korea into open and separated types. Open kitchens include concurrent-use, where multiple users operate together, and time-division, where users access the same kitchen at different times; the chart labels these as n equals five and n equals nine.

The separated-individual type, labeled n equals sixteen, gives each business its own kitchen while sharing facilities such as storage and hallways. This framework matters because it defines the operating arrangements examined in the sanitation assessment.

Among 30 shared kitchen companies, 11 facilities were selected for analysis of facility sanitation management. Swab kits were used on hallways, door knobs, refrigerators, sinks, worktops, cutlery, and cooking clothes to monitor airborne bacteria, total bacterial count, and coliforms.

Seven products from 30 shared kitchen companies were selected to evaluate microbial and chemical hazards in prepared foods, including frozen breads, snacks, ready-to-eat salads, and sauces. Quantitative analysis of total bacterial counts, coliforms, and E. coli was conducted in all samples according to the Food Code.

For total aerobic bacteria, samples were homogenized, diluted, placed on 3M Petri films, incubated at 36 degrees Celsius for 48 hours, and counted by red colonies. For coliforms and E. coli, diluted samples were placed on E.

coli and coliform Petri films, incubated at 37 degrees Celsius for 48 hours, and counted by red and blue colonies with bubbles. Thirty shared kitchen companies were visited nationwide, and food-hygiene compliance was assessed with 128 evaluation items. The categories covered regulations, workstation and environment, hygiene management, food defense, and document management.

Three professionals from food-hygiene consulting firms in Korea conducted the evaluations, scoring compliance as zero and noncompliance as one. Table 2 presents contamination levels of hygiene-indicator bacteria and food-poisoning pathogens in 11 domestic shared-kitchen facilities.

S. aureus, B. cereus, Salmonella species, and yeast and mold were not detected in any environment, regardless of kitchen type. Very low levels of total aerobic bacteria and coliforms were detected in all environments except hallways, and contamination varied by kitchen type.

The lowest levels of total aerobic bacteria and coliforms in all environments were detected in concurrent-use shared kitchens. Table 2 reports microbial contamination across hallways, refrigerator surfaces, sinks and worktops, cutlery, and cooking clothes in three shared-kitchen types.

Total aerobic bacteria and coliforms were generally detected on facility surfaces, while yeast and mold were not detected except in hallways, where only yeast and mold were recorded. The superscript letters mark statistically significant differences, including for refrigerator interiors and cutlery, showing why contamination can vary by both location and kitchen-sharing arrangement.

Table 3 presents contamination levels of hygiene-indicator bacteria and food-poisoning pathogens in prepared food from shared kitchens. No food-poisoning pathogens were detected, and coliforms and E. coli were not detected except in two kinds of quinoa salads. Hygiene-indicator bacteria were significantly highest in salads, while bread and snack items generally showed very low microbial contamination, typically less than one log CFU per gram.

The quinoa tofu mushroom salad had total aerobic bacteria of 3.93 plus or minus 0.24 log CFU per gram and coliforms of 1.42 plus or minus 0.15 log CFU per gram. Table three reports microbial hazard measurements for foods prepared in shared kitchens, giving means and standard deviations for total aerobic bacteria and coliforms.

Total aerobic bacteria are reported for the baked items, quinoa tofu mushroom salad, and shrimp quinoa salad, while coliforms are detected only in the two quinoa salads; the remaining entries are marked “not detected.” The authors note that food-poisoning pathogens and E. coli were not detected, and that contamination levels were significantly highest in salads.

Table 4 presents chemical hazards, including pesticide residues and heavy metals, in seven prepared foods. No preservatives were detected in the cheesecake and plain scone, and total aflatoxin was not detected in peanut butter cookies. Some pesticide residues and heavy metals were detected in the two quinoa salads, and only dinotefuran, imazalil, lufenuron, and pyridalyl were detected among 320 pesticides analyzed.

The shrimp quinoa salad had the highest imazalil level at 0.068 milligrams per kilogram, while the quinoa tofu mushroom salad had the highest pyridalyl level at 0.054 milligrams per kilogram. Table four reports chemical hazards across seven foods from shared kitchens, including preservatives, total aflatoxin, pesticide residues, heavy metals, and tar color.

Most entries are not detected or not tested, while the two quinoa salads contain measured residues of dinotefuran, imazalil, lufenuron, and pyridalyl, along with cadmium and lead. This matters because it identifies which prepared foods require closer chemical-safety monitoring.

In the hygiene inspection survey, a score of zero meant compliance and one meant noncompliance, so a higher average score represented poorer management. The concurrent-use type scored lower than the other two types in workstation and environment and hygiene management, although no significant difference was observed among the types in those categories.

For legal compliance, the differences among all three types were significant, and the separated-individual type had the highest score at 2.81 plus or minus 1.72, followed by time-division at 2.11 plus or minus 2.09 and concurrent-use at 0.60 plus or minus 0.55. In document management, concurrent-use and time-division scored significantly lower than separated-individual, with scores of 2.20 plus or minus 2.05 and 1.89 plus or minus 2.71, compared with 5.25 plus or minus 2.74.

Table five reports hygiene-inspection scores for thirty shared-kitchen businesses, grouped as concurrent-use, time-division, and separated-individual kitchens. Because zero means compliance and one means noncompliance, higher average scores indicate poorer management; the table covers regulation, workstation and environment, hygiene management, food defense, and document management.

Superscript letters mark statistically significant differences within categories at p less than zero point zero five, making the visual useful for identifying where kitchen type is associated with different hygiene conditions. Among the major operational challenges, economic cost received the highest response, followed by hygiene management of shared-kitchen users.

Operators reported that mandatory insurance, frequent hygiene training, inspections, and cleaning and disinfection were major operational economic challenges compared with regular restaurants. Although shared kitchens initially gained attention for reducing startup costs through business incubation and kitchen sharing, current regulations increase operational costs and reduce market competitiveness in Korea.

The number of shared-kitchen businesses increased from 200 in 39 states in 2016 to 600 in 48 states by 2020. Food-service facilities are regulated by local governments in each state, and food-service businesses are managed by local health departments.

The key laws and regulations of shared kitchens in New York State and Chicago were compared in the United States. HACCP is not mandatory for shared kitchens in Korea, but a product produced in a shared kitchen must be certified if it falls into a category requiring HACCP certification.

In the European Union, liability insurance is recommended rather than mandatory, unlike in Korea. Table seven compares shared-kitchen terminology and regulatory requirements across New York, Chicago, Georgia, the European Union, the United Kingdom, France, China, India, and Korea.

It covers hygiene-manager requirements, HACCP application, and insurance: for example, Korea lists a mandatory hygiene manager and mandatory HACCP for specific food sectors, while insurance is marked mandatory only for Korea. The comparison matters because the authors discuss differing regulatory approaches and the need to assess liability insurance and small-scale HACCP for stable shared-kitchen operations.

Concurrent-use and time-division open shared kitchens showed significantly lower microbial and chemical hazards than separated-individual kitchens. Hygiene inspection scores for hygiene management, workplace environment, and regulatory compliance were significantly lower in concurrent-use open shared kitchens than in separated-individual kitchens, confirming better hygiene management in open shared kitchens.

Frequent facility cleaning and disinfection, shorter hygiene inspection cycles, and regular hygiene training became economic burdens on shared-kitchen operations. The regulation comparison suggests that food-safety responsibilities of operators and users must be imposed equally, while small-scale HACCP systems can be suggested to elevate consumer safety consciousness.

The paper also suggests easing regulatory constraints through menu simplification and standardization, as exemplified by practices in China. The open shared-kitchen models showed lower measured hazards and better hygiene-management scores, yet regulation-related costs burden operators.

The paper argues for safety rules that protect consumers without undermining the model’s economic advantages.