Frozen Vegetable and Potato Consumption and Handling Practices – Minnesota, 2023

Abstract

Frozen vegetables are considered a not ready-to-eat product and are packaged with cooking and safe handling instructions. Surveys have demonstrated that consumers perceive frozen vegetables to be relatively safe, which might make consumers less likely to follow cooking and safe handling instructions. While studies have demonstrated that consumer handling of frozen vegetables is suboptimal, there is a need to characterize handling practices for a variety of vegetable types. The objective of this study was to assess consumption frequency and preparation practices for a variety of prepackaged frozen vegetables and frozen potatoes. We conducted a survey at the 2023 Minnesota State Fair and received 1,719 completed surveys from Minnesota residents aged ≥18 years. The vast majority consumed frozen vegetables and frozen potatoes in the previous year (91.3% and 80.1%, respectively). Overall, 15.7% of respondents reported consuming at least one frozen vegetable type raw, while raw frozen potato consumption was rare (n = 3 respondents). Among nine vegetable types, leafy greens and carrots were consumed raw more often (38.4% and 17.6%, respectively). Among those who reported always following cooking instructions for leafy greens, 36.2% of respondents reported consuming them raw. These findings provide insight into which frozen vegetables might pose a higher risk given consumer preparation practices.

Each year, six major foodborne pathogens – Campylobacter spp., Clostridium perfringens, invasive Listeria monocytogenes, norovirus, non-typhoidal Salmonella, and Shiga-toxin-producing E. coli – are estimated to cause 9.9 million domestically acquired illnesses in the United States (Scallan Walter et al., 2025). In recent years, frozen vegetables have been implicated in outbreaks caused by Salmonella (Denich et al., 2025; Kääriäinen et al., 2022) and L. monocytogenes (Madad et al., 2023; Sarno et al., 2021). Although rare, causing approximately 1,250 domestically acquired infections each year (Scallan Walter et al., 2025), L. monocytogenes is an important foodborne pathogen because it has a high case-fatality rate (U.S. Food and Drug Administration, 2012). While L. monocytogenes outbreaks associated with frozen vegetables do not typically involve large numbers of cases clustered by space or time (Madad et al., 2023; Sarno et al., 2021), the outbreaks can be prolonged because of the potential for persistent contamination of food manufacturing environments (U.S. Food and Drug Administration, 2012), widespread product distribution, and the long shelf life of the products.

The persistence of L. monocytogenes in manufacturing environments makes it a particular concern for frozen food production. A study in England found that L. monocytogenes was present in 10% of frozen vegetables in retail and catering premises (Willis et al., 2020). In a study to assess the lot-level risk of Listeriosis in frozen vegetables, the authors found that with a low-level of contamination, the role of consumer behaviors is critical for understanding the risk to consumers (Zoellner et al., 2019). Although L. monocytogenes does not grow in foods that are frozen, frozen foods may pose a risk if they are improperly thawed or not cooked before being consumed (Kataoka et al., 2017). The European Food Safety Authority found that the public health risk posed by blanched frozen vegetables is lower than for ready-to-eat (RTE) food categories such as soft and semi-soft cheese, smoked fish, and sausage; however, the risk of illness was greater if the frozen vegetables were consumed uncooked compared to cooked (EFSA Panel on Biological Hazards (BIOHAZ) et al., 2020).

Consumers perceive frozen foods to be relatively safe. A 2019 U.S. Food and Drug Administration (FDA) survey found that 40% of respondents said that they think it is not at all likely for uncooked frozen packaged vegetables to contain bacteria or other germs that could make people sick (Lando et al., 2 021). Our previous findings demonstrated that only canned foods were perceived to be safer than frozen foods compared to fresh foods and food from restaurants (Edmundson et al., 2026). These perceptions may affect consumer awareness that frozen vegetables need to be cooked. In a 2022 survey, only 63.5% of respondents agreed with the statement that “prepackaged frozen vegetables need to be fully cooked before consuming them” (Canning et al., 2024). With both RTE and not ready-to-eat (NRTE) frozen food products available in the market, consumers may not be aware of the difference. Frozen vegetables and frozen potatoes are generally considered NRTE foods and include cooking instructions and safe food handling guidance on the packaging (U.S. Department of Agriculture Food Safety and Inspection Service, 2019; U.S. Department of Agriculture Food Safety and Inspection Service, 2020); however, consumers sometimes thaw and consume frozen vegetables without following package cooking instructions. In two recent frozen vegetable outbreaks, investigators suspected that thawing and eating frozen vegetables, such as green peas and corn, without cooking or heating may have contributed to illnesses (Madad et al., 2023; Sarno et al., 2021). The perception of the relative safety of frozen vegetables might have made consumers less likely to follow cooking and safe handling instructions on these products.

Previous consumer behavior studies have assessed compliance with cooking instructions for frozen vegetables. In a 2019 FDA survey, only 41% of respondents reported looking at cooking instructions for frozen vegetables every time they make them (Lando et al., 2021). In a survey of over 3,000 respondents, 8.7% reported ever consuming frozen vegetables raw and these respondents were less likely to agree that prepackaged frozen vegetables need to be cooked before consumption compared to respondents who only cooked frozen vegetables (Canning et al., 2024). While these studies demonstrate that consumer compliance with frozen vegetable cooking instructions is suboptimal, there is a need to characterize consumer preparation practices for a variety of frozen vegetables and frozen potatoes, in order to inform strategies for reducing the risk of foodborne illness from these products. The objective of this study was to assess the consumption frequency and preparation practices of frozen vegetables and frozen potatoes.

Methods

Target population and sampling strategy.

We conducted a survey at the 2023 Minnesota State Fair in the Driven to Discover (D2D) Research Facility (Edmundson et al., 2026). The University of Minnesota Driven 2 Discover (D2D) Research Facility allows researchers to conduct studies during the twelve days of the fair. Up to ten studies can be conducted concurrently during each study shift and two shifts run per day. Researchers can request the number of shifts they would like to participate in prior to the fair. In 2023, more than 1.8 million people attended the Minnesota State Fair and 55,000 visited the D2D Research Facility (Demerath et al., 2024). In addition to completing human subjects research training, prior to the fair, volunteers participated in a 2-h training that discussed data collection considerations at the fair and study-specific information. For our study, volunteers recruited participants in front of and inside the D2D Research Facility over six 5.5–6.5-h shifts during August 24 – August 31, 2023. A sign was posted in front of the research bay that included the name of the study (“What’s in Your Freezer?”) and the eligibility criteria. Participants were eligible if they were Minnesota residents aged ≥18 years. Participants were asked to self-report that they met the eligibility criteria.

Informed consent.

After confirming their eligibility, participants were verbally given an overview of the informed consent and presented with written consent on tablets. Participants completed the survey in English individually on tablets. The study was reviewed and approved by the University of Minnesota Institutional Review Board.

Data collection instrument.

We used Research Electronic Data Capture (REDCap) to administer a 10–15-minute survey to identify frozen food consumption and preparation practices (Suppl 1). Volunteer data collectors pilot-tested the survey questions prior to the data collection period. Participants were asked to rank four categories of food by how risky/likely to be contaminated with germs they are: fresh foods, frozen foods, canned foods, and food from restaurants. Consumption frequency in the last year by food category was assessed as “Never,” “Every few months,” “Monthly,” “Weekly,” or “Daily.” We further categorized these as “Never” vs. “Ever” and “Monthly or less” vs. “Weekly/daily.” If participants indicated consuming smoothies, prepackaged frozen stuffed breaded chicken products, prepackaged frozen vegetables, or prepackaged frozen potato products, they were directed to commodity-specific modules. For frozen vegetables, participants were asked about consumption of nine types of frozen vegetables: carrots, broccoli, corn, peas, cauliflower, green beans, edamame, leafy greens, and other vegetables. For frozen potatoes, participants were asked about seven categories of frozen potatoes: french fries, potato tots, potato wedges, shredded potatoes, diced potatoes, hashbrown patties, and mashed potatoes. For each frozen vegetable and frozen potato item, participants were asked how often they follow cooking instructions on the packaging (“Always,” “Sometimes,” and “Never”) and how they most often prepared each item (“Thaw and eat without cooking,” “Microwave,” “Stove, “Oven,” “Air fryer,” “Toaster oven,” “Toaster,” “Slow cooker,” “Grill,” “Combined slow cooker/pressure cooker,” or “Rice cooker”). For frozen vegetables, participants could also select “Eat frozen and raw” or “Add frozen to blender/food processor” as a preparation method. Raw consumption was defined as reporting preparing items as “Thaw and eat without cooking,” “Eat frozen and raw,” or “Add frozen to blender/food processor.” Raw consumption was further subcategorized as “Eat frozen” or “Eat thawed”.

Demographics for study participants were collected, including age group (18–44 years; 45–64 years; or ≥65 years), gender (man; woman; nonbinary or other), and education (High school diploma/GED or less; some college or associate’s degree; bachelor’s/4-year degree; or graduate or professional degree).

Data analyses.

We calculated descriptive statistics for consumption as “Never,” “Ever,” and frequency if consumed in the last year (“Monthly or less” and “Weekly/Daily”) for frozen vegetables and potatoes across demographic categories. We calculated the number of vegetable and potato types reported and categorized them as 0 types, 1–2 types, 3–4 types, and 5 or more types. The number and types of frozen vegetable categories and frozen potato categories consumed were calculated and compared by frequency of consumption (for number) and age group (number and type). Following cooking instructions across frozen vegetables or potato consumption was compared across age groups. Preparation methods (cooked, frozen, thawed) for the three vegetables most often reported as consumed raw were compared by age group (18–64 years vs. ≥65 years). Comparisons across frequency of consumption and age groups were conducted using Pearson’s chi-squared tests. A Cochrane-Armitage test for trend was conducted to assess whether there was a linear trend in ranking frozen food from most risky (1) to least risky (4) and consumption of raw frozen vegetables in the previous year. Statistical significance for Pearson’s chi-squared tests and the Cochrane-Armitage test for trend was set at p value < 0.05. Analyses were conducted in SAS version 9.4 (SAS Institute).

Results

Frozen vegetable consumption.

Overall, 1,569 (91.3%) of 1,719 respondents reported consuming frozen vegetables in th e previous year (Table 1). Among these respondents, 57.0% (n = 895) consumed them monthly or less and 43.0% (n = 674) consumed them weekly or daily. Consumption of frozen vegetables in the previous year was high across all age groups, ranging from 92.5% of respondents aged 45–64 years to 89.8% of respondents aged 18–44 years. Respondents aged ≥65 years had the highest proportion of weekly or daily consumption (48.7%, n = 187) among those who ate frozen vegetables in the last year, while respondents aged 45–64 years were least likely to report consuming frozen vegetables weekly or daily (39.8%, n = 177) (p value < 0.05).

Table 1.

Demographic characteristics overall and for frozen vegetable consumption overall and by frequency – Minnesota, 2023

	Overall		Never frozen vegetables		Any frozen vegetables		Monthly or Less		Weekly/Daily
	n	%a	n	% a	N	% a	n	% a	n	% a
Overall	1719	100.0%	130	7.6%	1569	91.3%	895	57.0%	674	43.0%
Age b
18–44	548	37.9%	53	9.7%	492	89.8%	282	57.3%	210	42.7%
45–64	481	33.2%	33	6.9%	445	92.5%	268	60.2%	177	39.8%
>65	418	28.9%	32	7.7%	384	91.9%	197	51.3%	187	48.7%
No response	272		12		248		148		100
Gender
Man	511	30.2%	62	12.1%	439	85.9%	255	58.1%	184	41.9%
Woman	1164	68.8%	66	5.7%	1090	93.6%	623	57.2%	467	42.8%
Nonbinary or other	17	1.0%	0	0.0%	17	100.0%	8	47.1%	9	52.9%
No response	27		2		23		9		14
Education
High school diploma/GED or less	149	8.9%	19	12.8%	127	85.2%	66	52.0%	61	48.0%
Some college/Associate’s degree	355	21.1%	24	6.8%	328	92.4%	185	56.4%	143	43.6%
Bachelor’s/4-year degree	592	35.2%	48	8.1%	538	90.9%	311	57.8%	227	42.2%
Graduate or professional degree	584	34.8%	36	6.2%	545	93.3%	315	57.8%	230	42.2%
No response	39		3		31		18		13

^aPercentage calculations do not include “no response”.

^bStatistically significant across frequency (monthly or less vs. weekly/daily) at p value < 0.05.

Frozen potato consumption.

Overall, 1,377 respondents (80.1%) reported consuming frozen potatoes in the previous year (Table 2). Among these respondents, 79.5% (n = 1095) consumed them monthly or less and 20.5% (n = 282) consumed them weekly or daily. Any frozen potato consumption in the previous year was highest among respondents aged 45–64 years (83.2%, n = 400) and lowest among respondents aged ≥65 years (74.9%, n = 313). Respondents aged ≥65 years also had the lowest proportion of weekly or daily consumption (17.9%, n = 56) among those who ate frozen potatoes in the last year.

Table 2.

Demographic characteristics for frozen potato consumption overall and by frequency – Minnesota, 2023

	Never Frozen Potatoes		Any Frozen Potatoes		Monthly or Less		Weekly/Daily
	n	% a	n	% a	N	% a	n	% a
Overall	320	18.6%	1377	80.1%	1095	79.5%	282	20.5%
Age
18–44	103	18.8%	441	80.5%	335	76.0%	106	24.0%
45–64	77	16.0%	400	83.2%	324	81.0%	76	19.0%
>65	100	23.9%	313	74.9%	257	82.1%	56	17.9%
No response	40		223		179		44
Gender
Man	104	20.4%	395	77.3%	302	76.5%	93	23.5%
Woman	205	17.6%	952	81.8%	774	81.3%	178	18.7%
Nonbinary or other	5	29.4%	11	64.7%	8	72.7%	3	27.3%
No response	6		19		11		8
Education
High school diploma/GED or less	25	16.8%	119	79.9%	88	73.9%	31	26.1%
Some college/Associate’s degree	39	11.0%	314	88.5%	244	77.7%	70	22.3%
Bachelor’s/4-year degree	113	19.1%	471	79.6%	382	81.1%	89	18.9%
Graduate or professional degree	137	23.5%	443	75.9%	359	81.0%	84	19.0%
No response	6		30		22		8

^aPercentage calculations do not include “no response”.

Number of frozen vegetable and frozen potato types consumed.

More than half (59.5%, n = 934) of respondents who reported eating frozen vegetables in the past year reported consuming 3 or more of the nine vegetable types (Table 3). Respondents who reported more frequent consumption (weekly/daily) were more likely to report consuming 5 or more categories of frozen vegetables (42.6%, n = 287) compared to monthly or less consumers (21.6%, n = 193, p value < 0.05). In keeping with respondents aged ≥65 years reporting the highest proportion of weekly or daily frozen vegetable consumption across age groups (Table 1), they also had the greatest proportion reporting consuming 5 or more types (Table 3). For those aged 18–44 years and 45–64 years, the greatest proportion of each age group reported eating 1–2 vegetable types.

Table 3.

Number of types of frozen vegetables and frozen potatoes consumed overall and by reported frequency of consumption and age group – Minnesota, 2023

	Overall		Monthly or Less		Weekly/Daily		18–44 years		45–64 years		≥65 years
	n	%					n	%	n	%	n	%
Vegetable Consumption	1569	100.0%	895	57.0%	674	43.0%	492	37.2%	445	33.7%	384	29.1%
Number of Vegetable Types Consumed a
0	115	7.3%	88	9.8%	27	4.0%	43	8.7%	31	7.0%	21	5.5%
1 to 2	520	33.1%	369	41.2%	151	22.4%	187	38.0%	159	35.7%	94	24.5%
3 to 4	454	28.9%	245	27.4%	209	31.0%	141	28.7%	124	27.9%	124	32.3%
5 or more	480	30.6%	193	21.6%	287	42.6%	121	24.6%	131	29.4%	145	37.8%
Potato Consumption	1377	100.0%	1095	79.5%	282	20.5%	441	38.2%	400	34.7%	313	27.1%
Number of Frozen Potato Types Consumed a
0	178	12.9%	152	13.9%	26	9.2%	58	13.2%	38	9.5%	49	15.7%
1 to 2	751	54.5%	623	56.9%	128	45.4%	249	56.5%	216	54.0%	158	50.5%
3 to 4	331	24.0%	247	22.6%	84	29.8%	103	23.4%	109	27.3%	69	22.0%
5 or more	117	8.5%	73	6.7%	44	15.6%	31	7.0%	37	9.3%	37	11.8%

^aStatistically significant across frequency (monthly or less vs. weekly/daily) and age group at p value < 0.05.

More than one-half (54.5%, n = 751) of respondents who reported consuming frozen potatoes consumed only 1 or 2 of the 7 types. As with frozen vegetables, respondents who reported consuming frozen potatoes weekly or daily were more likely to report consuming 5 or more categories of frozen potatoes (15.6%, n = 44) compared to monthly or less consumers (6.7%, n = 73, p value < 0.05). However, respondents aged ≥65 years reported both the lowest percentage of consuming frozen potatoes weekly or daily (17.9%, n = 56) and the highest percentage of consuming 5 or more types of frozen potatoes (11.8%) compared to respondents aged 45–64 years (9.3%) or respondents aged 18–44 years (7.0%) (p value < 0.05).

Frozen vegetables and frozen potato types.

The most consumed types of frozen vegetables were corn (61.0%), broccoli (57.7%), peas (53.1%), carrots (43.1%), and green beans (41.6%) (Table 4). The least commonly consumed frozen vegetables were cauliflower (28.2%), leafy greens (28.2%), edamame (18.2%), and other single vegetables (14.5%). Differences in consumption were observed across age groups, with respondents aged ≥65 years having the highest percentages of consumption for broccoli, corn, peas, cauliflower, green beans, leafy greens, and other single vegetables (p value < 0.05 for all). Although not statistically significant, reporting consuming frozen edamame in the previous year decreased with age, ranging from 21.1% of respondents aged 18–44 years to 15.6% of respondents aged ≥65 years. Among all respondents who reported consuming frozen vegetables in the previous year, 15.7% (n = 247) reported consuming at least one vegetable type raw most often.

Table 4.

Types of frozen vegetables and potatoes consumed overall and by age group – Minnesota, 2023

	Overall		18–44 years		45–64 years		≥65 years
	N	%	n	%	n	%	n	%
Vegetable Consumption	1569	100.0%	492	31.4%	445	28.4%	384	24.5%
Vegetable Type
Carrots	677	43.1%	204	41.5%	178	40.0%	172	44.8%
Broccolia	905	57.7%	276	56.1%	242	54.4%	240	62.5%
Corna	957	61.0%	281	57.1%	276	62.0%	255	66.4%
Peasa	833	53.1%	226	45.9%	230	51.7%	254	66.1%
Cauliflowera	443	28.2%	112	22.8%	134	30.1%	126	32.8%
Green beansa	652	41.6%	167	33.9%	188	42.2%	201	52.3%
Edamame	285	18.2%	104	21.1%	72	16.2%	60	15.6%
Leafy greensa	443	28.2%	107	21.7%	125	28.1%	132	34.4%
Other vegetablesa	228	14.5%	49	10.0%	68	15.3%	74	19.3%
Any rawb	247	15.7%	66	13.4%	79	17.8%	64	16.7%
Potato Consumption	1377	100.0%	441	32.0%	400	29.0%	313	22.7%
Frozen Potato Type
French friesa	843	61.2%	290	65.8%	266	66.5%	160	51.1%
Potato tots	788	57.2%	239	54.2%	243	60.8%	184	58.8%
Potato wedges	160	11.6%	53	12.0%	48	12.0%	37	11.8%
Shredded potatoesa	458	33.3%	109	24.7%	161	40.3%	122	39.0%
Diced potatoes	193	14.0%	49	11.1%	65	16.3%	51	16.3%
Hashbrown patties	365	26.5%	114	25.9%	107	26.8%	92	29.4%
Mashed potatoesa	126	9.2%	30	6.8%	42	10.5%	40	12.8%

^aStatistically significant across age group at p value < 0.05.

^bRaw consumption for frozen vegetables is defined as reporting preparing items as “thaw and eat without cooking,” “eat frozen and raw,” or “add frozen to blender/food processor”.

Frozen potato types consumed.

French fries (61.2%) and potato tots (57.2%) were the most frequently consumed types of frozen potatoes. One-third or fewer of respondents who reported consuming frozen potatoes reported consuming frozen shredded potatoes (33.3%), hashbrown patties (26.5%), diced potatoes (14.0%), potato wedges (11.6%), and mashed potatoes (9.2%). Differences in consumption were observed across age groups, with the highest percentage of consumption for french fries (65.8%) and the lowest consumption for shredded potatoes (24.7%) among respondents aged 18–44 years, and the highest percentage of consumption for mashed potatoes (12.8%) among respondents aged ≥65 years (p < 0.05 for all).

Preparation method used most often.

For all frozen vegetables except leafy greens, the cooking appliance used most often was a microwave, followed by a stove, with greater than 55% of respondents reporting using one of these two appliances most often (Table 5). The most common cooking appliance was a stove for leafy greens (40.2%, n = 139) and other vegetables (32.9%, n = 56). Among all vegetable types, leafy greens were most often reported to be consumed raw (38.4%, n = 133), followed by carrots (17.6%, n = 93) and other vegetables (14.7%, n = 25).

Table 5.

Preparation method used most often for frozen vegetables and potatoes – Minnesota, 2023

	Microwave		Stove		Oven		Air Fryer		Other		Consumed Rawa
	n	%	n	%	n	%	n	%	n	%	n	%
Vegetables
Carrots (n = 529)	212	40.1%	167	31.6%	33	6.2%	4	0.8%	20	3.8%	93	17.6%
Broccoli (n = 754)	388	51.5%	233	30.9%	62	8.2%	18	2.4%	19	2.5%	34	4.5%
Corn (n = 803)	407	50.7%	306	38.1%	26	3.2%	2	0.2%	40	5.0%	22	2.7%
Peas (n = 695)	347	49.9%	275	39.6%	23	3.3%	2	0.3%	9	1.3%	39	5.6%
Cauliflower (n = 349)	154	44.1%	116	33.2%	34	9.7%	11	3.2%	8	2.3%	26	7.4%
Green beans (n = 533)	251	47.1%	223	41.8%	28	5.3%	7	1.3%	10	1.9%	14	2.6%
Edamame (n = 239)	122	51.0%	77	32.2%	5	2.1%	6	2.5%	4	1.7%	25	10.5%
Leafy greens (n = 346)	46	13.3%	139	40.2%	20	5.8%	2	0.6%	6	1.7%	133	38.4%
Other vegetables (n = 170)	52	30.6%	56	32.9%	23	13.5%	3	1.8%	11	6.5%	25	14.7%
Frozen Potatoes
French fries (n = 730)	16	2.2%	22	3.0%	335	45.9%	329	45.1%	26	3.6%	2	0.3%
Potato tots (n = 684)	9	1.3%	32	4.7%	377	55.1%	232	33.9%	33	4.8%	1	0.1%
Potato wedges (n = 111)	1	0.9%	13	11.7%	48	43.2%	43	38.7%	6	5.4%	0	0.0%
Shredded potatoes (n = 377)	2	0.5%	234	62.1%	110	29.2%	14	3.7%	17	4.5%	0	0.0%
Diced potatoes (n = 148)	4	2.7%	72	48.6%	51	34.5%	12	8.1%	9	6.1%	0	0.0%
Hashbrown patties (n = 286)	11	3.8%	100	35.0%	59	20.6%	67	23.4%	49	17.1%	0	0.0%
Mashed potatoes (n = 75)	44	58.7%	20	26.7%	8	10.7%	1	1.3%	1	1.3%	1	1.3%

^aRaw consumption for frozen vegetables is defined as reporting preparing items as “thaw and eat without cooking,” “eat frozen and raw,” or “add frozen to blender/food processor.” Raw consumption for frozen potatoes is defined as reporting preparing items as “thaw and eat without cooking”.

The cooking appliances used most often for french fries, potato tots, and potato wedges were ovens or air fryers, with ≥82.0% of respondents reporting using one of these two appliances. For shredded potatoes, the most common appliances were stove (62.1%, n = 234) or oven (29.2%, n = 110). For diced potatoes, the most common appliances were stove (48.6%, n = 72) and oven (34.5%, n = 51). For hashbrown patties, the most common appliances were stove (35.0%, n = 100), air fryer (23.4%, n = 67), and oven (20.6%, n = 59). More than half (58.7%, n = 44) of respondents who consumed mashed potatoes in the previous year reported using the microwave to prepare them.

Following cooking instructions on packaging.

Among the nine frozen vegetable types, more than half of respondents reported always following cooking instructions for 7 of the vegetable types: edamame (59.7%, n = 151), broccoli (57.6%, n = 451), green beans (55.3%, n = 306), corn (53.9%, n = 447), cauliflower (53.4%, n = 195), carrots (52.2%, n = 291), and peas (52.2%, n = 380) (Table 6). Reporting always following cooking instructions was lowest for leafy greens (42.1%, n = 152). Among respondents who reported always following cooking instructions for leafy greens, more than one-third (36.2%, n = 55) reported consuming them raw most often. Carrots had the second highest proportion of raw consumption among those who reported always following cooking instructions (9.6%, n = 28). Across age groups, there were no significant differences in reporting following cooking instructions (Suppl 2) except for leafy greens (p value < 0.05). Respondents aged 18–44 years and 45–64 years more often reported always following cooking instructions (50.0% and 47.1%, respectively) for leafy greens than respondents aged ≥65 years (35.8%).

Table 6.

Reporting always following cooking instructions and raw consumption for frozen vegetables – Minnesota, 2023

	Always follow cooking instructions		Consumed Rawa		Consumed rawa among those reporting always follow instructions
	n	%	n	%	N	%
Vegetables
Carrots	291	52.2%	93	17.6%	28	9.6%
Broccoli	451	57.6%	34	4.5%	15	3.3%
Corn	447	53.9%	22	2.7%	8	1.8%
Peas	380	52.2%	39	5.6%	9	2.4%
Cauliflower	195	53.4%	26	7.4%	10	5.1%
Green beans	306	55.3%	14	2.6%	7	2.3%
Edamame	151	59.7%	25	10.5%	11	7.3%
Leafy greens	152	42.1%	133	38.4%	55	36.2%
Other vegetables	83	46.4%	25	14.7%	4	4.8%

^aRaw consumption for frozen vegetables is defined as reporting preparing items as “thaw and eat without cooking,” “eat frozen and raw,” or “add frozen to blender/food processor”.

Consumption of raw frozen potatoes was rare. Only two respondents reported eating french fries and one respondent reported eating mashed potatoes most often by thawing them and eating them without cooking (Table 5). One of the respondents who reported eating raw french fries also reported consuming raw potato tots.

Preparation for top 3 vegetables consumed raw:

The three vegetables most consumed raw were leafy greens, carrots, and other vegetables. For each of these vegetables, eating them frozen was reported more frequently than eating them thawed (Suppl 3). There were differences in preparation method for leafy greens across age groups, with older respondents reporting cooking leafy greens more often compared to respondents aged 18–64 years (71.6% vs. 56.1%, respectively; p value < 0.05). Older respondents were also less likely to report eating leafy greens frozen (16.7% vs. 27.0%, respectively) or thawed (11.8% vs. 16.9%, respectively) compared to respondents aged 18–64 years. Older adults were more likely than respondents aged 18–64 years to report consuming carrots (11.8% vs. 6.6.%, respectively) and other vegetables (10.0% vs. 4.3%, respectively) thawed.

Ranking of frozen food safety and consuming frozen vegetables raw:

Among all respondents, reporting consuming frozen vegetables raw demonstrated a statistically significant (p value < 0.05) inverse relationship with ranking as most risky to least risky (Suppl 4). Five respondents (11.4%) reported consuming frozen vegetables raw in the previous year among those who ranked frozen vegetables as most risky/likely to be contaminated with germs, compared to 17.2% (n = 102) of respondents who ranked them least risky.

Discussion

Frozen vegetable and frozen potato consumption was common among Minnesota adults, with 91.3% reporting any frozen vegetable consumption in the last year and 80.1% reporting any frozen potato consumption in the last year. Adults aged ≥65 years reported the highest weekly or daily frozen vegetable consumption and the lowest weekly or daily frozen potato consumption. Older adults were also more likely to report consuming more types of frozen vegetables and frozen potatoes compared to younger age groups. While Listeria infection is rare, certain populations, including adults aged ≥65 years, are at increased risk for Listeria infection (Centers for Disease Control and Prevention, 2025). Recent studies have demonstrated that older adults do not perceive themselves to be at higher risk than other individuals (Evans et al., 2020; Kavanaugh et al., 2021; U.S. Food and Drug Administration). In our study, older adults reported consuming frozen vegetables frequently and were not less likely to report always following cooking instructions compared to other age groups, except for leafy greens. However, because age is a risk factor for Listeria infection, our findings suggest that older adults may be increasing their risk of illness due to preparation practices for most frozen vegetables.

In our study, reporting eating frozen vegetables raw, without heating or cooking, was not uncommon, with 15.7% of respondents (n = 247) who ate frozen vegetables consuming at least one frozen vegetable type raw. This is slightly higher than a recent national survey that reported 8.7% of respondents reported ever consuming raw frozen vegetables, although they did not account for differences in raw consumption across vegetable types (Canning et al., 2024). Our study found that reporting consuming frozen vegetables raw most often varied across vegetable types, ranging from 2.6% for green beans to 38.4% for leafy greens. This finding demonstrates which frozen vegetables consumers may be amplifying the risk of illness based on how they are preparing them (raw vs. cooked). While frozen leafy green consumption among respondents was relatively low, with only 28.2% of respondents who reported consuming frozen vegetables in the last year reporting consuming them, it is notable that more than one-third (36.2%) of respondents who reported always following cooking instructions for leafy greens reported most often preparing them without cooking or heating them. This suggests that people may not be aware of the cooking instructions or may be disregarding them.

This study further evaluated preparation practices for the three vegetables most commonly consumed raw to demonstrate how consumers may potentially be increasing their risk of illness through thawing. If frozen vegetables reach temperatures that support Listeria growth through thawing without thorough cooking before consumption, this can increase the risk of illness (EFSA Panel on Biological Hazards (BIOHAZ) et al., 2020). Furthermore, research has demonstrated that heat treatment during production through blanching may result in frozen vegetable products where Listeria may grow better during storage after thawing (EFSA Panel on Biological Hazards (BIOHAZ) et al., 2020). As such, thawing may further amplify the risk of illness if frozen vegetables are not cooked properly after thawing. For the three vegetables most frequently consumed raw, respondents aged 18–64 were more likely to report consuming leafy greens thawed than older respondents. However, older respondents reported consuming carrots or other vegetables thawed more than respondents aged 18–64 years. While raw consumption of frozen vegetables other than leafy greens was relatively low, overall, these findings further clarify which vegetables may pose a greater risk across age groups due to consumer preparation practices. By contrast to frozen vegetables, only 3 of the 1,377 respondents (0.2%) who reported consuming frozen potatoes reported most often consuming them raw. These findings suggest that consumers may amplify the risk of illness from frozen vegetables, particularly leafy greens, through preparation practices, but not for frozen potatoes.

In our study, air fryers were commonly used to prepare frozen potatoes, but not frozen vegetables. For french fries, air fryer use was as common as using ovens (45.1% vs. 45.9%, respectively). Air fryers, which operate by circulating hot air uniformly around food, have emerged as a technological advancement to obtain the same sensory features as frying, but with considerably less oil (Andrés et al., 2013). Air fryers represented a $1.07 billion industry in 2025, and it is expected to grow to $1.89 billion by 2032 (Data Bridge Market Research, 2025). A study using NRTE breaded stuffed chicken products showed that both basket-type air fryers and oven-type air fryers were effective at reducing Salmonella contamination; however, cooking times to achieve these reductions varied across air fryer type (Okur et al., 2025). With air fryers becoming a popular household cooking appliance, there is a need to ensure there are validated cooking instructions for a variety of products and air fryer types.

Our study had a few notable limitations. First, our study represents a convenience sample of people who visited the D2D Research Facility during our six shifts at the 2023 Minnesota State Fair, which may limit the generalizability of the study. Notably, the study sample skewed toward older populations, with nearly half of the respondents (48.6%) aged ≥55 years (Edmundson et al., 2026). Additionally, respondents were highly educated, with 70.0% having a bachelor’s degree or more. A recent study found that those at higher education levels are more likely to report ever preparing or consuming frozen vegetables raw (Canning et al., 2024), which might have contributed to why raw consumption in our study was higher than in previous studies. While we assessed the frequency of consumption for frozen vegetables and frozen potatoes, we did not assess the frequency of consumption for individual product types, limiting the ability to describe consumption frequency within these categories of frozen foods. Finally, while our overall sample size was more than 1,700 respondents, small sample sizes for subpopulations and missing data limited the ability to make comparisons across some subgroups.

While our study demonstrated that consumers may amplify the risk of illness from certain frozen vegetable products through preparation practices, we did not assess why consumers are not following cooking instructions for frozen vegetables or why these practices may differ across demographics. This may reflect a lack of understanding that frozen vegetables need to be cooked, a preference for certain preparation methods, or the perception that frozen foods are less risky than other foods. In our study, respondents who ranked frozen foods as least risky/likely to be contaminated with germs were more likely to consume frozen vegetables raw than those who ranked them as more risky. Future studies focused on understanding why consumers may engage in suboptimal preparation practices can inform consumer education. Additionally, this study describes how consumer preparation practices vary across frozen vegetable types, which can inform frozen food risk assessments. In addition to Listeria, frozen vegetables may be contaminated with other pathogens, such as Salmonella (Denich et al., 2025; Kääriäinen et al., 2022). Given that consumers are preparing frozen vegetables in ways that may amplify the risk of illness caused by Listeria and other pathogens, preventive controls during the production of frozen vegetables are critical steps for reducing or eliminating the risk of illness among consumers.

Conclusions

This study characterized frozen vegetable and frozen potato consumption among Minnesota adults. Overall, self-reported compliance with always following cooking instructions was suboptimal and varied by product type. While frozen vegetables and frozen potatoes are considered NRTE products, these findings suggest that some consumers may be treating frozen vegetables as an RTE product, potentially increasing their risk of foodborne illness if the products are contaminated. These findings are useful for identifying which frozen foods might be higher risk given consumer preparation practices, such as leafy greens and carrots. By contrast, frozen potatoes were rarely consumed without cooking. Consumer behaviors should be considered in the development of risk assessments for frozen vegetables and frozen potatoes and for evaluating regulations for frozen food safety and informing prevention strategies.

Appendix A. Supplementary material

Supplementary material to this article can be found online at https://doi.org/10.1016/j.jfp.2026.100834.