Southern province.

Several participants were able to trace their origins to different parts of Africa. Most Tonga participants in Southern Province believed that they were the first settlers in the area, with most being unable to trace their origins beyond the borders of Southern Province (S1 Table). This was also true for some sections in the Ila ethnic group that mentioned that they landed from God onto the land where they settled:

Briefly explain to me about where your ethnic group/ tribe came from and how they came to settle down in this area

“… .there are many stories. The word Namwala came from a big flat stone on the tributaries of the Kafue river where you find a lot of footprints of human beings, animals, and snakes, they are there even now. The Ila people say that is where they landed when they came from God which is untrue. Those stones were curved by pigmies…there are so many stories. We are likely to have come from East Africa in the Sudanic region. Others were left in East Africa and others went to South Africa. They came round and this is why you find Tonga-speaking people in Malawi. We first landed in Kalomo according to written history… .” (Ila male, 60+ years old, Choma).

The love for their land and their connections to their ancestors at this stone, from which the town name Namwala originated from was evident. They related their way of life as cattle herders to this place of origin. The Ila people are known to have the largest herds of cattle in Zambia, making them very wealthy. However, as quoted above, more educated participants traced their origins to East Africa where cattle and milk production are high and the indigenous people have been known to produce different types of fermented milk [36].

Western province.

The Lozi participants from Western Province traced their origins to Congo where their queen Mbuyawamwambwa migrated from. Around 1860 when the Kololo from Lesotho attacked Barotseland where they lived, they were defeated and the Kololo ruled them for 22 years. Participants reported that the Kololo imposed their way of life and their language on the Lozi people. It is possible that the Kololo may have also imposed the practice of mabisi production and consumption as it has been reported that this practice is very similar to the people of South Africa where the Kololo migrated from [37, 38].

Eastern province.

Participants from Eastern Province traced their origins to different parts of Africa; mainly Mozambique (for participants from Sinda), Malawi, and/ or South Africa (for participants from Lundazi and Chipata) (S2 Table). Both groups of participants stated that their forefathers migrated as a result of wars they were fleeing from. The changing environment that ensued as a result of war ejected them into a different landscape where they had to adapt by adopting the way of life in the places where they settled, while at the same time losing parts of their language and identities with the acculturation that occurred. Others from Lundazi mentioned that their forefathers did not have enough farming land in Malawi which prompted them to migrate into Zambia in search of farming land. There, they acquired huge farming land on which they grew their crops. This may serve as an explanation for why these individuals continue to be recognized for their substantial maize production compared to other regions in Zambia.

Mabisi consumers.

Mabisi production and consumption were most prominent in Southern and Western Provinces, with a few consumers in Eastern Province. Consumers considered it as a normal regular food, consumed daily without any specific religious or traditional significance attached to it. They ascribed its importance to the fact that it was a readily available food and was a good source of energy and satiety. Mabisi was considered as food that should be readily available in every household as it was commonly offered to visitors as well, who would often times appear on people’s doorsteps without any reservation. It was therefore considered good practice to have some food available to offer their guests. This was more commonly practiced by participants from Southern Province. Mabisi was valued not only for its enjoyable taste but also for its health benefits by all consumers. In Western Province, it was believed that their common practice of consuming mabisi and other foods such as the head and brains of fish made them very intelligent.

Mabisi consumers reported that when consumed, it would keep them satisfied throughout the day, particularly when working in the field or when children went out to herd cattle. It was also given to children as a snack that was consumed at school or at home. Mabisi was consumed in many different ways which included consumption on its own as a drink or thick yogurt-like mixture, or mixed with other foods such as rice, sweet potatoes, pumpkin, or leftover nsima (a stiff porridge often cooked using maize meal flour, or sometimes from millet, sorghum, and/ or cassava flour). It is common knowledge that nsima is the Zambian staple food which is consumed with sides that include vegetables and a protein such as eggs, fish, meat or legumes. When these are unavailable, consumers mix the nsima with mabisi and this is consumed as a main meal. Almost all consumers mentioned that mabisi was often times used as a replacement for relish in times when they did not have any and therefore was a cheaper alternative:

" It is just taken like any other food, no special reasons for consuming it. It can take the place of relish in meals and it is even cheaper. (Tonga female, 60+ years old, Choma).

Origins, production and consumption of mabisi. When participants from Southern and Western Provinces were asked where the practice of mabisi production and consumption originated from, they either stated that it was a tradition passed down through generations and they were unsure of its exact origin, or they reported that it was a result of accidental circumstances:

Was mabisi part of the foods that they (your forefathers) ate? If yes, kindly explain how they first learnt of making and consuming mabisi?

"I think it happened that they milked and ate what they could each day and left what remained in the vessel. The following day they found it had become a heavy solidifying liquid. They started calling each other to see what had happened and then stirred it as everyone was watching. They tasted it and found that it was nice and they shared it amongst themselves. This is how they started fermenting the milk overnight. From then, excess milk was not wasted. It all started with excess milk that was left to ferment overnight." (Tonga female, 60+ years old, Choma).

"Some of these things were done as experiments. They did not even know they were doing something good, they just discovered that it came out well and it was nice to eat." (Lozi male, 60+ years old, Mongu)

Unfortunately, most of the younger participants were unable to locate the origins of mabisi:

Was mabisi part of the foods that they ate? If yes, kindly explain how they first learnt of making and consuming mabisi?

“Yes, but I do not know how it started. I just found it that way.” (Tonga male, 30+ years old, Choma)

Most participants reported that their forefathers used gourds and calabashes to ferment their milk into mabisi (Fig 1). The methods and source of milk used to produce mabisi are generally the same with only slight variations depending on taste preferences and identity (Fig 2). Some participants preferred a more stiff and sour product that was kept to ferment for a longer period of time, while others preferred a more watery product that resembled drinking yogurt. Many participants ascribed meaning to the type of mabisi that was traditionally prepared by their ethnic group as described by [27]. For instance, when asked whether they consumed mabisi produced from goat milk, it was dismissed as a practice that was not part of the Lozi ethnic group but that of the Tongas:

“No, unless the Tonga people who milk goats. Here we don’t.” (Lozi male, 40+ years old, Mongu)

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Fig 1. Calabash used to ferment mabisi.

https://doi.org/10.1371/journal.pone.0310507.g001

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Fig 2. General process flow of mabisi production [34].

Variations exist based on location [27].

https://doi.org/10.1371/journal.pone.0310507.g002

However, it was observed that goat milk was not common in any of the three subject areas and many participants responded negatively when they were asked whether they would consume it if made available. Nonetheless, a few respondents felt that goat milk was healthier than cow milk and mentioned that it produced more cream and therefore would make very good mabisi. This group of participants was willing to produce mabisi using goat milk if made available in large quantities.

The Ilas in Southern Province reported that elderly men were responsible for making mabisi, continuously shaking the calabash throughout the day until the mabisi was formed.

In contrast, the Tonga women were responsible for making mabisi. They allowed the fresh milk to stand in a calabash or gourd overnight for 24 hours (or more) when the mabisi would be ready for consumption. This showed differences in the foodscape between the two ethnic groups that are found in the same province. Those from Western Province reported that while they also used calabashes to ferment their milk, they formed a hole on the side bottom of the calabash which was used to drain the whey, after which they would add fresh milk and leave it to ferment again. This process was continued for three to seven days (depending on their taste preferences). The fermentation time depended on the container and the temperatures. Many participants reported that they had discontinued the use of calabashes and gourds because they did not grow them anymore and they were no longer readily available. They had resorted to using plastic or metal buckets and containers which they reported to be more convenient (Fig 3). They also mentioned that the plastic and metal containers were cleaner than the calabashes which they felt accumulated a lot of dirt and that the calabashes were not as durable as the plastic and metal buckets:

“I think it is because of the coming of modern technology with new equipment that can be used to ferment mabisi. Also, calabashes would break when they fell down. The cans we have do not break easily, they have a long lifespan.” (Tonga male, 19+ years old, Choma)

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Fig 3. Mabisi produced in plastic or metal buckets.

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They did, however, report that mabisi produced in calabashes was tastier and that they much preferred it over the one produced in plastic containers.

All participants were aware of mabisi and reported that it was consumed on its own or with other foods such as rice, nsima or pumpkin.

Mabisi non-consumers.

In an attempt to understand why most participants in Eastern Province did not consume mabisi, we asked them if they or their forefathers produced and consumed mabisi. Their responses were mixed. Several reported that they did not consume mabisi and that it was not part of their culture:

“No we never left any milk to stand overnight. In fact, this sour milk you’re talking about, I never heard of it until I was an adult….I have never had sour milk.” (Nsenga male, 50+ years old, Sinda).

“No because we do not see it. We have just heard that people from Southern province consume it but here in Eastern province we do not have it.” (Ngoni male, 60+ years old, Chipata).

However, it appears that despite not being popular, mabisi production and consumption was practiced by some of the Eastern Province ancestors. Participants mentioned that their forefathers did not move with cattle during migration but acquired them in the areas where they settled as an adoption and embrace of the new landscape. This changed their foodscape as they were now able to produce and consume milk, cow meat and possibly mabisi from the herds that they reared. Based on the main author’s understanding, interviewing the participants, and reading on the subject, it is possible that the practice of mabisi production may have been acquired from the people they interacted with during the migration process. Participants mentioned that mabisi consumption later discontinued mainly due to the loss of animals to diseases. This reverse change in the foodscape resulted in fewer animals that were available to produce enough milk for mabisi production, which consequently resulted in a gradual loss of interest and taste for mabisi over successive generations (S1 Fig). Other participants that had a preference for mabisi but did not have any source of milk felt that purchasing it was a waste of money and therefore chose not to consume it at all. Participants that mentioned that their forefathers consumed mabisi were mostly from poor backgrounds as was evidenced by an example given below:

Could you tell me a little about yourself, where you were born and your upbringing?

“…….we did not write on paper at the time we used to write on the floor….. we lived a hard life because my father did not have any job…..I went up to grade 7 but for me to go to form 1 my father did not have any money to take me. I therefore got married but that was when my life turned for the worse. I did not have a peaceful life but God blessed me with children……Right now I live with my husband and all we do is sell some bananas whenever they are ready for sale.” (Chewa female, 60+ years old, Lundazi)

In contrast, those that mentioned that their forefathers did not consume mabisi were from higher-income backgrounds. Leftover milk was thrown away in non-consuming households and considered to be rotten milk, while others stumbled on the product accidentally (as mentioned by those from Southern and Western Provinces below) and considered it a good product. The foodscape during this time was characterized by having excess milk that was discarded by some and used to produce mabisi by others. The main author of this paper derives her origins from the Eastern Province and did not grow up consuming mabisi. Despite the fact that she lived in a more cosmopolitan town with regular interactions with consumers, her family still did not adopt this practice. During this study, she informally asked her father and grandfather about why they did not consume it. Their answers were consistent; “We do not consume rotten milk, it is not part of our culture.” When she probed why not, her grandfather explained to her that when he was growing up, they would sell fresh milk to the Indians that lived near the village where he lived. This provided a ready source of income for other foods that they purchased.

Pride and identity also played an important role in mabisi consumption, with specific groups identifying themselves with a certain way of life and did not want to “corrupt” the norms and traditions they were identified by. Study participants from Eastern Province did not want to be associated with mabisi consumption, with most consumers reporting that the practice was only adopted when they interacted with the Tonga or Lozi ethnic groups from Southern and Western Provinces, respectively.

The food environment.

This section primarily focuses on the food environment as being part of the foodscape. Only those elements of the food environment that were reported by the participants as being important for their consumption of other healthy foods are reported here.

Food availability and accessibility. Participants described the importance of wild fruits and vegetables in the diets of their forefathers and in their upbringing. They consumed different types of bushmeat and wild vegetables and roots such as mupama and kabombwe. However, the foodscape changed over the years, with most of the bushmeat being unavailable to them as they mentioned that the animals may have been depleted, ran away due to urbanization, or stricter regulations had been placed by the government to conserve them. In response to the question about the availability of wild vegetables and roots, most participants reported that while they were still available to them, the foodscape had changed offering a wider variety of edible plants with the introduction of more cultivated vegetables, roots and tubers such as rape, cabbage, sweet potatoes and potatoes which were more desirable than the wild ones. They also mentioned that their children would not consume these foods as they were not familiar with them.

Participants further reported that with time, food availability in the villages had deteriorated as they were unable to find most of the foods that they consumed when they were younger. While participants acknowledged the changing food environment with a rise in the number of food outlets in their settlements, providing increased accessibility to processed items like cooking oil, these foods remained unavailable in their diets. This was attributed to the fact that they required money to purchase food, as opposed to the past when food was readily available in the wild without such financial demands:

“The type of food we used to eat a long time ago has changed because there was a lot of food then, but now there is even more food but requires that you have money.” (Chewa female, 50+ years old, Lundazi).

Farming methods and inputs also changed over the years. Crops such as rice, maize, and cassava were commonly grown in Mongu, while in Eastern Province, the commonly grown crops were millet, sorghum, maize, groundnuts, sweet potatoes, beans, and sunflower. In Southern Province, the commonly grown crops were maize, sweet potatoes, pumpkins, and millet. Despite these crops still being available, the introduction of new varieties that require fertilizers, herbicides, and other farm inputs to achieve a good yield affected their availability. Also, growing crops such as millet and sorghum was no longer desirable in some sectors as they were considered to be less profitable than growing other crops such as maize and rice:

“Ahh sorghum is better and not millet. If you have a certain portion of land, there are a lot of losses and you get very little from it as compared to sorghum and maize. But if you grow rice on the same portion of land, you get a lot more bags.” (Lozi male, 60+ years old, Mongu).

Food affordability. Farming activities form the central core and source of food in societies throughout the world. Several participants reported that they grew up in homes that reared cattle which served as a source of food or income for their households. As earlier mentioned, the entire subject population reported that their forefathers possessed large herds of cattle but these dwindled over time due to animal diseases and other factors. It is unknown where these animal diseases came from but it is clear that the changes in the landscape through these animal disease outbreaks negatively affected the health and well-being of these groups, adversely affecting their source of food and income. The significance of a healthy landscape has been emphasized by some indigenous communities by asserting, "if the land is sick, we are sick" [39]. The loss of animals was much higher in Eastern Province where it is possible that their cultural practices may have also contributed to their loss of cattle. Participants from Eastern Province reported that while they reared their cows for milk, they also slaughtered them for meat and shared it among their community members. In contrast, in Southern Province, it is unacceptable to kill cattle for meat. Instead, cattle herds have always been a symbol of wealth, and the cows were only slaughtered during festive periods, when they had bereavements, or when the cows were sick:

“Cattle were kept as a symbol of wealth. If you did not have a lot of cattle, it was a disgracing thing. We even had traditional dances and songs to show off cattle wealth.” (Ila male, 60+ years old, Choma).

In all three provinces, cattle were sold as a source of income to pay for their children’s school fees. Other commonly reared animals included goats (typically in Eastern Province and not Western Province), pigs (typically in Western Province), and chickens.

Other dietary practices.

The motivation to slaughter animals for consumption was largely driven by festivities and family events. Family taboos and traditions dictated that meat could only be consumed during Christmas or funerals. When a cow fell ill, the cow would also be slaughtered for consumption. Their diets were therefore mainly comprised of chicken meat or mice (in Eastern Province), when available, rather than cow meat. Monitor lizards (hopani) and tortoise meat were considered delicacies in Western Province and were consumed only by men. In response to the questions asked why they were only consumed by men, it was reported that it was just because it was rare meat that was kept only for the man of the house to enjoy. The men cut the monitor lizard into pieces and boiled it for approximately six hours when it would be ready for consumption:

“So yeah hopani is one of those, it’s a delicacy…….. and it is only prepared by men…..and you don’t cook it inside the yard. You cook it behind the yard not inside…. after some good 6 hours of cooking that’s when you remove the skins and the bones then you fry the meat. Very tasty like mincemeat, share it. You know the way we live in Western province we have the home set covered by some reed fence so that when you cook in your house nobody will know whatever you are cooking. But now since hopani is exposed outside you are forced to give other people…” (Lozi male, 60+ years old, Choma)

More commonly consumed foods throughout our subject population included groundnuts (and groundnut powder mixed with other relishes), wild fruits, vegetables, and roots; and cereals such as maize, millet, and sorghum. Some aspects of the local foodscape have remained the same as is evidenced by the consumption of these foods which have been in these communities through generations.

Besides mabisi, other fermented foods that were specific to different populations were produced and consumed. Chibwantu is a cereal-based beverage made from maize grits, with munkoyo roots added to speed up fermentation (Fig 4). This was typically reported by participants from Southern Province. The munkoyo roots are also used to produce munkoyo, while tobwa which was specific only to the Eastern Province, was reported as a commonly consumed beverage (Fig 4). While beer was also often mentioned as a common fermented beverage besides mabisi, some participants from Eastern Province mentioned chimela, muteteka and mphale. Chimela was used to produce tobwa which is a variant of munkoyo. Dried maize was soaked in water for three days and then slightly dried in the sun. It was then allowed to sprout in a sack that was placed inside the house, after which the sprouted maize was again dried in the sun before milling. Regularly dried maize was then mixed with the sprouted maize and milled together to produce chimela. Participants in Eastern Province also mentioned another fermented food called muteteka which was produced from maize grits. The grits were soaked for three to four days after which they were dried, milled using a mortar and pestle, and sieved to remove the bigger particles. The milled grits were then used to make porridge using the fermenting water and this product was called muteteka. They also made porridge using normally milled maize and fermenting water (from maize grits) to produce a porridge called mphale (Fig 5). While these foods were common during their childhood, most participants reported that they were no longer commonly produced as they now had hammermills where they could take their maize for milling rather than before when they had to use a mortar and pestle. A change in the foodscape that introduced more efficient ways of producing food resulted in a reduction in the consumption of these foods. Nonetheless, participants reported that when these foods were made available, they would consume them as a means to recollect their childhood memories and establish a connection between their children and their ancestral histories. Others mentioned that they still produced these fermented porridges as their traditional backgrounds strongly influenced their taste preferences.

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Fig 4. Different fermented maize beverages reported by the participants [40].

https://doi.org/10.1371/journal.pone.0310507.g004

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Fig 5. Fermented products described by participants in Eastern Province.

https://doi.org/10.1371/journal.pone.0310507.g005

Barriers to the consumption of healthy foods.

Consumption of healthy diets can be influenced by beliefs, norms and practices. While we explored the foodscape of mabisi in the different subject areas, we also wanted to determine the drivers of consumption of other healthy foods and the dietary practices that acted as contributors or barriers to their consumption. When asked whether there were any foods that were not permitted in their homes during their upbringing, several participants listed foods such as fish, eggs, mice, caterpillars, and kidneys. Most participants in all three provinces reported that as children, they were not allowed to consume eggs. It was believed that consuming eggs, particularly for girls, would negatively affect their fertility and their ability to bear children, while others were told that they would lose their hair. Pregnant women were also not allowed to consume eggs as it was believed that they would give birth to children without hair, while others believed that the egg would close off the birth canal and make childbirth difficult. It was also believed in the Eastern Province that children who consumed eggs would become epileptic or they would develop ringworms. In some sectors, eggs were used for traditional purposes by witchdoctors.

Fish was also discouraged for children as it was believed to affect fertility. Other foods such as goat meat, caterpillars, and certain types of mice in Eastern Province were also forbidden for children as they were believed to cause hair loss, ringworms and rash, and infertility in girls. While these practices were followed during their upbringing, participants reported that these beliefs were no longer practiced and they believed that their parents and forefathers followed this lifestyle as a way to ration food in the house, always ensuring that the head of the household (father) had enough food to eat.