Pág. 1
PRESERVING TRADITION AND PROMOTING
INNOVATION: “QUESILLO,” ARTISANAL
CHEESE FROM OAXACA, MEXICO
PRESERVAR LA TRADICIÓN Y PROMOVER LA INNOVACIÓN:
“QUESILLO”, QUESO ARTESANAL DE OAXACA, MÉXICO
Danae Alicia Martínez Martínez
Instituto Tecnológico de Oaxaca, México
Alma Dolores Pérez Santiago
Instituto Tecnológico de Oaxaca, México
Marco Antonio Sánchez Medina
Instituto Tecnológico de Oaxaca, México
Iván Antonio García Montalvo
Instituto Tecnológico de Oaxaca, México
Diana Matías Pérez
Instituto Tecnológico de Oaxaca, México
Carlos Francisco Varapizuela-Sánchez
Instituto Tecnológico de Oaxaca, México
Emilio Hernández Bautista
Instituto Tecnológico de Oaxaca, Méxic
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DOI: https://doi.org/10.37811/cl_rcm.v8i5.13504
Preserving Tradition and Promoting Innovation: “Quesillo,” Artisanal
Cheese from Oaxaca, Mexico
Danae Alicia Martínez Martínez
1
dnamtz31@gmail.com
https://orcid.org/0009-0005-2483-1620
Instituto Tecnológico de Oaxaca
México
Diana Matías Pérez
dian_1007@hotmail.com
https://orcid.org/0000-0002-6592-9342
Instituto Tecnológico de Oaxaca
México
Alma Dolores Pérez Santiago
alma.ps@itoaxaca.edu.mx
https://orcid.org/0000-0002-4410-7307
Instituto Tecnológico de Oaxaca
México
Carlos Francisco Varapizuela Sánchez
varapizuela_7@hotmail.com
https://orcid.org/0000-0002-3803-8886
Instituto Tecnológico de Oaxaca
México
Marco Antonio Sánchez Medina
marco.s.medina@itoaxaca.edu.mxm
https://orcid.org/0000-0002-1411-5955
Instituto Tecnológico de Oaxaca
México
Emilio Hernández Bautista
emilio.hb@itoaxaca.edu.mx
https://orcid.org/0000-0001-8893-7647
Instituto Tecnológico de Oaxaca
México
Iván Antonio García Montalvo
ivan.garcia@itoaxaca.edu.mx
https://orcid.org/0000-0003-4993-9249
Instituto Tecnológico de Oaxaca
México
ABSTRACT
The quesillo is a traditional food originally produced in the state of Oaxaca, Mexico, is fresh, spun paste
or strands, made with raw milk and has unique sensory attributes due to its extensive native microbiota,
mainly lactic acid bacteria, which are fermenting microorganisms, safe, are used in the fermentation
and preservation of food helping to improve flavor, aroma, and texture. They are part of the natural
microbiota of raw milk and its derivatives, mainly traditional cheeses, where the greatest diversity and
heterogeneity is found. The objective of this study was to microbiologically identify lactic acid bacteria
(LABs) present in the traditional quesillo of Oaxaca, Mexico. Quesillo samples were collected in three
municipalities in Oaxaca, Mexico. Serial dilutions were prepared from 10 g of sample, then seeded in
a Man, Rogosa, and Sharpe (MRS) selective medium. Subsequently, they were incubated at 30 °C for
24 to 48 h. The strains were identified macroscopically and microscopically, catalase and oxidase tests
were performed as confirmation tests for LAB. From the three traditional quesillo samples, 86 colonies
with BAL macroscopic morphology were identified, strains with yeast morphology, coccobacillary,
catalase and oxidase positive were discarded, and finally 56 strains were identified with macroscopic
and microscopic characteristics of LAB type, gram positive, bacillary and coccobacillary morphology,
catalase and oxidase negative. In conclusion, quesillo is a traditional product that presents lactic acid
bacteria as important microorganisms, which, in addition to improving sensory attributes and food
preservation, can present probiotic properties that when administered in adequate amounts confer a
health benefit to the host.
Keywords: quesillo, lactic acid bacteria, traditional food, probiotic
1
Autor principal
Correspondencia: dnamtz31@gmail.com
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Preservar la Tradición y Promover la Innovación: “Quesillo”, Queso
Artesanal de Oaxaca, México
RESUMEN
El quesillo es un alimento tradicional producido originalmente en el estado de Oaxaca, México, es
fresco, de pasta hilada o en hebras, elaborado con leche cruda y posee atributos sensoriales únicos
debido a su extensa microbiota nativa, principalmente bacterias lácticas, que son microorganismos
fermentadores, inocuos, se utilizan en la fermentación y conservación de los alimentos ayudando a
mejorar su sabor, aroma y textura. Forman parte de la microbiota natural de la leche cruda y sus
derivados, principalmente quesos tradicionales, donde se encuentra la mayor diversidad y
heterogeneidad. El objetivo de este estudio fue identificar microbiológicamente las bacterias lácticas
(BAL) presentes en el quesillo tradicional de Oaxaca, México. Se recolectaron muestras de quesillo en
tres municipios de Oaxaca, México. Se prepararon diluciones seriadas a partir de 10 g de muestra y se
sembraron en un medio selectivo de Man, Rogosa y Sharpe (MRS). Posteriormente, se incubaron a 30
°C durante 24 a 48 h. Las cepas se identificaron macroscópica y microscópicamente, se realizaron
pruebas de catalasa y oxidasa como pruebas de confirmación de BAL. De las tres muestras de quesillo
tradicional se identificaron 86 colonias con morfología macroscópica BAL, se descartaron cepas con
morfología levaduriforme, coccobacilares, catalasa así como oxidasa positivas, y finalmente se
identificaron 56 cepas con características macroscópicas y microscópicas de tipo BAL, grampositivas,
morfología bacilar y coccobacilares, catalasa y oxidasa negativas. En conclusión, el quesillo es un
producto tradicional que presenta bacterias lácticas como microorganismos importantes, que además de
mejorar los atributos sensoriales y la conservación de los alimentos, pueden presentar propiedades
probióticas que administradas en cantidades adecuadas confieren un beneficio a la salud del hospedero.
Palabras clave: quesillo, bacterias ácido lácticas, alimento tradicional, probióticos.
Artículo recibido 06 agosto 2024
Aceptado para publicación: 10septiembre 2024
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INTRODUCTION
Quesillo or string cheese is an artisanal product originally produced in Oaxaca, Mexico (Villegas, 2016)
is an integral part of the culture, traditions, and gastronomy of the region, so its denomination acquires
a heritage dimension (Cervantes et al., 2019), is very popular, and in other states of the country it is
called Oaxaca cheese (Villanueva-Carvajal et al., 2012). Traditional cheeses in Mexico are
characterized mainly by being made with raw bovine milk, the process is done by hand by members of
the family (Patiño-Delgado et al., 2022), on a small scale in workshops or roof houses set up inside the
home (Camacho-Vera et al., 2019), also incorporate traditional ingredients that give the product its own
identity (Villegas de Gante et al., 2013); quesillo is a fresh type of cheese, spun paste or strands, with
great melting capacity; its production requires skill and knowledge; during its manufacture the paste or
curd undergoes a natural fermentation that causes its acidification, so that when it is kneaded with hot
water it plasticizes and can be stretched to form strips or fibrous threads (Caro et al., 2013), thus
acquiring the unique sensory attributes (flavor, aroma and texture) conferred by its diverse native
microbiota, among which lactic acid bacteria are the most important. Lactic acid bacteria (LAB) are
safe, nonpathogenic, fermenting microorganisms (FAO, 2006), produce lactic acid as the main product
when fermenting carbohydrates (Mokoena, 2017); are unicellular, nonmotile, nonspore-forming, Gram-
positive, anaerobic, catalase and oxidase negative organisms of bacillary or coccoid morphology
(Miranda et al., 2021). These microorganisms are used mainly in the food industry in fermented food
preservation processes due to the production of bacteriocins, hydrogen peroxide, and diacilli, which
prevent the proliferation of pathogenic microorganisms (Arena et al., 2018); are used as starter cultures
to promote the development of flavor, aroma, improve texture, and increase the shelf life of fermented
products (Wang et al., 2021).
LAB can be found in fermented products of vegetable and meat origin (Ashaolu and Reale, 2020),
however, these microorganisms appear to be predominant because they play a fundamental role in lactic
fermentation during the traditional cheesemaking process and exhibit a complex microbiota with greater
diversity and heterogeneity (Mathur et al., 2020), these bacteria play an essential role in the processes
of fermentation, maturation and flavor development (Coelho et al., 2022), also make it possible to
maintain or even improve the nutritional value of the raw material (Caro et al., 2013), there are several
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strains of LAB such as Lactococcus, Lactobacillus, Streptococcus, Leuconostoc, Enterococcus,
Weissella and Pediococcus (Terzić-Vidojević et al., 2020). However, there are also several strains of
LAB that are used in cheese production, such as Lactococcus, Streptococcus, Lactobacillus and
Leuconostoc, as they produce lactic acid, which acidifies the medium and contributes to the
characteristic flavor and texture of the cheese. These bacteria may be added to the cheese directly or
may be naturally present in the environment or in the milk used to make the cheese. LAB have been
proposed as a novel approach due to their ability to confer health benefits as they are recognized as
probiotics, mainly the genus Lactobacillus (Reuben et al., 2020), due to the transformation of substrates
and the formation of bioactive or bioavailable end products, with the capacity to aid in digestive health
(Kim et al., 2019). Generally used as dietary supplements, they are also considered an important group
of functional foods (Soemarie et al., 2021). Therefore, the objective of this study was to isolate and
microbiologically identify the LAB present in quesillo traditionally made in Oaxaca, Mexico.
METHODOLOGY
Sample collection
Samples of quesillo made from raw bovine milk were collected from municipalities belonging to the
Valle Eteco region, Oaxaca, located northwest of the Central Valleys, at coordinates 17° 12'27'N
96°48'00'W (see Figure 1). Samples were collected under hygienic conditions and transported at
refrigerated temperature (4 to 7 ºC).
Figure 1. Location of the district of Etla, in the state of Oaxaca.
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Isolation and purification of strains
Samples were coded with Q1, Q2, Q3 then homogenized to prepare serial dilutions from 0.1 to
0.0000001, then 100 µl of each dilution was placed in solid Man, Rogosa and Sharpe (MRS) medium,
using the surface spreading technique, then incubated at 30 °C under anaerobic conditions for 24 to 48
h. Differentiated colonies were selected, then successive reseeding was performed by the cross streaking
method, subsequently incubated at 30 °C for 24 to 48 h.
Macroscopic and microscopic identification
Colonies were identified with characteristics of white or cream color, round or dotted shape, creamy or
moist appearance, diameter of 1 to 2 mm, convex surface and entire edges. For the identification of
microscopic morphology, Gram staining was performed and later, they were observed under a 100x
optical microscope. Colonies identified as gram positive and bacillary, coccobacillary and coccoaceous
morphology were selected. Catalase and oxidase tests were performed as confirmatory tests.
Strain conservation
Strains of lactic acid bacteria with gram-positive, catalase-negative and oxidase-negative bacillary,
coccobacillary and coccal morphology were preserved in MRS broth with 30% glycerol and stored at -
20 °C in cryopreservation vials.
RESULTS AND DISCUSSION
From three samples of quesillo made with raw bovine milk, 86 colonies were identified with
macroscopic morphology of lactic acid bacteria, which presented characteristics of white or cream
color, diameter of 1 to 2 mm, round shape, punctiform, entire edges, convex or flat surface, butyrous
and moist consistency. All isolates were identified as gram-positive, presenting blue-purple coloration
in microscopic identification at 100x, and were also characterized by catalase and oxidase test.
According to the results obtained, 65 isolates were identified as negative catalase, since they did not
react when 3% H
2
O
2
was added, while 21 isolates were positive for gas production; in the oxidase test,
65 isolates were identified as negative oxidase since they did not react when the Kovacs reagent was
added (Table 1). In the microscopic morphology identification, of the 65 LAB isolates, 12 were rods,
while 44 were coccobacilli and 9 were cocci. Finally, 56 Gram positive strains were selected,
morphologically bacilli and coccobacilli, with negative catalase and oxidase (Table 2).
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Table 1. Strains with macroscopic and microscopic characteristics presumptive for lactic acid bacteria,
growth at 30 °C for 24 h in MRS culture medium.
Microscopic morphology
Isolated
strains
Macroscopic
characteristics
Gram
Bacillary
Cocácea
Cocobacillary
Catalase
(+)
(+)
86
White or cream
color, diameter
1-2 mm, round
shape, pointed,
entire edges,
convex or flat
surface, buttery
and moist
consistency.
86
13
29
44
21
Table 2. Microscopic morphology of catalase-negative lactic acid bacteria.
Sample
Q1
Q2
Q3
Total
Catalase (-)
18
26
21
65
Bacillus
0
6
6
12
Cocobacillus
16
16
12
44
Cocos
2
4
3
9
The quesillo or Oaxaca cheese is a dairy food that during its elaboration process the paste or curd goes
through a fermentation process under the action of lactic acid bacteria present in raw milk, traditionally
this process lasts from 18 to 24 hours, which confers unique and distinctive sensory attributes of this
product, mainly the characteristic of texture in long strands or threads, with great melting capacity. In
addition to its nutritional contribution, mainly protein and fat, this traditional cheese may have some
functional properties due to the lactic acid bacteria it contains, such as probiotic properties. Roldán-
Pérez et al. (2023) points out that artisanal cheeses could provide new native strains with probiotic
properties to develop innovative dairy products with positive effects on human health. Rolim et al.
(2020) indicates that cheese is considered a better carrier of probiotics compared to many dairy
products, due to its lower water activity (aw > 0.90), low storage temperature (4-8 °C), relatively higher
pH compared to traditional dairy products, and textural characteristics such as high fat content, which
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protects probiotics during gastrointestinal transit.
Lactic acid bacteria (LAB) isolated from traditional quesillo from Valle Eteco, Oaxaca, made with raw
milk, show that these microorganisms are part of the natural microbiota of cheeses; Miranda et al. (2021)
points out that LAB can be found in various types of traditional cheeses, which favors the development
of sensory attributes characteristic of these cheeses. Coelho et al. (2022) indicates that the presence of
lactic acid bacteria predominates in raw milk cheeses produced in an artisanal way, mainly the genera
Lactococcus spp, Leuconostoc spp, Lactobacillus spp and Streptococcus spp. The macroscopic and
microscopic characteristics presented by the lactic acid bacteria strains isolated from the three quesillo
samples, such as size 1-2 mm, white or creamy color, round shape, punctiform, entire edges, convex or
flat surface, buttery, dry and moist consistency, correspond to typical characteristics of lactic acid
bacteria previously reported by Santander-Cortés & Castro-Rosas (2024); as well as the microscopic
characteristics of Gram-positive bacteria, morphology of cocci, bacilli and coccobacilli, catalase and
oxidase negative, coincides with that reported by Goa et al. (2022).
CONCLUSIONS
In conclusion, we can say that quesillo or Oaxaca cheese belongs to the fresh type classification, with
spun paste or strands, with great melting capacity, made with raw bovine milk, it has unique sensory
attributes due to its wide native microbiota, mainly lactic acid bacteria. Lactic acid bacteria (LAB) are
safe microorganisms, widely used in the food industry, mainly in the production of fermented dairy
foods; the various by-products derived from the fermentation of these microorganisms, confer
antimicrobial properties, conservation and improvement of sensory attributes (flavor, aroma, texture,
color), which allows improving the quality and safety of food. From the tests carried out on the quesillo,
56 strains of lactic acid bacteria were isolated that showed macroscopic and microscopic characteristics
typical of these bacteria, which indicates that this traditional cheese from Valle Eteco, Oaxaca, could be
a promising source for the isolation of lactic acid bacteria that can present probiotic properties and later
its application in the elaboration of functional foods.
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