Natural Resources, 2011, 2, 240-243
doi:10.4236/nr.2011.24030 Published Online December 2011 (
Copyright © 2011 SciRes. NR
Biblical Milk Taboos and Scientific Methodology
with Ancient Nomenclature
David Iluz1,2,3, Zohar Amar4, Michael Goldberg5,6, Uzi Merin7, Yitzhak Katz5,6
1The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel; 2Talpiot College, Holon, Israel;
3Beit Berl College, Kfar Saba, Israel; 4Department of Land of Israel Studies and Archaeology, Bar-Ilan University, Ramat-Gan, Israel;
5The Allergy and Immunology Institute, Assaf-Harofeh Medical Center, Zrifin, Israel; 6Department of Pediatrics, Sackler Faculty of
Medicine, Tel Aviv University, Israel; 7Department of Food Science, Agricultural Research Organization, Volcani Center, Bet Dagan,
Received August 23rd, 2011; revised October 3rd, 2011; accepted October 10th, 2011.
Human society and its religions and cultures have laid out numerous guidelines, often involving dietary restrictions
(Deut. 14:4-5; Lev. 11:2-7). One such set of restrictions still observed by many Jews today relates to the distinction be-
tween pure and impure, edible and forbidden mammals (Talmud Bavli, Avoda Zara 35b). The ancient Jewish dietary
laws (kashrut) have often perplexed both gentiles and Jews, since they appear to be arbitrary. Here we demonstrate that
the separation of pure and impure animals coincides with taxonomic, biochemical, allergenic, and common nutritional
Keywords: Milk, Allergy, Mammals , Kosher
1. Introduction
The Biblical passages addressing mammalian kashrut
appear in the book of Deut.: “These are the beasts which
we may eat: the ox, the sheep, and the goat, the Ayyãl,
and the Zěbi and the Yahmr, and the Aqq, and the
Dišn, and the Těổ, and the zemer” (Deut 14:4 - 5). See
also (Lev. 11:2 - 7). There are disagreements on some
animal’s names (see Amar et al. [1]). As one notes from
reading the above, the passages listing the rules provide
examples of animals to illustrate their application, but
does not give any justification.
An additional characteristic distinction between kosher
and nonkosher animals was provided by the Talmud (T.
Bavli, Avoda Zara 35b), a collection of Rabbinic notes
about the Jewish oral tradition thought completed around
the 5th Century AD, as well as the treatise “The Medicine
Book of Asaph Harofe” (8th - 9th Century AD). Both cite
the ability to curdle milk as an additional sign distingui-
shing between these two groups [2]. According to this
criterion, it is only the milk of pure animals that curdles
while the milk of impure animals does not. The curdling
test was accepted by the medieval philosopher, physician,
and theologist, Moses Maimonides (referred to by others
as the Rambam) (1138-1204) in his treatise “Mishneh
Torah” (The Law in Review) (Maimonides Laws of For-
bidden Foods , 3, 12) and in subsequent religious texts.
2. Methods
To examine the validity and generality of this criterion,
the milk of various mammals was tested by two techni-
ques. The first test was carried out immediately after
milking using the enzyme rennin, which is the standard
method. The second technique utilized an Optigraph
(Ysebaert, Frepillon, France), which is an instrument that
measures the clotting time of milk and the degree of
firmness of the curd (Figure 1).
Speed tests were carried out on making the coagula-
tion using the Optigraph. 10 ml of sample of milk en-
tered to well on the device, temperature of 30 degree
determind. as soon as it reached a temperature set, have
been added 0.5 ml of coagulation enzyme solution—Fro-
mase 15 TL (Gist-Brocades nv, Delft, The Netherlands)
for coagulation speed of 600 seconds. the degree of firm-
ness of the curd is determined by the intensity of trans-
mission intensity light (in volts).
Description of the Optigraph Device Operations
The optigraph measures the intensity of the Near Infra
Red light beam in through one centimeter of the milk
sample, located in quartz glass. Reading in volts, treated
Biblical Milk Taboos and Scientific Methodology with Ancient Nomenclature241
Curd firmness (volt)
Time (min)
Figure 1. Example of results of curdling dairy cow (con-
tinuous line) as opposed to horse (dashed line ) as spee d tests,
coagulation and strength are obtained using the optigraph
as mathematical power for drawing a shape like cham-
pagne glass. A straight line from the bottom of the curve
to the start of opening walls of the Cup is the time that
passes through the point of clotting (beginning of cheese
making) as soon as milk start making a cheese, the cur-
ves are opened due to strongest of cheese. The walls of
the Cup describes the strength of cheese and Creates a
drawing of a typical champagne Cup, with arbitrary
values of volts, called every few seconds and a continu-
ous curve.
Patients with a clinical history consistent with IgE-
mediated CMP allergy and a positive skin-prick test (SPT)
were evaluated for cross-sensitization to milk-derived
proteins from both kosher and non-kosher species. On
the other hand, in experimentation, milks were tested for
their ability to curdle after the addition of rennin, and
clotting time and degree of firmness were quantitated by
the Optigraph method.
3. Results
The results of the analyses showed the formation of cur-
dling in the milk of the cow (Bos taurus), sheep (Ovis
aries), goat (Capra aegagrus hircus), buffalo (Bubalus
bubalis), fallow deer (Dama d. dama), red deer (Cervus
elaphus), ibex (Capra ibex), and the reticulated giraffe
(Giraffa camelopardalis reticulate)—all defined as rit-
ually pure animals. In contrast, no curdling was observed
in the milk of the mammals which the Torah defines as
ritually impure: the horse (Equus caballus), donkey (Eq-
uus asinus), camel (Camelus dromedaries), alpaca (La-
ma pacos), pig (Sus scrofa domestica), rabbit (Orycto-
lagus cuniculus), monkey (Macaca fascicularis), and
dog (Canis familiaris ). Human milk was also included in
this category (Figure 2).
Figure 2. Results of testing clotting of different dairy mammals as they are graphically; shows two arms that create a kind of
anti-shaped cup, those are pure animals while a straight line or narrow shows impure animals. The values on the vertical axis
shows the time in seconds until the beginning of clotting.
Copyright © 2011 SciRes. NR
Biblical Milk Taboos and Scientific Methodology with Ancient Nomenclature
Another common denominator shared by the milks of
the various kosher-animal species is their allergenic
potential. The impetus to study the allergenic potential of
kosher-versus nonkosher-derived milk was based on an
intriguing article demonstrating that the evolutionary
relationships of kosher-animal milk casein genes were
more closely related to each other than to nonkosher
species (Figure 3) [3] (casein is one of the more highly
allergenic proteins in milk).
This was followed by a study aimed at determining
whether a patient allergic to the IgE in cow’s milk showed
differences in cross reactivity to kosher versus non-kosher
animals [4]. All the patients who were allergic to cow’s
milk protein (CMP) tested positive by the skin-prick test
(SPT) for cross-reactivity to goat, ibex, and giraffe (n =
27, p = 0). In contrast, reactivity to milk from the non-
kosher animal species was significantly lower: only one
out of 22 patients (4.5%) cross-reacted to milk of horse,
6/27 (20.83%) to pig, 7/27 (25.9%) to dog, 5/27 to alpaca
(18.5%), 5/27 to camel (18.5%), and 3/27 (11.1%) to
rabbit. Eight controls did not react to any of the milk
species tested (Figure 4). Indeed, camel milk has been
suggested as a protein source for nutrition for children
allergic to cow milk [5].
We, thus, began to try to find out whether there were
any unique sequences that would explain why milk-
protein allergy could be divided into responses to kosher
and nonkosher. We noted that a unique stretch of eight
amino acids is common to the κ-casein of the milk from
all kosher (pure) animals [6]. This sequence is not pre-
sent in the κ-casein of any of the non-pure animals. It is
noteworthy that while no detailed mechanism has been
published for the curdling of milk in general [7], it is ge-
nerally accepted that the firmness of the curd requires the
Figure 3. Taxonomic relationships of pure versus impure
mammals (after Gatesy et al. 1996 [3]). The pure mammals
are marked.
Figure 4. Allergenic responses of patients sensitized to cow’s
milk to milk of pure and impure mammals.
formation of casein multimers, which would be facili-
tated by the cysteine present in this eight-amino-acid
One has to marvel at the fact that the Biblical dis-
tinction between kosher and nonkosher can be re-estab-
lished based on modern methods and parameters totally
unknown in antiquity.
4. Acknowledgements
The authors thank Prof. Zvy Dubinsky of Bar-Ilan Uni-
versity, Israel, for advice and comments. We thank
Sharon Victor for the English editing
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Copyright © 2011 SciRes. NR