Olive pomace – kedushat shevi'it in olive oil production

The olive oil preparation process generates much waste, most of which is known as olive pomace and olive mill wastewater (OMWW). Do these two byproducts have kedushat shevi'it? Plus: on uses for olive oil waste in past and present.

Rabbi Moshe Bloom, Cheshvan 5783

In Israel, olive orchards span 320,000 dunam (nearly 80,000 acres) from the Galilee to the Negev. Of them, 250,000 employ dryland farming methods while the remaining 70,000 dunam are irrigated regularly. The orchards grow approximately 80,000 tons of olives and produce some 15,000 L of olive oil and another 20,000 tons of table olives (Israel Olive Council 2021, from Zalul, an environmental NGO).

In the olive oil production process, after oil extraction, two main byproducts remain: olive pomace (also known as olive waste) and olive mill wastewater (OMWW; mei eker). Pomace is a solid residue containing skin, pulp, fragments of olives, olive kernels, and some oil remnants.

One ton (1000 kg) of olives produces approximately 200 L of olive oil (20%). The rest of it (80%) is pomace and OMWW. That is, in Israel, this comes out to roughly 60,000 kg each year.

According to most posekim, olive pomace and OMWW do not have kedushat shevi'it.

Mishnah (Shabbat 3:1) notes that olive pomace (gefet) is flammable and was used to fuel the stove:

If a stove was lit … with pomace (gefet), and with wood, [one may] not place [a pot atop it on Shabbat] until he sweeps [the coals from the stove while it is still day] or until he places ashes [on the coals, so that the fire will not ignite on Shabbat.]

In his gloss on the Mishnah, Rambam explains that pomace (which can refer also to the pulp of any other fruit or seed when liquid is extracted from them) specifically refers to olive waste: "And pomace, the olive waste left after oil is squeezed from them."

Tosefta (Shevi'it 5:19) states that olive pomace of the seventh year may be used as fuel.

Rambam rules accordingly (Shevi'it 5:19): "We may not use hay and straw of the Sabbatical year for kindling. We may, however, use the wastes of olives and grapes of the Sabbatical year for fuel."

It is forbidden to use edible materials with kedushat shevi'it as fuel. Because olive pomace, as opposed to hay and straw, is not edible for animals on its own nor is it intended as fodder (or human food), it does not have kedushah. Thus it is permissible to use it as fuel.

Even though pomace sometimes contains residual oil, because no one attempts to extract it, the pomace does not have kedushah (see below). Likewise, theoretically, pomace can be used as part of a fodder mix because pomace cannot be eaten on its own but only as part of a mixture, and also because this use is not at all common, it does not have kedushah.

Note that the Mikdash David (Rabbi David Kohen Rappaport, 1890–1942) wrote that olive pomace has kedushat shevi'it, but nevertheless it is permitted to use as fuel since it has no other use. According to this approach, the pomace needs to be handled as having kedushat shevi'it. However, the halachah does not follow his opinion.

Mishpatei Eretz (published by the Beit Midrash for Halachah in Agricultural Settlements – Emunat Ish) states that if the olives are not adequately squeezed and still contain olive oil, the pomace has kedushat shevi'it. From a conversation with Rabbi Yosef Efrati, this refers to rare cases when the olives were not squeezed properly, not to the two-phase method (see below), which likely extracts more olive oil from the olives than was possible in Mishnaic times.  

The ruling of Torah VeHa'aretz Institute is that pomace does not have kedushat shevi'it since no one actually extracts the remaining oil, and only in rare cases one feeds it to animals and even then it is mixed with other additional substances before given to the animals.

Uses of olive pomace in the past

Fertilizer – Ancient Roman writings mention olive pomace used to fertilize fields.

Fuel and light – We saw in the Tosefta that pomace was used for fuel. It was necessary to dry the moist pomace in the sun. After it was dry it could be used as fuel.

Soap – During the Middle Ages in the Land of Israel, the oil remaining in the pomace (2-7%) was used to prepare soap.

Use of pomace today

Today pomace is not viewed as a resource, but rather a nuisance—waste that olive presses do not know how to deal with.

Waste removal – in most cases, pomace is disposed of in olive orchards, other orchards, fields, and open areas.

Fuel and kindling – Pomace is used as fuel for energy production and sold as briquettes and pellets for fuel in wooden stoves, fireplaces, or heaters for the garden in the private sector. The pomace is mixed and processed, compressed and dried, and turned into rolls.

Energy production – Energy production at special energy plants. This is already done in Sprain; in Israel, there is a company working on this as well.

Soap and cosmetics—Especially in small farms (see p. 64).

Fertilizer and compost – See, for example, the Meshek Tzippori farm.

Fuel – Currently studies are being conducted on the uses of pomace to produce ethanol as motor fuel.

Animal fodder – Currently studies are being conducted on using olive pomace as fodder for ruminant mammals (especially bovines). Here, the pomace is mixed with additional substances for animal feed. Note that olive pomace includes substances that may interfere with the digestive system of the animals. One recent study indicated that the product is marked by low digestibility and suitable only for non-milk-producing cows (calves, cows not yet producing milk).
See Dr. Akiva London, Use of waste (שימוש העקר), Alon Noteah 67, 2013.

Olive pomace oil – In certain countries (currently not Israel), oil remnants are extracted from the pomace through a refining process with the use of chemicals (such as hexane) and by heating the pulp mixture to an extremely high temperature. Exposure of the natural fats in the oil to extremely high heat may produce polycyclic aromatic hydrocarbons (PAHs) like benzopyrene, which research has shown to be carcinogenic (note that this is more likely for countries without regulation on PAHs). In any event, olive pomace oil is considered the lowest-grade oil and therefore is considerably less expensive than its virgin olive oil counterparts. (See Daniel Williams, "Olive pomace oil: not what you might think," The Olive Oil Times, 9 Sept., 2010). 

Types of pomace

After cleaning and washing, pressing, and mixing the olives, comes the olive extraction process. There are two methods used for oil production at oil presses: two-phase and three-phase.

In the two-phase method, the olive paste is transferred to a centrifuge that extracts the oil from the paste. The pomace and wastewater come out together on one side while the oil comes out on the other side.

In the three-phase process, in the first centrifuge, the pomace is removed from the liquids, while in the second centrifuge the water is removed from the oil. The OMWW is acidic.

In the two-phase process, the remaining pomace is moist and contains oil remnants (2-7%) that are not exploited, while in the three-phase process the pomace is relatively dry.

Olive mill wastewater

Olive mill wastewater is composed of olive washing water (approximately 5% of the weight of the olives, olive pulp water (40-50% of the initial olive weight), water added to olive paste during centrifugation, and water from washing extraction plants (5-10% of the weight of processed olives). Olive mill wastewater has an adverse effect on the environment due to its highly polluting organic load. However, it does contain phenolic compounds which are rich in antioxidant properties. Therefore, these bioactive compounds have been recognized as a potential target for food, cosmetic, and pharmaceutical industries. While attempts are being made to recover these phenolic compounds and exploit them, this has not become a standard yet (Membrane Technologies for Biorefining, 2016, p. 163). For this reason, it is clear why this water does not have kedushat shevi'it, at least at this point.
 

Expanded sources

Mishnah (Shabbat 3:1) notes that olive pomace (gefet) is flammable and was used to fuel the stove:

In his gloss on the Mishnah, Rambam explains that pomace (which can refer also to the pulp of any other fruit or seed when liquid is extracted from them) specifically refers to olive waste:

Furthermore, the Mishnah in Shabbat (4:1) on the prohibition of insulation (hatmanah) on Shabbat, states:

Here, in his gloss, the Rambam extends the definition of pomace to include sesame seed pulp:

Tosefta (Shevi'it 5:19) states:

Rambam rules accordingly (Shevi'it 5:19):

It is forbidden to use materials with kedushat shevi'it as fuel. Because olive pomace, as opposed to hay and straw, is not edible for animals nor is it intended as fodder (or human food), it does not have kedushah and thus it is permissible to use it as fuel.

Even though moist pomace (see below) contains residual oil, because no one attempts to extract it, the pomace does not have kedushah. Likewise, while at times olive pomace can be used to prepare a fodder mix, because it cannot be eaten on its own but only as part of a mixture and also because this use is not at all common, it does not have kedushat shev'I't.

Mishpatei Eretz (22:12, n. 20) states that at olive oil mills the byproducts do not have kedushat shevi'it. However, if the olives are not squeezed thoroughly and there are oil remnants in the pomace, the pomace would have kedushat shevi'it. He adds that if one generally feeds pomace to livestock, in that case, too, the pomace would have kedushat shevi'it.

Mikdash David (59:4, s.v. katav haRambam, p. 438; Rabbi David HaKohen Rappaport, 1890-1942) innovates that olive pomace does have kedushat shevi'it but nevertheless it is permissible to use it for fuel since it cannot be used otherwise. It seems that Mishpatei Eretz (ibid.,) rejects the stringency of the Mikdash David:

Mikdash David:

The Yerushalmi (Shabbat 3:1) compares olive pomace to slow-burning wood. Thus there is a concern that one would come to stoke the coals, as opposed to straw, which burns rapidly, for which this concern does not apply.

Katif Shevi'it (5781) 19:39:

Rabbi Yehuda Amichay writes as follows:

Expansion on animal manure

The Gemara deliberates about the status of manure and concludes that the droppings of sheep and goats (beheimah dakah, lit. small livestock) are similar to olive pomace, which burns slowly, while manure of large livestock (beheimah gasah) are comparable to straw that burns rapidly. Alternatively, it is possible that the intent of "small" and "large" refer to the manure itself. See Korban Ha'eidah. Some maintain that the opposite is true: the manure of small livestock is comparable to straw while that of large livestock is like olive pomace; see Pnei Moshe.

The Yerushalmi (Shabbat 3:1) discusses if manure can be compared to straw and hay on Shabbat which are consumed rapidly, so there is no concern that one would stoke the fire. Or, if manure is similar to olive pomace and wood, which burns slowly, in which case there is a concern that one would come to stoke the fire:

Yerushalmi Shabbat 3:1:

Korban Ha'eidah, Shabbat 3:1

Penei Moshe Shabbat 3:1