In Judaism, Chadash (Hebrew: חָדָשׁ, ḥāḏāsh, "new [grain]") is a concept within Kashrut (the Jewish dietary regulations), based on the Biblical requirement not to eat any grain of the new year (or products made from it) prior to the annual Omer offering on the 16th day of Nisan.^[1]

Grain products which are no longer affected by this law are referred to as Yashan (Hebrew: יָשָׁן, yāshān, "old [grain]").

In Rabbinic Judaism, this requirement is restricted to the five species of grain – wheat, barley, spelt, rye and a fifth shibolet shual (which has been identified with oat, a species of barley called segala in Latin, and a kind of millet called sophonion in Greek). Any of these grains (or products made from them) that are too "young" to pass the requirement are referred to in Judaism as chadash "new [grain]". Additionally, the rabbinic interpretation requires grain to have taken root prior to the Omer offering for it to become permitted; therefore, grains planted after Passover could only be consumed, at the earliest, twelve months later.

Following the destruction of the Temple in Jerusalem, the Omer offering is no longer offered. Instead, the new grain becomes permissible following the date on which the offering was brought in ancient times. Chazal enacted a one-day further delay because of the extra day of holiday outside the Land of Israel.

The applicability of the Chadash rules to grain grown outside the Land of Israel is a subject of debate among halakhic authorities. Although the Mishnah and Babylonian Talmud record a Tannaitic dispute about applicability outside Israel^[2] the majority of medieval Jewish scholars (e.g. Moses Maimonides, the Rif, and the Rosh) forbade its consumption. The later codifiers of Jewish law for Ashkenazic and Sephardic Jewry followed suit, both Rabbi Moses Isserles and Rabbi Joseph Caro declaring the stringent position.

Nevertheless, the same Rabbi Isserles (at least for Ashkenazim) also ruled that, because in general, in cases of purchased grain (with no other information) there is a double doubt as to

• whether the grain was harvested before Passover of that year (which would render it yashan) and
• whether, even if harvested after Passover of that year, it took root before Passover of that year (which would at least put its status in doubt)

the combination of doubts renders general grain permitted.^[3]

In addition a novel lenient approach was presented by Rabbi Yoel Sirkis who felt it is permissible if the grain originally belonged to a non-Jew.^[4] Additionally, the manner in which various foods have historically been available has meant that Jewish populations would need to risk starvation to pursue stringent compliance with this aspect of kashrut. All these factors led to a situation in which observation of the Yashan regulation was relatively limited until very recently (at least in the Ashkenazic community).

In modern times, particularly in developed countries, food is much more readily available than it historically had been, and grain is in sufficient abundance that many Orthodox Jews have become more interested in observing chadash restrictions. Modern packaging practices, which in some nations involve the stamping of production dates on every package, often allow individuals to determine whether food is definitely yashan (not "chadash"); packaging organisations sometimes add Kashrut information to the packaging, and sometimes include in this information whether the product is known to be yashan.

• Joseph Herman, A Guide To Chodosh