I would like to find books published about cuisines of Saudi Arabia; cookbooks, spices, culinary heritige of the country. What would be the best way to search?
The Library is currently reviewing subject headings for cookbooks, but they have not yet been updated - so the best way to search the catalog at the present moment is to use the term "cookery" along with Saudi Arabia. Of course, you can also search for cuisine, spices, foods, and so on using the keyword option.
The following titles are from the Library of Congress catalog:
Salah, Nahda S.
Main Title: Arab world cook book : the book of one thousand and one delights / cooking and text by Nahda S. Salah ; photography by Basem S. Salah.
Dhahran, Saudi Arabia : Said Salah International Publications Agencies, 1973, 1977 printing. 345 p.
LC Classification: TX725.N36 S24
Main Title: Helen Corey’s food from biblical lands : a culinary trip to the land of Bible history.
Terre Haute, Ind. (146 S.E. 23rd St., Terre Haute 47803) : H. Corey, c1989. 154 p.
Notes: "Foods of Syria and Lebanon ... Jordan, Palestine, Egypt, Morocco, and Saudi Arabia."
LC Classification: TX725.M628 C67 1989
Ashkhain's Saudi cooking of today / Skipwith, Ashkhain.
London : Stacey International ; Atlantic Highlands, N.J. : Distributed in the U.S.A. and Canada by Humanities Press,
1986 160 p.
ISBN: 0905743423; 9780905743424 LCCN: 86-202650
Descriptor: Cookery, Saudi Arabian.
Identifier: Food: Arab dishes - Recipes
Saudi Arabia, Printed by al-Mutawa Press 
Related Names: Lucas, Eva Maria, [from old catalog] ed.
Ras Tanura Women’s Group. [from old catalog]
171 p. illus. (part col.) maps. 22 cm.
LC Classification: TX715 .R334
Long, David E. Culture and customs of Saudi Arabia / David E. Long. Saudi Arabia
Westport, Conn. : Greenwood Press, 2005. 124 p.
Contents: Introduction: land, people, and history -- Traditional Islamic culture and modernization -- The extended family roles -- Cuisine and dress -- Social customs, rites of passage, and holidays -- Communication and mass media -- Artistic expression.
LC Classification: GN635.S28 L66 2005
The following are not found in the Library of Congress, but do appear to contain material on Saudi Arabian cooking. They are from WorldCat:
The best of Near Eastern cookery :
favorite dishes from the Balkans, Turkey, Israel, Jordan, Saudi Arabia & other countries of the Arabian Peninsula /
Ann Seranne; Eileen Gaden
1964 1st ed. 158 p.
Garden City, N.Y. : Doubleday,
Title: The Middle Eastern cookbook /
Khalifé, Maria. Masciocchi, Corinne.
West, Stuart. Northampton, MA : Interlink Books, 2007
Standard No: ISBN: 1566566754; 9781566566759
Abstract: Over 120 traditional recipes from the Middle East, including: Bahrain, Egypt, Iran, Iraq, Jordan, Kuwait, Lebanon, Saudi Arabia, Syria, the United Arab Emirates, and Yemen.
Cooking of the Gulf :Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates / Mallos, Tess.
Publication: London : Parkway, 2004 64 p.
ISBN: 1898259062 (pbk.); 9781898259060 (pbk.); National Cookery -- Persian Gulf States.
From a book review in Library Journal, 2008:
"While there are numerous books on Middle Eastern cooking, few of them focus on the food of the Gulf States: Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. Al-Hamad, a food writer who lives in London and Kuwait, provides a brief introduction to the cuisine and culture of the area, followed by favorite traditional recipes. She describes the food as "largely a combination of Indian, Persian, and Turkish cuisine," because the ancient spice route traversed the region, and dishes such as Chicken Biryani, from Persia, and Red Lentil Stew, an Indian dal, reflect these ancient influences. All of the recipes are shown in color photographs, and there are photos of street life and striking landscapes as well. For most subject collections."
al-Hamad, Sarah. Cardamom and Lime: Recipes from the Arabian Gulf. Interlink: Interlink Pub. Group. Nov. 2008. c.128p. photogs. index. ISBN 978-1-56656-725-1. $26.95. COOKERY
All of the above were found limiting my searches to Saudi Arabia - you could very likely find much more by searching for cuisine/food/cooking of Persian Gulf states or Arab/Arabian Gulf, or even Middle East, but you would need to then inspect the books individually for Saudi Arabian material.
The Arab table :recipes and culinary traditions /
Bsisu, May. New York : William Morrow,
2005 369 p.,  p. of plates : col. ill. ; 26 cm.
ISBN: 0060586141; 9780060586140 LCCN: 2005-46045
Descriptor: Cookery, Arab.
Note(s): Includes index.
Class Descriptors: LC: TX725.A7
From the lands of figs and olives :
over 300 delicious and unusual recipes from the Middle East and North Africa /Author(s): Salloum, Habeeb. Peters, James.
New York : Interlink Books,
Year: 1995 253 p. : col. ill. ; 27 cm.
ISBN: 1566561590; 9781566561594; National Library: 980012953
Descriptor: Cookery, Arab.
Cookery, Middle Eastern.
Cookery, North African.
Note(s): Includes indexes.
Class Descriptors: LC: TX725.A7;
Spice :flavors of the Eastern Mediterranean /
Sortun, Ana, 1967- Chaison, Nicole.
Publication: New York : ReganBooks 2006
381 p.,  p. of plates : ill. (some col.) ; 24 cm.
ISBN: 0060792280 (alk. paper); 9780060792282 (alk. paper) LCCN: 2005-55186
Descriptor: Cookery (Spices)
LC: TX819.A1; Dewey: 641.6/383
A few websites that might be of some interest:
Bedouin profile, from Joshua project
Saudi Arabia Travel Guide (food)
Food from Saudi Arabia, in Saudi Aramco World, 1975
Additional Ways to Contact Us
Send written correspondence to:
African and Middle Eastern Division
Library of Congress
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Washington, D.C. 20540-4820