Italian squash: zucchini graded by size for a consistent prep line

Italian squash is the trade name for dark green zucchini, the straight, glossy summer squash that Los Angeles restaurants order every week. King Quality Produce grades it by size so prep comes out the same every day: Fancy, Extra Fancy, Medium and #2, packed in 22 lb boxes and available year-round from growers in Mexico, the American Southwest and California. Here is what buyers should know.

What it is and how the sizes work

Zucchini is a soft-rind summer squash, Cucurbita pepo, eaten whole and immature. The UC Davis Postharvest Technology Center puts flowering to harvest at 45 to 60 days and notes that growers pick very immature fruit, before the seeds enlarge and harden; a thin, soft rind and glossy skin are the signs of that immaturity². Quality rests on uniform shape, tender rind, firmness, glossy color and a well-trimmed stem, with no yellowing on dark green types².

The trade grades zucchini by inches. The University of California's summer squash production guide lists the California convention for U.S. No. 1 zucchini as Extra Fancy at 5 to 6 inches long and 1 to 1.5 inches wide, Fancy at 6 to 7 inches long and 1.25 to 1.75 inches wide, and Medium at 7 to 8 inches long and 1.75 to 2.25 inches wide³. Western markets generally want 5 to 6 inch fruit while eastern markets accept 7 to 8 inches³. KQP uses the same three names plus #2, which is sound, firm fruit that runs past Medium or shows cosmetic marks, priced for dicing, grating and soups.

Where it grows and when

The UC guide puts maturity at about 60 days from planting and notes that growers harvest every other day for months³. In California the major areas are the Imperial Valley, the Central Valley from Kern to Merced counties, and the south-central coast from Santa Barbara north, with main production in spring and summer and acreage dropping in fall because of virus and whitefly pressure³. A UC Cooperative Extension cost study for the southern San Joaquin Valley describes the program: transplant in March, harvest from mid-May to mid-July, with a second planting in August⁶.

Mexico fills the rest of the calendar. A University of Florida analysis found that Mexico supplied 96 percent of U.S. fresh squash imports in 2020, that imports rose from 386 million pounds in 2000 to 1,089 million pounds in 2020 while U.S. fresh squash production fell 43 percent, and that more than 90 percent of the Mexican volume arrives between October and June⁵. The UC guide, published in 1999, noted that Los Angeles terminal prices were highest in mid-March, after Mexican shipments declined, and high again from October through December³. For KQP that means Mexican and Southwest fruit through the cool months and California fruit from late spring into fall.

How to buy: USDA grades and what to check on receiving

The USDA standard for summer squash, effective September 2016, has two grades and no size requirement⁴. U.S. No. 1 must be fairly young and fairly tender, fairly well formed, firm, with stems attached, and free from decay and damage; U.S. No. 2 must be firm and not old and tough, free from serious damage⁴. Fairly young and fairly tender means tender skin, tender undeveloped seeds and firm, moist seed-cavity tissue, and firm means the fruit does not yield to slight pressure and is not wilted⁴. Size may be specified by diameter or length in inches and quarter inches, which is exactly what the Extra Fancy, Fancy and Medium convention does⁴.

On receiving, look for glossy skin and a cleanly cut stem. UC Davis says fruit should be cut from the vine rather than snapped and that a poorly trimmed stem end promotes decay². Press gently for firmness, reject pitting or water-soaked spots, which are chilling injury, and check for scuffing and compression on the soft rind². The UC guide notes that zucchini is commonly packed in 28 lb cartons; KQP packs 22 lb, a lighter box that turns faster³.

• Pack: 22 lb box
• Grades: Fancy, Extra Fancy, Medium, #2
• Availability: year-round, Mexico, the Southwest and California

Storage and shelf life

UC Davis recommends 41 to 50 F (5 to 10 C) at 95 percent relative humidity, with a storage life ideally no more than 10 days². Zucchini is the most chilling-tolerant of the summer squashes and has kept acceptable market quality for up to two weeks at 41 F, but shriveling, yellowing and decay climb beyond that². Below 41 F, chilling injury appears after a day or two as water-soaked pitting, discoloration and accelerated decay, and the damage is cumulative². Dehydration is the other common loss: fruit shrivels quickly unless it is cooled promptly².

Zucchini breathes hard when warm. UC Davis measured respiration at 42 to 48 milliliters of CO2 per kilogram per hour at 68 F against 7 to 10 at 41 F, so time on a warm dock is costly². Ethylene sensitivity is low to moderate, but low levels speed yellowing in green types, so keep it away from the ripening room². Hold the box at 45 F, do not stack heavy cases on it, and turn it inside a week.

Nutrition

USDA's FoodData Central entry for zucchini with skin, raw, lists 17 calories per 100 grams, with 94.79 grams of water, 3.11 grams of carbohydrate, 1 gram of fiber, 2.5 grams of sugars and 1.21 grams of protein¹. Minerals include 261 mg of potassium, 18 mg of magnesium, 16 mg of calcium and 8 mg of sodium; vitamins include 17.9 mg of vitamin C, 24 micrograms of folate, 0.163 mg of vitamin B6, 120 micrograms of beta-carotene, 2,125 micrograms of lutein plus zeaxanthin and 4.3 micrograms of vitamin K¹.

Two numbers stand out. The 17.9 mg of vitamin C is about 20 percent of the 90 mg Daily Value; the National Institutes of Health describes vitamin C as an antioxidant required for collagen synthesis that plays a role in immune function and improves absorption of nonheme iron from plant foods^{1, 7}. NIH also notes that prolonged storage and cooking reduce vitamin C⁷. The 261 mg of potassium is a step toward the adequate intake NIH sets at 3,400 mg a day for men and 2,600 mg for women, against a 4,700 mg Daily Value; NIH says potassium supports nerve transmission, muscle contraction and fluid balance, and that Americans generally consume less than recommended^{1, 8}.

In the kitchen

Zucchini crosses every cuisine in Los Angeles. Italian kitchens fry it for zucchini fritti and shave it raw with lemon and parmesan. Mediterranean and Middle Eastern restaurants grill planks, stuff it for kousa mahshi and fold it into Persian kuku kadoo. Mexican kitchens use dark zucchini alongside grey squash in calabacitas. Markets sell it loose by the pound.

Match the grade to the cut. Extra Fancy for grilling, roasting whole or halved, stuffing and anything plated where shape shows. Fancy for the everyday saute and the salad bar. Medium for coins and planks where yield per pound matters. #2 for dicing, grating, pureeing into soups and anything where the squash disappears into the dish. The UC guide also notes that male zucchini flowers are harvested and sold, so ask us when your menu calls for blossoms³.

Call the KQP office at (213) 627-7181 or email office@kingqualityproduce.com for this week's Italian squash counts, grades and pricing.