Acorn Use for Food, Harvesting and Nutrition

Guest Post by David A. Bainbridge 

ACORN HARVESTING

            Harvesting acorns should be very similar to the harvesting of other commercial nuts such as almonds or filberts. Wolf (1945) found that it was possible to collect from 110-660 kg (50-300 lbs) of acorns per hour with very simple hand tools. My own experience has confirmed these numbers. However, when harvesting small acorns, like Q. gambelii, in an off year it may be possible to collect only a few pounds per hour.

ACORN NUTRITION

            The nutritional qualities of 18 species of acorns are described in Table 1. California's acorns are described in Table 2.

TABLE 1.  ACORN COMPOSITION, 18 SPECIES

                                                 Percent          

Water                                          8.7 - 44.6

Protein                                         2.3 - 8.6

Fat                                               1.1 - 31.3

Carbohydrate*                          32.7 - 89.7

Tannin                                         0.1 - 8.8

KCAL/100 gms                         265 - 577

KCAL/lb                                  1200 - 2600

* or N free extract

(Bainbridge, 1985a).

TABLE 2. CALIFORNIA ACORNS

Species              Water        Protein               Fat      Carbohydrate    Tannin

Q.agrifolia1         9.0              6.26                 16.75         54.57            --

Q.chrysolepis¹    9.0              4.13                 8.65           63.52            --

Q.douglasii¹       9.0              5.48                 8.09           65.50               --

Q. douglasii²     40.75            3.03                 4.77           43.39            3.61

Q. dumosa²       44.58           2.29                 3.42           40.65           5.15

Q. kellogii¹          9.0              4.56                17.97        55.48            --

Q. kellogii²        37.6              3.43                11.05        32.71            1.81

Q. garryanna¹      9.0              3.94                 4.47           68.87            --

Q. lobata¹            9.0              4.90                 5.54           69.02            --

Q. lobata²          40.57            2.82                 4.25           43.44            3.85

Q. wislizneii²     29.80            3.08                 14.47         40.40            4.60

Lithocarpus

   densiflora³      36.00            2.06                 8.50           38.29            --

Indian corn⁴      12.5              9.2                   1.9             74.4              --

Wheat⁴              11.5              11.40               1.00           75.4              --

¹Wolf (1945), ²Wagnon(1945), ³Heizer and Elsasser (1980), ⁴Wagnon (1946)

            X-ray diffraction showed that the structure of acorn starch from Q. mongolica and Q. crispula fell between that of corn and potatoes. Acorn starch had limited gelatinization at 61-68oC, with gelatinization of Q. crispula lowest and Q. mongolica highest (Kim and Lee, 1976). The amylose content of acorn starch was 27.1 percent, blue value 0.43 and Aldehyde number 1103 (Chung et al., 1975). Acorns are also good sources of some vitamins, with 5 - 54.8 mg of Vitamin C per 100 gm of raw acorn (Djordjevic, 1954; Minieri, 1954). This compares favorably with the Negev lemon, with 58.1 mg per 100 g. Acorns are also an excellent source of Vitamin A, with 180 IU per gm in Q. phellos (King and Titus, 1943). Twenty-seven grams, or less than tenth of pound of acorns, would meet the suggested daily requirement of 5,000 IU for vitamin A. This may prove of great benefit in areas of the world where vitamin A deficiency is common among the poor. Thorough testing of a full range of oak species and oak processing methods may well discover other species with even higher levels of these and other vitamins and trace elements.

            Acorns include many essential amino acids, Table 3. (Luk'yanets, 1978; Videl and Varela, 1969). Testing is needed to establish the amino acid content of the California species. Minor deficiencies can probably be rectified with complementary legumes, fish, or meats. When acorns are cooked with ash, to neutralize bitterness, the acorn foods should also be a good source of calcium. Cooking with ash may also make more niacin available if the tests Ruttle (1976), conducted on corn are replicable for acorns. Acorns also supply many trace elements. It is not at all surprising that acorn-based cultures prospered for thousands of years with this excellent food base.

TABLE 3: AMINO ACID CONTENT OF ACORNS

                                    milligrams/gram

Glycine                        0.98 - 1.37

Alanine                        1.02 - 1.57

Valine                          0.97 - 1.22

Leucine                       1.69 - 2.08

Isoleucine                    0.63 - 0.72

Serine                          0.94 - 1.23

Threonine                    0.87 - 1.13

Methionine                  0.26 - 0.31

Phenylalanine              0.90 - 1.09

Tyrosine                      0.68 - 0.99

Lysine                         1.19 - 1.51

Arginine                      1.48 - 2.25

Histidine                     0.71 - 1.05

Proline                        1.41 - 1.58

Aspartic acid               2.75 - 3.66

Glutamic acid              3.10 - 4.33

(Luk'yanets, 1978).

Acorn Use as Food, Introduction

Guest Post by David A. Bainbridge 

Presented at the Symposium on Multiple-use Management of California's Hardwoods, November 12-14, 1986, San Luis Obispo, California

Abstract:

Acorns are a neglected food for people, livestock, domestic fowl, and wildlife in California. Acorns are easy to collect, store, and process. In addition to the nutritious nut and meal, acorns yield an oil comparable in quality and flavor with olive oil. The existing acorn market could be greatly expanded and provide new income for rural people. A serious effort to identify and propagate the best oak acorn cultivars for these products is long overdue. It is particularly appropriate for this research to be done in California, which once had an acorn based economy.

INTRODUCTION

            Acorns have been used as food by Homo sapiens for thousands of years virtually everywhere oaks are found. The worldwide destruction of the acorn resource by mismanagement may well have led to the development of annual plant based agriculture and to civilization as we know it today (Bohrer, 1972; Bainbridge, 1985b). In Europe, Asia, North Africa, the Mid-East, and North America, acorns were once a staple food, (Hedrick, 1919; Loudon, 1844; Brandis, 1972; Lefvebre, 1900; and Bishop, 1891). The Ch'i Min Yao Shu, a Chinese agricultural text from the sixth century recommends Quercus mongolica as a nut tree (Shen Han, 1982). In Spain and Italy acorns provided 20 percent of the diet of many people just before the turn of the Century (Memmo, 1894).

            Acorns were perhaps nowhere more important than in California. For many of the native Californians acorns made up half of the diet (Heizer and Elsasser, 1980) and the annual harvest probably exceeded the current California sweet corn harvest, of 60,000 tons. Acorn foods remain on the market not only in Korea, China, and North Africa, but in most major American cities, at Korean food stores (Wolfert, 1973; Bainbridge, 1985a).

            A reevaluation of acorns and their uses is long overdue. The acorns of all 500 species should be tested. Although the acorns of some oaks are probably too small or too hard to open for widespread use many species that can and should be planted for use as food. They are also valuable feed for domestic animals and birds, and wildlife.

            The factors that made acorns a major food source in California in the past make them attractive candidates for greater use in the future. They often ripen all at once and are easy to collect. They store well and were kept by the native Californians for several years in simple storage bins (Merriam, 1918). They are simple to prepare, even for the varieties that need to be leached. Although most species are bland, as are corn and wheat; some have good flavor and could be used in place of other nuts.

            The yield of acorns per acre compares well with grains. When the long-lived, deep-rooted oaks can reach sufficient water; acorn production can be very high, with yields of more than 5,280 kg/ha (6,000 pounds/ acre) (Bainbridge, 1986). High acorn yields can be maintained on hilly lands where annual grain crops cause severe soil erosion (Bainbridge, 1987a).

Non-Profits, Pay Attention to your Customers

This post is motivated by an article that appeared in the Harvard Business Review about 30 years ago.  To the best of my memory, the author was Andersen.  HBR reprints are behind a pay-for firewall, so I am going by memory.

One of the difficulties of non-profits is that we lack the feedback provided by customers freely making decisions based on costs and prices.  Consequently, it is easy to slip into some thought traps.  Here are a few of those traps:

Joe Isuzu

Picture the stereotypical, used car salesman; resplendent sparkling polyester and mismatched plaids that make your eyes bleed.

He is in the selling thought trap.  The product he has on his lot is the BEST PRODUCT EVER.  End of story.

You might think you need a two year old minivan.  But if he does not have one on the lot, he will honestly believe that you need to buy his 4 year old Toyota RAV4.

His is a circular logic.  I have the best vehicles on my lot.  The reason these cars are on my lot is because they are the best cars.

It is good to have pride in your products/services...but not at the expense of listening to the customer.

Monte Motorhead

Monte is a car fanatic.  He devours car magazines.  He can quote statistics until your eyes glaze.  You want to buy a two year old, Chrysler minivan.  He wants to sell you a Turbo Porsche Carrarra.  You want utility.  He cannot understand why you do not orgasm over the sublime perfection of the TPC.

He is trapped in the product focus thought trap.

Martha Monolith

Martha actually makes marketing surveys.  She pours over the data and tries to figure out who her target is.

She has trouble focusing because the data seems to dance all around from survey to survey.  Still she tries.  If she is running the used car lot she buys a bunch of minivans at auction one month.  The next month it is pickup trucks.  Then it seems like she buys all sporty sedans.  She gets frustrated because the customers cannot seem to make up their mind.

She is in the simple market thought trap.

Patty Patchwork-Quilt

Patty also makes marketing surveys.  But her operating assumption is that "the market" is segmented like the sections of an orange.  We go through similar stages as we progress through our lives.  We are never identical, but we are likely to share certain needs as we pass through common stages.

She has some economical vehicles for those just starting out.

She has a portfolio of "family" vehicles to match varying family sizes and budgets.

She has some recreation type vehicles for families in their peak earning years.

She also has some more upscale, economical vehicles for those who might be in their empty nest years but want some luxuries and a higher level of dependability (and cost) than those just starting out.

She has some of this and some of that and the lot is arranged by cluster.

Non-Profits

The "market" for non-profits is segmented.

Some people who are growing oak and chestnut trees focus on high production, high quality orchard trees.

Other people are passionate about landscaping for wildlife.

Others are passionate about reclaiming devastated landscapes like strip-mines, highway right-of-ways and eroded farm fields.

Some are motivated by the concept of integrating urban landscaping with the potential for cities to produce more food.  They see it as a way of addressing the issue of urban food deserts.

Others are geeked about the legacy of planting trees that might outlive them by 300 years.

Each constituency (and I am sure I am missing some) has slightly different priorities and this blog will attempt to serve them all.

Squirrel Caches

Well, I limbered up my Google-fu to investigate squirrel caches.

Red Squirrels are the species most likely to fill "cavities" with nuts.

Proximity to the nest was listed as a variable.

"Salting" the cavity with a few nuts was suggested.

Here is a web page discussing a Squirrel Cache Condo.  The house this guy built is a beautify piece of craftsmanship.  It looks like a whole lot of work.  I am more of a plywood, PVC pipe and 5 gallon bucket kind of guy.

Other webpages indicated that a healthy population of Red Squirrels is closely correlated to mature, cone bearing trees.

So far, I have seen little info about ground squirrels cache activities.  I can attest that they do it.  I have some running shoes (New Balance, size 11), a partial roll of baling twine and a truck air cleaner that were filled up with corn by those little rascals.

Squirrels Revisited

Control

A fellow blogger posted an excellent technique for trapping tree-rats.

"I've been told a single fox squirrel can cause 200 pounds of pecan losses in a single year. With that amount of crop loss, "old bushy tail" may be the most serious pest of pecans."

Some people claim rat traps work well for red squirrels.

Partnership

I recall stumbling across obscure articles in the past where the author wrote about building or supplying boxes of specific dimensions.  These boxes were irresistible storage locations to squirrels...they crammed them full of nuts.  I recall hearing of mandolins, shoe boxes and intake manifolds on engines that squirrels filled with hickory nuts.  Just guessing, but key variables might be

• The size of the opening (it certainly is for bird boxes!)
• The dimensions of the box
• The location (height above ground) of the box
• The orientation of the opening

 It is good to have dreams.  One of my dreams is that instead of eradicating squirrels, they become my unpaid field workers.  The only time I would help a squirrel slip his mortal coil would be when I wanted to eat one.

More Work

I recall sitting in Fitzgerald Park in Grand Ledge, Michigan after a hike and watching the squirrels carry acorns (Q. alba) 150 feet to bury them in the sand of a volleyball court.  One could have collected them by shoveling through a sieve of hardware cloth...but that is a lot of work.

Cecil Ferris, a notable breeder of filberts, would sometimes supply eager visitors (me) with seedlings that volunteered out of his compost pile.  There never seemed bot be a shortage of seedlings popping up.  They were planted by the squirrels.

Cecil used a .177 pellet gun to control the squirrels.  It was a rare year when he killed fewer than 100 of the beasts.

Wildlife Travel Corridors

According to Mike Parker, a wildlife biologist, something magical happens when a wildlife corridor is more than 60 feet (20 meters) wide.

Large animals feel more secure traveling along them, especially as the corridor matures and develops more vertical structure.  That is, dense, brushy edges with taller trees and more openness through the center.

Smaller animals have greater nesting success in the wider corridors as well.  A predator can harvest a narrow corridor as efficiently as you can select a package of bacon at Krogers.  The predator has no trouble finding the nest because it only has to search in one dimension.  The +60' wide corridor with vertical structure is baffling to predators.  A raccoon or possum might smell a bird nest, but dang, it is a lot of work to find it.

So, how can chestnuts and oaks be integrated into a wildlife corridor?

It is convenient to divide oaks and chestnuts into two categories.  Lets call them "orchard types" and "timber types".  A cross-section through a wildlife corridor might look like the graphic below.  S=Shrub, O=Orchard type tree, T=Timber type tree.  The number represent the number of feet between rows within the corridor.  Distance between rows is very flexible and depends, in part, on climate and soil moisture issues.

5'-S-5'-O-10'-T-20'-T-10'-O-5'-S-5'    Note that this creates a "mounded" appearance in cross-section.

I can only speak for Eaton Rapids, Michigan.  Shrubs are sometimes omitted.  Sometimes they are autumn olive, brambles, filberts, pawpaws or dogwood.

• Orchard trees I have used include Chinese Chestnuts (C. mollisima) and Sawtooth Oak (Q. acutissima).  I have also seen some Gambel Oak (Q. gambelli)  that would work great in this application. Other, non oak/chestnut trees include apple, pear, American plum, persimmon and mulberry.
• Timber trees include Sawtooth Oak (Q. acutissima), Burr Oak(Q. macrocarpa), Swamp White Oak(Q. bicolor), English Oak(Q. robar), Hybrid Chestnuts (with American or European somewhere in their ancestry).  I also sprinkle in Black Locust (Robinia psuedoacacia) for nitrogen fixing capability and to provide "sacrifice" trees to open up canopy as the trees size up.

Note to readers:

Writing can be very intimidating.  One of my goals is to "lower the bar" for writing...a bit like watching Uncle Billy water ski.  Watching somebody else flail away, and seeing that they are having a good time while flailing will make it easier (I hope) for others to contribute.