Food Science for Gardeners: Grow, Harvest, and Prepare Nutrient Dense Foods

by Robert Pavlis

Everyone's guide to using the power of science to produce healthier and tastier fruits and vegetables.

From garden to fork, Food Science for Gardeners is everyone's guide to optimizing the quality of garden produce and preparing the most delicious and nutritious food possible.

Beginning with a high-level overview of food quality and nutrient density, this invaluable resource then takes a deep, but accessible, dive

The essential nutrient groups—proteins, carbohydrates, fats, vitamins, minerals, and fiber—as well as phytonutrients and their antioxidant properties Factors affecting food safety such as pesticides, microplastics, bacteria, and other forms of chemical and biological contamination The pros and cons of a host of approaches to storage and preservation including canning, drying, pickling, and fermentation An extensive variety of cooking methods and how they affect nutrient availability Gardening techniques for growing nutritious food, including the use of organic practices, selecting the right cultivars, and enhancing soil health to improve food quality A complete section dedicated to the best growing methods for common fruits and vegetables. Whether you're a home gardener, local food enthusiast, or small-scale farmer, Food Science for Gardeners demystifies the science of food, enabling you to put the best quality vegetables and fruits on your plate.

PLEASE When you purchase this title, the accompanying PDF will be available in your Audible Library along with the audio.

Genres: Gardening

224 pages, Paperback

Published October 8, 2024

Reviews

[Pam Dawling · Rating 4 out of 5]

Here is another concise and helpful book from Robert Pavlis in his Garden Science series, joining Microbe Science, Compost Science, Plant Science, and Soil Science, all For Gardeners. This book will help you understand food nutrients and maximize the nutritional quality and flavor of your garden produce. It provides a concise source of information on nutrition, food safety and food storage with no fluff.
Food Science for Gardeners starts with what food quality is, an intro to how gardeners can affect quality, and a brief history of food science. The opening page lists the contents of a banana: 75% water, 12% sugars, 3% fiber, 1% amino acids, 1% fatty acids, down through smaller amounts of things harder to pronounce if you never studied chemistry. This is to shake us out of any knee-jerk belief that natural foods don’t include ingredients with long chemical names.
Helping plants grow to their full potential is likely to produce more nutritious food, so continue to do that while studying the details here. Many gardeners do not test their soil for nutrient content, simply assuming the plants will find all they need. But maybe your soil is short of calcium, for example? Maybe the compost you make has a well-rounded nutrient profile. But maybe it doesn’t. We don’t test our harvested food. Did our crops get plenty of sunshine, or did it rain for a month? A high yield, fantastic taste or beautiful appearance does not measure the nutrient quality.
Calories are a measure of a food’s stored energy, which we use to function, stay within our temperature range, and continue all our chemical reactions. Calorie content is only one feature of food value.
Proteins include enzymes, antibodies, messengers and transporters. They are long chains of amino acids, folded in complex structures. Of the 20 types of amino acids making up these proteins, we can make 11, while the others (the essential amino acids) must be got from our food. Most sources of plant protein don’t contain all nine essential amino acids. As we learned from Diet for a Small Planet by Frances Moore Lappé, a combination of foods can provide complementary amino acids.
The section on carbohydrates explains that some (raffinose in dried beans) are indigestible except by the bacteria in our colons. Fiber is indigestible carbohydrate that keeps our digestive systems functioning and reduces the chance of colon cancer.
Fats are classified as saturated (solid at room temperature) or unsaturated (oils). Generally, unsaturated fatty acids are considered healthier. Getting some fats is important because they contain fat-soluble vitamins. Also, fats provide lots of energy, with 9 calories per gram compared to 4 in carbs and proteins. Our bodies can synthesize most of the fatty acids, but not linoleic acid (an omega-6 fatty acid in soybean oil, corn oil and safflower oil) or alpha-linoleic acid (an omega-3 fatty acid in soybean oil, canola oil, walnuts and flaxseed). Neither are found in meat. Olive oil and coconut oil (currently trending) have relatively small amounts.
Vitamins in some cases can be made in our bodies from previtamins/provitamins. The best-known example is beta-carotene, a provitamin A. While vitamin A is found only in animal foods, beta-carotene and alpha-carotene are found in plant foods.
Vitamins are categorized as fat-soluble (A, D, E, K) or water-soluble (C and B-complex). The fat-soluble ones can be stored in the body, but water-soluble ones are needed daily because any excess is excreted in urine. A healthy diet provides all the vitamins you can use. Taking excess fat-soluble vitamins is a health hazard, whereas excess water-soluble ones are simply a waste of money. The book details good sources of each vitamin and the benefits they provide.
A daily dose of vitamin C cannot prevent a cold. Hygiene might. Vitamin D can be produced in the body if the face (or more skin) is exposed to UVB rays from the sun for one hour or more a day. Our gut bacteria are an important source of vitamin K. B vitamins are found in many plant and animal foods, so, as always, eat a varied diet. B9, folate, can be hard for our digestive systems to absorb.
The section on minerals comes with a full-page table of what each does and where it’s found. Some can be hard to absorb if they get tied up by other nutrients. Oxalic acid in spinach and rhubarb, and phytic acid in seeds, legumes, and nuts can all bind with calcium in our gut, rendering iron non-absorbable.
Antioxidants neutralize free radicals, harmful compounds traveling around our bodies. There are many kinds of both free radicals and antioxidants, and only a matched antioxidant will neutralize a given free radical. Don’t take tons of one assuming it will fix all that ails you. Include many different ones in your diet.
The next nutrient covered is water. Our bodies lose (and need) about half a gallon (2 liters) of water each day, more in hot climates, or with vigorous activity. About 20% of this amount can come from your food. You do not need to drink 8 glasses of water a day! Another myth exploded.
Bottled water is not better than tap water (in developed areas) and has financial and ecological costs. Microplastics are tiny particles that result from plastic degradation. Bottled water can contain 325 particles per liter. Plants can absorb nano-plastics (really tiny particles) via their roots. Don’t be panicked by sensationalized accounts of whatever chemical has just been found in drinking water or breast milk. Trace amounts might not be worth worrying about, compared to other risks in your life.
A series of Nutrition Myths closes this chapter. Caffeinated beverages in moderation do not dehydrate you. Eggs don’t seem to raise cholesterol, even though they contain high levels of cholesterol. From a nutritional perspective, white sugar, brown sugar and “natural sugars” are all sucrose, none better than the others. Also, most of the sugar in honey, maple syrup and coconut sugar is sucrose, and the 22 amino acids, 31 minerals and vitamins and enzymes in honey are in such tiny amounts that they don’t provide any real nutritional value.
Not all natural chemicals are safe, not all synthetic chemicals are dangerous. Multivitamin pills are mostly synthetic chemicals. Any chemical (including water) can cause poisoning if the dose is high enough. Acute toxicity refers to a one-time exposure at a high dose. It is measured as the LD50, the dose at which half of the poor test animals die within a certain time.
Concentrated vinegar is sometimes used to kill weeds. The oral LD50 of acetic acid (the active ingredient) is 3,310 mg/kg. The oral LD50 of glyphosate, the active ingredient in Roundup, is 5,600 mg/kg. Surprising but true. The short half-life of many modern pesticides means they don’t persist for long. Some pass straight through us, some are digested. And yet, it’s wisest to minimize the amount of pesticides we eat.
Pavlis is quite accepting of GMOs as harmless, although he is only considering the effect on the diners, not the wider effects. Mostly, growing GMOs is not a worry of gardeners, as the Purple Tomato is the only GMO vegetable available to home gardeners. Most of us accepted the GMO Covid vaccines to save us from a bad pandemic. This doesn’t mean we accept all and every GMO out there.
What is nutrient density? I’ve been wondering for several years how we can know the quality of our food. Nutrient-dense foods contain vitamins, minerals, complex carbohydrates, lean protein and healthy fats, adding up to food high in nutrients while relatively low in calories. Rather vague and unquantifiable, making it difficult to make wise choices, whether in the store or when selecting varieties to grow.
Climate and soil affect the nutrients your crops contain. Some studies showed that nutrient levels in today’s food are less than they were 50 years ago. Assuming we supply organic mulches, cover crops, compost, manure and fertilizers, the soil is not running out of nutrients.
Sulfur levels in soil play a major role in the pungency of onions grown there. Too much water during growth can reduce flavor. Cucumbers get bitter if they don’t get enough water, sun or organic matter, or if temperature fluctuates more than 20F (11C), or is particularly cold or hot.
A commonly quoted study said that 43 foods show apparent declines over 50 years for 6 nutrients (protein, Ca, P, Fe, riboflavin and vitamin C), but no reliable decline for 7 other nutrients. There have been changes in cultivars over the 50 years, and the modern-day commercial focus on yield and shippability means less attention to flavor and nutrition.
We eat from hunger and because we enjoy the flavor of food. Flavor includes aroma, taste and texture, and is created in our mind from these inputs, as well as appearance. Twenty of the most important flavor compounds in tomatoes are all composed of important nutrients. Our sense of flavor and smell decrease as we age; the number of taste buds decreases after about the age of 50; our mouths become drier as we produce less saliva. Yes, food really doesn’t taste as good as it used to!
Manufactured food products have ingredients added to please us, not feed us. Sugar, salt and fat appeal to our taste buds, tricking us into eating products that are not nutritious.
Aroma depends on volatile compounds landing in our noses. People can detect more than 10,000 different smells. We can also detect odors that move from our mouth to our nose as we chew, and this may account for 80% of the flavor. Texture is perceived by the tongue, teeth and jaws. Taste incorporates five main types: salty, sweet, sour, bitter and umami. That old tongue diagram with different areas marked as having more taste buds for a certain taste has been debunked. Try it for yourself.
Sugar masks most acid flavors. People often choose a high sugar tomato thinking they’ve selected a low acid one. A tomato is low acid if the pH is above 4.6. A variety might be low-acid in one location, but in normal range elsewhere. Heirloom varieties and modern cultivars have very similar pH, with some of each having less acid. (At a pH below 4.6 Clostridium botulinum will not grow.) Catalog tags of “low acid” cannot be trusted. Search university research and extension services, looking for pH numbers rather than “low-acid” labels.
Unfortunately, there is no way to measure the nutritional value of the food you grow. Pavlis recommends focusing on growing more food, as much as you can, rather than worrying about the precise content of your produce. You will get more satisfaction and more fresh food. Which is more valuable, one carrot with 10% more vitamin A or two carrots with less? Two carrots will have more vitamin A than one carrot with a 10% increase. Eating more vegetables and fruit will make you healthier. Worrying won’t.
Because variety selection has the biggest impact on flavor, and because flavor varies from one location to another, seek advice from local gardeners and Extension office. Design your garden so that your crops are available over a long harvest period. Using varieties with fewer days to maturity brings you food sooner. Harvest vegetables promptly, and you will get higher yields over the time (for crops that yield more than a single head). Plants start to shut down once they have some seed maturing, and frequent picking removes that message to the plant. Sow more than once, to get continuous harvests without gaps. Look for warm weather and cool weather variants of the crops you like. Start crops indoors in spring, so you can transplant as soon as the weather warms enough. Use row covers, insect netting or shade cloth to give your plants extra protection. Make sure you provide all the water the crops can use.
Don’t be seduced by beliefs that heirlooms are better just because they’ve been around longer, or that open-pollinated varieties are always better than hybrids. This is magical thinking. Hybrids have been bred by agronomists seeking improvements. Higher yields or resistance to a disease that plagues your region are features worth having. But thick skins for easier shipping are not useful for home gardeners.
Sometimes the author gets a bee in his bonnet that isn’t in my bonnet. He claims that sweet potatoes are natural GMOs because they contain the DNA of a bacterium, and so people growing sweet potatoes are growing GMOs in ignorance. Frankly I don’t care if sweet potatoes contain ancient bacterial DNA. I have read in scientific papers that bacterial DNA is found in the human genome too. It’s not changing my opinion about deliberate genetic engineering. I love sweet potatoes.
Scientific testing so far does not show organically grown food to be more nutritious, safer to eat, or even tastier. A few studies show more omega-3 fatty acids in organic food. Pavlis seems to delight in busting people’s preferences for organic. But the personal health of consumers is not all that matters. Here, he does not tackle questions of the health of agricultural workers, environmental health or the degradation of land by industrial farming, especially as a result of colonization, when the social consequences as well as the environmental ones get disregarded to favor maximum profit.
Buying from trusted local farmers (organic or not) helps the local economy and brings you fresher food. Sometimes locally grown is not the most sustainable. Growing vegetables in heated greenhouses can use a lot of energy. It might be more sustainable to import from a warmer climate. Or eat different food, of course.
Some fruits continue to ripen after harvest (if not picked too immature). After harvest, the starches continue changing into sugars. They can be kept at room temperature until fully ripe, then eaten or refrigerated. Once tomatoes have passed the Breaker Stage (green with a reddish blush), they can ripen fully off the vine, tasting as good as if ripened on the plant. This can be a useful strategy to avoid predation of ripe fruit. Sometimes we want to slow the ripening, to pace the usefulness for eating or because those crops deteriorate if too mature. Carrots become bitter, broccoli yellows as the flower buds mature.
Keep produce out of sunlight or heat. Wash hands before and after harvesting. Warm water can remove all the germs, but tepid water only gets 90%. Neither soap nor dish soap (actually detergent) kills germs. The germs are merely flushed off your skin, down the sink. Don’t wear gloves – they are worse than skin for collecting germs.
Remove visible dirt asap, otherwise don’t wash until you are ready to prepare the food for eating. It is important that wash water is the same temperature as the produce, within 10F degrees (5C degrees). Cold water causes microorganisms to be sucked into the vegetables. Tap water is as effective as commercial products or “home remedy” additives such as vinegar or baking soda, which flavor the food. For crops sprayed with synthetic pesticides, try washing soda or baking soda. Avoid vinegar or salt in washing water, as these can react with pesticides to make things worse.
If you drop food on the floor, it will pick up germs in an instant, contrary to myths and contrary to the visible robust health of Julia Child on her TV cooking show. Longer time on the floor means more microbes on the food, but even 5 seconds is long enough to pick up too many.
In general, store cool-weather crops at lower temperatures (refrigerator conditions), and warm weather ones at 45-55F (7-13C). Crisper drawers are not decorative! They keep the contents more enclosed, and more humid, than the body of the fridge.
There is a table of storage conditions, divided by room or fridge temperature, whether the crop continues ripening after harvest, whether it produces ethylene and whether it is sensitive to ethylene. No numbers, very easy to follow.
The chapter on preserving food stresses the importance of preserving freshness, flavor and nutrition while also preventing the food from spoiling. Benefits must be balanced with the negative effects. The University of Minnesota has great food preservation info.
No single preservation technique is best for all crops. Freezing stops bacterial activity but does not kill all microbes or enzymes. Boiling or blanching destroys enzymes and kills most microbes. Pressure cookers can kill microbes that survive beyond normal boiling point up to 248F (120C). Pickling (adding acids) and fermentation (producing alcohol) can kill some microbes and deactivate enzymes. Smoke adds formaldehyde, which has negative effects on microbes (and people). Sugar and salt can preserve food by drawing water out of the food cells and killing bacteria. Fungi can continue growing in high sugar or salt environments.
Water bath canning (for produce with pH below 4.6) and pressure canning (for low acid foods above 4.6) are great ways to preserve food without electricity. In a pressure cooker at 30 psi, water boils at 121F (250C), hot enough to kill all microbes. A chart sets out how to can 14 different foods in quart jars, either using a water bath (when appropriate) or a pressure canner.
Food drying (mysteriously now called dehydrating) is simple. Dried food cannot harbor microbes or enzymes. Food drying needs to happen slowly, at a fairly low temperature. If you need to dry food faster, slice it thinner. Do not try drying fatty foods.
Fermentation converts molecules such as starches and sugars into organic acids and alcohols, via either lactic acid fermentation or alcoholic fermentation. Lactic acid fermentation is mostly a bacterial process. It is used for pickles, sauerkraut, yogurt and cheese. Alcoholic fermentation is carried out by yeast, fungi and some bacteria, producing yeasted bread, wine and beer.
Pickling uses vinegar, water, salt and sometimes sugar. It gives an acidic flavor. Don’t reduce the salt in pickle recipes – it needs to be there. Only fermented pickles provide probiotics. Fermentation also reduces toxins in the food, such as phytic acid in soybeans.
Packing food in oil is not a safe way to preserve vegetables. Botulism can grow quite well in oil. Pasteurization normally destroys pathogens. This is useful for milk and fruit juices.
The closing chapters cover cooking food and growing it. There are tips on eleven specific vegetables, and that chapter is necessarily short. This is not a gardening book, but a food book with some gardening tips. Anyone reading this book for growing pointers would likely be disappointed. The book’s strengths lie in the information on nutrients in food, which is presented clearly and concisely and is hard to find elsewhere.

[Breanna · Rating 4 out of 5]

An invaluable educational resource for gardeners with the desire to increase their scientific knowledge and understanding of the food they grow. The information is well organized and easy to digest, but could benefit from some visual formatting and images. Even textbooks are more visually appealing to read, despite the dense material.

Thank you to New Society Publishers for providing an advanced copy of this book in exchange for my honest review.