General descriptions
Potato is the fourth most important food crop in the world after rice (Oryza sp.), wheat (Triticum sp.), and maize (Zea mays). It is the only major food crop that is a tuber that accounts for one hundred and thirty kilocalorie of energy per day. It is found that the kilocalorie of the potato in a developed country is about three times that of the potato in developing countries where it is still considered a vegetable.
Potato is an economically important staple crop prevailing worldwide with successful large-scale production, consumption, and affordability with easy availability in the open market. Global potato production is estimated at three hundred seventy million tons in about seventeen million hectares, and the output in the Americas was forty-five million tons which were reviewed in 2021. Potato is native to South America and one of the most widely eaten vegetables. It is scientifically known as Solanum tuberosum. They are two major subspecies of Solanum tuberosum andigena or Andean and Solanum tuberosum Chilean.
There are over one thousand and four hundred species in this genus, including trees, shrubs, annuals, biennials, perennials, and climbers from various habitats worldwide. Some are evergreen, others semi-evergreen or deciduous. The genus includes essential food plants like the potato and eggplant, though many species are dangerously poisonous. Some of the ornamental species from this Solanaceae are grown for their flowers and fruits. There are about five thousand potato varieties worldwide. In addition, three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile, and Colombia.
There are six broad categories of potatoes, namely baking potatoes, white potatoes, yellow-fleshed potatoes, red-skinned potatoes, purple potatoes, and sweet potatoes. Baking potatoes are those large, brown-skinned, white-fleshed, high-starch, oval potatoes that are not necessarily just for baking. Then, white potatoes are either long, thin, or pudgy round white potatoes, the latter sometimes called boiling potatoes. Their skin is pale white or beige, somewhat translucent, not harsh or earthy. White potatoes range from medium-starch to slightly waxy in texture.
Besides, yellow-fleshed potatoes are the medium-starch potatoes that are now common in markets across the country. Their skins may be yellow, golden, or just slightly beige. However, the flesh is always yellow. Red-skinned potatoes with red skins are low starch and have a waxy texture. They are often baked or roasted, which works well in soups because their low starch softens without clouding the broth.
Furthermore, purple potatoes are probably the closest to the original potato. A bit of a rarity, purple potatoes have begun showing up across the United States, particularly in Latin American and Mexican markets, thanks to the increased production in California. Their skins are usually purple, or perhaps blue or even lavender, in which the flesh may or may not be so colored. Lastly, sweet, orange-fleshed potatoes can run the gamut from white to red, from moist to dry. The varieties include Red Garnet and Jewel. White-fleshed sweet potatoes are the rarest and most popular in some Asian dishes.
Horticultural practices
The leaves are arranged alternately, while the showy flowers are solitary or in clusters, star-shaped to bell-shaped, ranging in color from white and yellow to blue and purple. The fruits are berries that contain many seeds. Potatoes are tubers that are range in size, shape, color, starch content, and flavors. Some famous mature and large-size potatoes varieties include the Russet Burbank, the White Rose, and the Katahdin. Furthermore, the Red LeSoda and Red Pontiac are two types of new potatoes that must be harvested before maturity and are much smaller. Other varieties are available that feature purple-grey skin and beautiful deep violet flesh. However, the popularity of potato cultivars varies with geographical region.
Potato plants have a shallow rooting system, making them very sensitive to water stress, requiring proper water management to avoid putting potato plants under drought conditions. Potatoes are grown under different irrigation methods such as surface irrigation, drip irrigation, and sprinkler irrigation. To sustain and optimize potato production, moisture should be kept above fifty of the total available water of the site soil. Potato tuber number per plant and total yield increase with adequate irrigation management after tuber initiation increases the size of tubers.
It is a root vegetable, which can be scatter grown throughout the garden. It is a perennial plant that grows to thirty inches with a spread of eighteen inches. It has an erect, hairy, green, and large stem up to fifteen inches. The potato plant has dark green leaves with three to five pairs of heart-shaped leaflets. It produces flowers in pendent clusters of white or pale violet flowers. The developmental stage influences the phytonutrients content of potatoes. This plant requires a warm climate with a wide range of requirements that most of the species of this family prefer full sun and rich and well-drained soil.
Propagation
Potatoes are commonly grown from seed in spring or cuttings in the summer. They are being propagated most of the time by cutting the microtuber or part of the potato with buds. Many countries lack isolated and vector-free growing areas that permit the production of quality potato seed tubers to consider microtuber technology a vital component of seed potato production. Microtubers may provide a solution in countries where their availability of high-quality seed tubers forms a constraint due to explosive increases in new potato-growing areas. Potatoes have sprouts formed from the ‘eyes’ of the potatoes where the tubers stem and sprout new plants.
With the aid of biotechnology, microtubers are used as the explants in plant tissue culture. Through meristem cultures, virus-free minitubers are produced, which then can be directly field-planted after acclimatization at the nursery. Plant tissue culture halved the field time, three to four years compared with seven or more years from conventional propagation to supply commercial growers. Advanced cloning technology also significantly improved seed tuber quality with fewer viral, bacterial, as well as fungal problems.
Pests and diseases
They are prone to attack by a spider mite, white fly, and aphids. Irrigation management is critical for managing fungal and bacterial diseases in potato crops such as hollow heart, late blight, early blight, white mold, bacteria stem rot, early drying, and bacterial ring rot. Irrigation can ‘create’ a favorable environment for potato soil-borne diseases such as Rhizoctonia canker and black scurf (Rhizoctonia solani), common scab (Streptomyces scaviei), powdery scab (Spongospora subterranean f. sp. Subteranean), white mold (Sclerotinia sclerotiorum), silver scurf (Helminthosporium solani), pink rot (Phytophthora erythroseptica), and Verticillium wilt (Verticillium dahlia). This is because sprinkler irrigation is an overhead irrigation method that creates high humidity on the potato leaves and within the canopy, creating a micro-climate favorable to the development of potato foliage diseases such as early blight, late blight, bacterial stem rot, as well as white mold.
Therefore, it is vital to allow foliage to dry between irrigation and late afternoon and early evening irrigation events keep leaves wet during the night, which may increase the potential of late blight, which should be avoided. Various diseases in potatoes are transmitted by mostly phytophagous pests feeding on the vascular system of the potato plant. For example, the potato psyllid (Bactericera cockerelli) is one of the most critical pests in potatoes due to its feeding behavior and the transmission of a bacterium that causes zebra chip diseases, altering the quality of the potato tuber and the fried potato chips of French fries.
In addition, aphids, especially the green peach aphid (Myzus persicae) and potato aphid (Macrosiphum euphorbiae), transmit potato leafroll virus, which reduces marketable potato yield causing phloem net necrosis (a brown discoloration) inside the potato that reduces quality and other cucumber mosaic and alfalfa mosaic (calico) viruses inducing a wide variety of foliar and tuber symptoms. Moreover, Potato Virus Y (PVY) is transmitted through vectors like Myzus persicae, Rhopalosiphum padi, Aphis fabae, and other vectors. Spider mites are abundant under severe drought and hot conditions, and they colonize stressed plants under poorly managed irrigation scheduling. The potato tuberworm (Phthorimaea operculella) is a significant pest in potatoes that feed on potato leaves with less important yield lost, and tuber infestation reduces the marketable product.
Furthermore, there is typical damage to the potato tubers by the larvae mine leaves, stems, petioles, and excavate tunnels. Once the potatoes have been harvested and kept in storage, the period generally increases total phenols content in potatoes. The optimal temperature of postharvest storage for potatoes is four or twenty degrees Celsius.
Nutritional facts
Potato is a very efficient food crop and produces more dry matter, protein, and minerals per unit area than cereals. Potatoes provide essential nutrients like carbohydrates, dietary fiber at its peel, several vitamins (such as vitamin A in the form of β-carotene and C), and minerals such as potassium, magnesium, as well as iron. It contains mostly water, and sixty to eighty percent of the solid is indigestible substances, which is of no nutritional value to humans. It is, therefore, that potato is processed before eating. Apart from being a rich source of starch, potatoes contain a good quantity of small molecules and secondary metabolites, which play an essential role in several processes. Potato also contains several phytochemicals such as phenolics, flavonoids, polyamines, and carotenoids, which are highly desirable in a diet because of their beneficial effects on human health.
By nature, potato does not add much fat to the diet but are flat and less tasty. Hence, edible potato products require the addition of fat salt to make them delicious and highly desirable. However, one needs to take extra health concerns, especially for obesity and other related health issues. It is essential to use the heat in the preparation of potato dish is almost between the endogenous chemicals like reducing sugars and amino acids. The most common and highly desirable reaction for the aromatic and tasty product is the Maillard reaction, which is a reaction between sugar and amino acid.
Potatoes contain water-soluble antioxidants that act as free radical acceptors, such as glutathione, ascorbic acid, quercetin, and chlorogenic acid. They are a good source of carotenoids (yellow color of the tuber flesh), lipophilic compounds synthesized in plastids from isoprenoids. Polyphenols found in the potatoes are highly concentrated, considered the third most important source of phenols after apples and oranges. The phenolic content of the potatoes reported is lignin, coumarins, anthocyanins, flavones, tannins, monohydric phenols, and polyhydric phenols present in both skin and flesh of the potatoes.
Loss of nutrients during processing is a significant concern, and it is necessary to minimize nutrient losses during the processing of potatoes into various products. Research had found that the antioxidant capacity of baked-, boiled, microwaved-, or steamed-potatoes was reported to be higher than uncooked potatoes, and the highest values were observed for steamed or baked potatoes.
The phenolic compounds found in the peel or skin are higher than in other parts of the potatoes. The levels of antioxidants were reported to vary with the flesh color of potatoes. Boiling and baking potatoes with the peel is a suitable cooking method as it helps retain most nutrients. Therefore, the peels of the potatoes that will be discarded as waste can be used in downstream products for callus addition in different food products.
Toxicity
Raw potatoes should be firmed to the touch with tight skin free of giant bruises, black spots, or other blemishes. If a potato has become soft or mushy, one should discard it. Though it is normal for potatoes to smell earthy or nutty, a musty or moldy odor is a hallmark of spoilage. However, a potato might have a blemish or bad spot on the inside that we cannot see from the outside. A strong smell coming from an otherwise fresh-looking potato is a warning sign that the interior may have rotted or started to mold. One should dispose of foul-smelling potatoes.
A chemical reaction and the product are highly dependent on the nature and abundance of constituents during the process. This could lead to the production of highly undesirable toxic substances like acrylamide in high-temperature baked products derived from high starch and proteinous raw material. Potato is one such raw material that has been shown to produce acrylamide in large quantities when processed at elevated temperatures. The significant problems during potato storage are sprouting and rotting due to disease. Different protocols for prolonging the period of tuber dormancy have been tried.
The shoots, haulms, and leaves of the potato contain appreciable amounts of an alkaloidal glucoside, which is solanine. The sprouts also contain chaconine and other toxic glycoalkaloids apart from solanine. This alkaloidal glucoside may accumulate in the tubers themselves, which may be present in sprouting potatoes in quantity sufficient to cause severe poisoning under certain conditions. Health problems linked to eating sprouted potatoes range from stomach upset to heart and nervous system problems and even death in extreme cases. The symptoms after having sprouted potatoes are reported, namely vomiting, diarrhea, colicky pains, headache, depression, and so on. They may also increase the risk of congenital disabilities. The majority of the cases were severe, although all the people affected ultimately recovered. Although sprouts may look unappealing, recently sprouted potatoes are still safe to eat as long as the sprouts are removed by simply snapping them off with your fingers.
One of the best ways to reduce sprouting in potatoes is to avoid stockpiling them and only buy them when planning to use them. This might be due to the presence of moisture trapped between the potatoes, which stimulate the formation of the sprouts. In addition, discarding damaged potatoes and ensuring that the remaining ones are dehydrated before storing them in a cool, dry, and dark place may also reduce the likelihood of sprouting.
Downstream products
Starch is the primary carbohydrate in potatoes and is an agriculturally important commodity with many food and non-food uses. Potato starch is used in various products like food ingredients or as an industrial material. Potato starch is a mixture of two polysaccharides, amylose and amylopectin. The starch content of potatoes is about fifteen percent on a fresh weight basis. However, the starch content on a dry weight basis is ranged around eighty percent. Potato starch from various cultivars typically contains twenty to thirty-three percent amylose on a total starch basis, with the balance being amylopectin.
Furthermore, the starches are modified physically through heat-moisture treatment, annealing, pre-gelatinization, high-pressure treatment, and chemically via cross-linking, substitution, acid hydrolysis, and oxidation extend the range of starch applications in the food and non-food sectors. The molecular organization and interactions of potato starch with non-starch polysaccharides and sugars influence sensory attributes and shelf life of potato products like mashed potatoes, French fries (chips), and potato chips (crisps).
Potato chips (crisps) are skinny slices of potatoes (about one millimeter), deep-fried at around one hundred and eighty degrees Celsius until they were dry and brittle, with a finished moisture concentration of 1.3-1.5 percent to ensure the stability of crispness in the product. They are fried in different types of vegetable oil with a range of added flavors. Global manufacturers of chips and other processed products have mostly eliminated trans-fats (saturated oils) and are launching a range of low-fat and fat composition changes to meet the challenge.
French fries are made from potatoes that have been cut into thin strips (around one centimeter square in cross-section), washed briefly in cold water, partly dried to remove surface moisture, and deep-fried in vegetable oil at approximately one hundred and eighty degrees Celsius to a light golden color. The final product comprises around ten percent fat, most of which is retained on the surface. Frozen fry manufacturers ship their products raw, par-fried, or partially cooked and drizzled with oil for baking to suit the end-user. The product is frozen at negative forty degrees Celsius and stored at negative twenty degrees Celsius. The moisture content needs to be less than seventy percent in par-fried fries to prevent limpness and separation of the interior and the crust. Heterogeneity in moisture content between strips can result in variability in texture. Frying is finished by immersing the frozen product in deep fat at about two hundred degrees Celsius until the desired color and texture are achieved.
Other frozen potato products include waffles, wedges, hashed brown potatoes, rosti, pre-formed mashed potatoes, patties, potato rounds, diced potatoes, baby roasts, and a variety of shaped potato products child-appeal.
