Introduction

In the twentieth century, there was a need to identify the substance whose deficiency causes scurvy, also known as hypovitaminosis C. This led to the identification of vitamin C. Early researchers found that a deficiency in ascorbic acid (vitamin C) resulted in the manifestation of scurvy along with other conditions.

This is because scurvy predisposes patients to further infections due to weakening the immune system, especially in the respiratory tract. In the 1900s, it was discovered that the administration cured the breakout of pneumonia with ascorbic acid treatment in individuals affected. This treatment regimen contained what would later be known as vitamin C (ascorbic acid).

White blood cells have a higher vitamin C content, unlike plasma content. Studies show that they play an influential role in phagocytosis, viral replication, production of interferons as well as in the life cycle of T-lymphocytes. This shows that vitamin C plays an essential role in immune defence.¹ 

The immune system is made up of many cells, tissues, organs and systems that have over time been programmed to guard the host from invading pathogenic organisms such as fungi, viruses and bacteria and mutagenicity such as in cancer cells. These defence systems interact in complex ways and they all play essential roles in the function of protecting the bodily functions. Humans are unable to synthesize vitamin C because an important enzyme is lost in the biosynthetic pathway. 

A deficiency in vitamin C predisposes the sufferer to scurvy which is manifested as lowered immunity, weakened collagenous structures, and inadequate wound healing. People who suffer from scurvy tend to stand the risk of suffering from even more debilitating and life-threatening infections like pneumonia. Vitamin C is a water-soluble vitamin, therefore, storage in the body is challenging.

A specific and continuous dosage through ingestion of vitamin C is essential to prevent hypovitaminosis C. Vitamin C is essentially an antioxidant and it can donate electrons which is essential to protect biomolecules such as lipids, proteins, carbohydrates and nucleic acids in our body from oxidative stress.²

Benefits of vitamin C

The benefits of vitamin C (ascorbic acid) are numerous. It is an essential component of the human diet and necessary for the maintenance of human health and immune function. The mechanism of action of vitamin C includes its ability to serve as a reducing agent during hydroxylation reactions. Similarly, it serves as an antioxidant due to its ability to remove harmful oxidizing agents and free radicals.

Vitamin C is an important component necessary for collagen synthesis. Studies have shown that the deficiency of vitamin C causes the abnormal formation of dentin on the teeth, consequently, the teeth become weak and at a higher risk of decay and mechanical injury. Collagen is also important for the formation of cartilage, bones and scar tissue.

Additionally, the synthesis of carnitine, an essential compound important for the transportation of fatty acids into the cells to be oxidized to supply the needed energy, requires vitamin C to facilitate its synthesis. Also, some hormones are activated by vitamin C such as bombesin, calcitonin, corticotrophin, gastrin, and growth-hormone-releasing factors. Moreso, vitamin C has been shown to aid some drug metabolic processes such as the liver flavin monooxygenase system.

This process serves as a scavenger of harmful free radicals, helps with the prevention of DNA mutation, and protects against oxidative damage which is usually present due to normal metabolic processes of the body. This relieves the human body of oxidative stress which has been proven to be involved in the pathogenesis of many morbid physiological conditions as well as exposure to environmental pollutants. Vitamin C along with other antioxidants have been shown to provide these antioxidant benefits.

Vitamin C facilitates iron absorption by keeping ferric ions in their ferrous forms. It forms soluble complexes with ferric ions, ensuring iron remains soluble even in the alkaline pH of the duodenum. Other benefits of vitamin C include anti-cancer properties from its anti-inflammatory effects which helps prevent DNA mutation caused by the oxidation processes. Vitamin C also has some cardioprotective properties because it prevents the programmed death of endothelial cells.³

Vitamin C content of pineapple

Pineapple (Ananas cosmosus (L.) Merr. Family: Bromeliaceae) is one of the most popular commercial fruits globally. It is popular for its pleasant taste and flavour which can be attributed to the sugar and citric acid present in the fruit. It can be consumed fresh, cooked or juiced. Apart from bananas and citrus, pineapple is the most popular seasonal fruit in the world.

Though it is quite perishable it can be preserved. Some important global producers are China, Brazil, the Philippines and Thailand. Others are Nigeria, India, Kenya and Mexico among others. Pineapple has immense health benefits and contains carbohydrates, vitamin C, potassium, calcium, fibre and water. It has minimum sodium and fat content. The moisture content of pineapples ranges from about 82 to 86 % and solid content (consisting of sucrose, fructose, and glucose) between 13 to 19 %. Pineapple is a great source of vitamin C which has been shown to protect against viral and bacterial infections.

It is also an effective antioxidant and aids in iron absorption. A ripe pineapple can supply up to 16.2 % of the daily minimum dietary requirement of vitamin C: a powerful antioxidant that protects the cells from damage and improves the formation of collagen in bones, cartilage and muscles. It reduces the risk of certain cancers and also reduces the incidence of urinary tract infections in pregnant women, promotes healthy skin appearance, reduces metal poisoning and protects oral health.^4,5 

Storage and preservation tips for vitamin C

After the harvesting season, a significant amount of pineapples may be lost to spoilage during the off-season and due to a lack of adequate preservation methods. Spoilage is usually due to its high moisture composition. Dehydration and drying are considered as one of the best and most popular ways to preserve pineapples. The other methods of preservation are usually not as cost-effective and may even require sophisticated technology and machinery.

Dehydration involves the removal of water content in food materials to ensure that the environment is inhabitable for microorganisms. As long as the food retains its healthy colour, texture, flavour, and most importantly, its nutritive value when rehydrated, it is considered acceptable. However, the method of drying and reconstitution must be carefully chosen to ensure that the integrity of the food product is preserved. This is due to the sensitivity of pineapple to heat and moisture especially because vitamin C is water soluble.

Air dehydration can be carried out on pineapples, however, the fruit slices must be pre-treated first preferably with sucrose-osmosis also called osmotic dehydration to prevent degradation of the vitamin components. Osmotic dehydration is carried out on fruits and vegetables through the immersion of the fruit in hypertonic solution (osmotic solution) which has a high osmotic pressure and a low moisture activity. This provides a force for water removal between the solution and the food item.

The plant cell wall therefore acts as a semi-permeable membrane. Direct osmosis has been said to save energy and help preserve the integrity of food products. Another method of fruit preservation is the production of jam which is very nutritious and palatable. It has become one of the most popular components of many diets globally. Jams can be homemade or industrially produced.⁶

Summary

Pineapples are made up of many beneficial vitamins and minerals. It is an important source of vitamin C which is vital for normal immune functions of the body. Studies show that one pineapple fruit provides as much as 16.2% daily requirement of vitamin C for humans. The fruit must be appropriately preserved using processes such as drying or dehydration and processing into jams to ensure its quality and nutritional benefits.