Sucrose

Sucrose is one kind of organic compound which can be found naturally in sugarcane, sugar beets, sugar-maple sap, dates, and honey. It contains carbon, hydrogen and oxygen atom with the general formula of C₁₂H₂₂O₁₁. Actually, it is the product 50:50 of combination of two monosaccharide molecules, glucose and fructose joined by the glycosidic linkage.

Both of the glucose (aldehyde) and fructose (ketone) taste sweet. Sucrose (disaccharides), the combination of glucose and fructose takes on the properties of non-reducing sugar, water soluble, colourless and sweet-tasting crystal. During the process of fermentation, chemical anaerobic process takes place. Microorganisms including bacteria, yeast and mould degrade carbohydrates like sucrose into acid or alcohol with the absence of oxygen and the exclusion of a water molecule.

Lactobacillaceae, one kind of acetobacter species has the ability to utilize sucrose and produce alcohol as the product and it is usually coupled with adenosine triphosphate (ATP) production. However, sucrose is not fermentable by lactobacillaceae directly. Sucrose fermentation must be initiated by the cleavage of sucrose hydrolase to glucose (major source of energy) and fructose through a process of hydrolysis. Once the glycosidic linkage is broken down, the glucose and fructose can be consumed directly and fermented multiply by these bacteria as a source of energy. When these microorganisms metabolize and grow, they eventually release by-products such as ethanol and carbon dioxide whereby these by-products play an important role in preserving and changing the texture and flavor of the food substrate. 

Citric Acid

Citric acid is a colourless, crystalline organic compound belonging to the family of carboxylic acid. It is a slightly stronger acid than typical carboxylic acids because the anion can be stabilized by intramolecular hydrogen-bonding from other protic groups on citric acid. It is odourless with a strongly acidic taste, naturally occurring weak organic acid that exists in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8 percent of the dry weight of the fruit. With the molecular formula C₆H₈O₇ , it is known that citric acid is made up of six carbon atom, eight hydrogen atom and seven oxygen atom. Citric acid's mild acidity is the result of three carboxyl groups (three compounds made up of a carbon atom bound with two oxygen and one hydrogen atoms). Its 2D structure and 3D conformer are as shown:

                             

Citric acid has many uses including act as a flavor enhancement, bacterial inhabitant, pH adjustment, and as an antioxidant. During the fermentation of fruits in the preparation of fruit enzyme, lemons which rich of citric acid are used so that the pH will be low enough to safeguard against infection. If the pH is high without lemons, the fermentation will be susceptible to bacterial infections. Besides, citric acid stabilizes sweets and confectionery, thus it is able to prevent crystallization of sucrose during fermentation.

Why apple turn brownish??

Oxygen is metabolized by the cells on the fruit's surface (oxidation). Free radicals are formed-- these are atoms with unpaired electrons. Having an unpaired electron makes them really unstable, so they attack surrounding stable molecules and steal electrons. This initiates a domino process of electron stealing and eventually causes cell damage. Hence, as an antioxidant, citric acid has extra electrons, so they bind to free radicals, neutralizing them by donating one of their own electrons. That domino chain of free radicals stealing electrons cannot occur. In other words, citric acid can be used in food industry to prevent browning of fruits and vegetables. It lowers the pH of the fruit tissue to retard the action of the phenolase. If the pH is reduced below 3.0, the activity of the phenolase will be severely inhibited.

Ascorbic Acid

Pineapple, as one of main ingredient in the making of pineapple drinking enzyme has vitamin C content of about 36.2mg per 100g serving. Vitamins are organic compounds. Vitamin C or L-ascorbic acid is an essential nutrient for humans and certain other animal species. Vitamin C is a water-soluble vitamin that is necessary for normal growth and development. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

Formula: C6H8O6

Molar mass: 176.12 g/mol

Melting point: 190 °C

Soluble in: Water

IUPAC ID: (R)-3,4-dihydroxy-5-((S)- 1,2-dihydroxyethyl)furan-2(5H)-one, 2-Oxo-L-threo-hexono-1,4-lactone-2,3-enediol

Ascorbic acid resembles the sugar from which it is derived, being a ring with many oxygen-containing functional groups. The molecule exists in equilibrium with two ketone tautomers, which are less stable than the enol form. In solutions, these forms of ascorbic acid rapidly interconvert.

Nucleophilic attack of ascorbic enol on proton to give 1,3-diketone

Tautomeric equilibrium – Vitamin C is sensitive to heat and light, and will oxidize readily by reacting with the oxygen in the atmosphere. Therefore, the fermentation of pineapple enzyme should be carry out in cool and shady places and the glassware must be tightly close.

While Vitamin C does not have an acid or carboxyl group, it does have acidic hydrogen, hydrogen that can be easily removed. Since Vitamin C has acidic hydrogen, it can behave like a weak acid when dissolved in water or when reacted with other compounds.

Function of Vitamin C:

Vitamin C is needed for the growth and repair of tissues in all parts of your body. It is used to:

Form an important protein used to make skin, tendons, ligaments, and blood vessels

-Heal wounds and form scar tissue

-Repair and maintain cartilage, bones, and teeth

Vitamin C is one of many antioxidants. Antioxidants are nutrients that block some of the damage caused by free radicals.

-Free radicals are made when your body breaks down food or when you are exposed to tobacco smoke or radiation.

-The buildup of free radicals over time is largely responsible for the aging process.

-Free radicals may play a role in cancer, heart disease, and conditions like arthritis.

Vitamin C boosts our immune system.

-Vitamin C is found in high concentrations in immune cells, and is consumed quickly during infections

-It has been hypothesized to modulate the activities of phagocytes, the production of cytokines and lymphocytes, and the number of cell adhesion molecules in monocytes

For many years, vitamin C has been a popular remedy for the common cold.

-Research shows that for most people, vitamin C supplements or vitamin C-rich foods do not reduce the risk of getting the common cold.

-However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms.

Vitamin C deficiency:

Vitamin C plays an important role in maintaining our health. It is a cofactor in at least eight enzymatic reactions including several collagen synthesis reactions that, when dysfunctional, cause the most severe symptoms of scurvy.

Side effects:

Serious side effects from too much vitamin C are very rare, because the body cannot store the vitamin. However, amounts greater than 2,000 mg/day are not recommended because such high doses can lead to stomach upset and diarrhea.