In the processing industry, apples are often used for the production of sauce and juice, but can also be processed into other products, such as cider and cider vinegar. Cider and vinegar are both produced by fermentation.
Cider is an alcoholic beverage made from fermented apple juice (at least in England). However, in the US, ‘cider’ meant rough apple juice while ‘hard cider’ is the fermented stuff. Various types of apples are needed to make well-blended cider.
Fermentation is the basis of Vinegar processing. During alcoholic fermentation, yeasts utilize sugar in apple juice to produce ethanol, an anaerobic process that results in cider. The production of vinegar involves an additional aerobic fermentation step, where acetic acid bacteria convert ethanol in cider into acetic acid. The sensorial characteristics of cider and vinegar depending on the fermentation processes of microorganisms and the selected processing techniques.
The process of manufacturing Apple cider vinegar completes in the following steps-
- Harvesting: Harvesting is done between September and December. The manual collection is done by sacks, and more extensive orchards are harvested mechanically.
- Selection of Apples: Apples should be firm and ripe. Green, under mature apples, cause a flat flavor.
- Sweating: It is an optional mellowing period, the apples are stored in a clean, odor-free area, sometimes they are allowed to mellow and soften for about a week to ten days before grinding
- Washing: After the apples have mellowed, they must be washed to remove leaves, twigs, insects, spray residues, and harmful bacteria. They are automatically poured out from the bins onto a scrubber. This machine rinses and scrubs each apple, removing most chemical residues from the skin. From there, they are moved along a conveyor to a hopper filled with water. From the hopper, the apples are put on a conveyor and moved to another worker. Jets of water aid in moving the apples to ensure proper cleaning.
Note- Only whole apples are used during manufacture because they have not been exposed to oxidation’s flavor-damaging effects. This means that each apple is inspected and any rotten or moldy fruits are removed. Since many different factors can negatively affect cider taste, cleanliness is essential during manufacturing.
5. Grinding: As apples are a hard fruit, slicing is necessary to facilitate juice extraction. This is done with high-speed rotary blades, which reduce the fruit to a pulp or the apples are put in a large mill and ground to a fine pulp with applesauce consistency. It is done to ensure that the maximum amount of juice can be extracted from the apples.
6. Pressing: To extract the juice from the mash, three main types of presses are used in the commercial production of apple juice; the hydraulic press, the screw press, and the belt press. Unlike the hydraulic press, the screw press is operated continuously and has a high working capacity. Two additional types of presses are the bladder press and the basket press. These are mainly used in small and medium-scale production.
7. Pasteurization: It is done around 92°C for 10-15 sec. It is done to kill all the unwanted microorganisms.
8. Cooling and Filling: The juice expelled from the pomace is pumped through plastic tubes to a cooling tank. As the cider is transferred to the cooling tanks, it is passed through a screen mesh to remove any pulp pieces from the liquid. It is then chilled and stored at 33° F (0.6° C). This helps to inhibit the contamination by undesirable microorganisms. Preservatives such as potassium sorbate are added and the juice is sent off to the fermentation tank.
9. Fermentation: The apple juice ferments for eight weeks often in two stages This includes classical alcoholic fermentation of sugars into ethanol performed by yeast strains followed by acetobacter fermentation to produce vinegar.
Note- Sometimes malolactic fermentation (MLF) occurs by lactic acid bacteria (LAB) during maturation. Malic is the principal acid in apple. It is decarboxylated by lactic acid bacteria to give CO2 and lactic acid. Hence the acidity falls by 50% and the cider becomes slightly carbonated
10. Racking off: Using a clean plastic tube, the cider is drained off into the second fermenting tank or directly into bottles.
11. Filtering or fining: This step makes a cider crystal clear. It can be done by:
a) Using a closed filter system to avoid exposing the cider to air.
b) Mixing gelatin, bentonite, and a pectic enzyme into the cider to clear unwanted
12. Aging and Bottling: Ageing is done in oak barrels to enhance the flavor. Use sterile bottles for cider. For an “in-bottle fermentation” a small amount of sugars may be added to each bottle. Cap or cork the bottle and then pasteurize the cider to prevent further fermentation. To avoid killing the yeast by pasteurization after adding sugar, the addition of sulfur is most practiced.
13. Storage: The bottles should be kept in a cool, dark storage place.
Process Chart :
Difference between Cider and Apple Juice.
Cider- Raw apple juice that has not undergone a filtration process to remove coarse particles of pulp.Cider contains more of apples’ polyphenol compounds
Apple Juice- Apple juice undergoes filtration to remove pulp and is then pasteurized to extend the shelf life. It contains less polyphenol compounds than cider
Cider is made from fermenting apple juice, which relies on natural yeast present in the apples for fermentation. In the United States, fermented alcoholic apple juice is called “hard cider,” while freshly pressed, nonalcoholic cider is called “sweet cider.” It contains acetic acid and nutrients such as B vitamins and vitamin C.