In collaboration with Dr. Eleonora Roncarati
(6) Prevention of fermentation or PASTEURIZATION
The prevention of fermentation presents further technological problems. This is the only microbiological alteration that honey can undergo and is due to the presence of yeasts that find their ideal development environment (osmophilic yeasts) in the concentrated sugar solutions.
The first method consists in implementing all possible precautions to try to extract only honeys with a water content of less than 18.0%. If this is not possible, various techniques exist to reduce the water content of too wet honey by means of forced evaporation. They are easier to make on honey still contained in the combs, when the surface / mass ratio is favorable for a rapid exchange of humidity with the surrounding environment.
Good results are obtained by circulating a stream of hot air (at a temperature not exceeding 35 ° C) produced between the combs contained in the superstructures, produced with a suitable system (boiler, fan and thermostat); in 24 hours humidity decreases of 1 - 3%. It is essential to dispose of the air charged with humidity that comes out of the stack of honeycombs subjected to the procedure with a suitable suction system. Similar results can be obtained with dehumidifying machines (which remove humidity from the environment). In this case the supers are to be placed in a reduced environment and isolated from the outside air, so that the dehumidification process takes place against the honey and not the external environment. Both systems can be adapted to the concentration of honey already extracted from the combs: in this case a structure must be constructed that allows honey to be properly exposed to the current of warm air (which may be warmer than the temperatures imposed on the treatment of honey in honeycomb) or to the dry environment generated by the dehumidifier. Honey, for example, can be slid over an inclined plane, or made to fall into thin rivulets or distributed on the surface of rotating discs or continuously mixed.
The last industrial alternative is the use of vacuum concentration plants, adapted from those commonly used in the canning industry for vegetable juices (fruit juices, tomato concentrate, jams), which can operate extremely efficiently at temperatures lower than 45 ° C. Honeys concentrated with these systems, if well used for products in which the fermentation process has not yet begun, do not undergo significant degradation.
The other family of fermentation prevention systems is based on the inactivation of yeasts. The inactivation of the yeasts is done with heat (pasteurization): to destroy the osmophilic yeasts it is necessary to heat at 60 - 65 ° maintained for a few minutes. Similar treatment conditions can be implemented only with industrial systems that allow a rapid heat exchange in order to keep the honey at a high temperature only for the strictly necessary time (thin layer heat exchangers, tubes or plates). Generally these pasteurization processes are carried out with the dual purpose of preventing fermentation and favoring the conservation of honey in a liquid state: in this case, the treatment is carried out at a temperature of 77-78 ° C for 5 - 7 minutes, immediately before dell'invasettamento.
(7) The preparation of liquid honey
The preparation of honey for the market must confront the natural tendency of many honeys to crystallize. On a commercial level, producers face the problem in various ways.
If the appearance of honey is not a limiting factor, no special measures are taken and the honey is marketed as spontaneously; it is however useful to try to avoid that the product undergoes evident transformations during the marketing period (for example that it crystallizes during marketing), as every change is seen by the consumer with suspicion; furthermore it is carried out outside the manufacturer's control. For other markets, honey is rigorously presented in liquid form and, for this reason, it is often necessary to refound it or treat it to prevent crystallization.
Alternatively, an attempt is made to accelerate the crystallization in order to be able to present it constantly and with pleasing characteristics both in terms of appearance and use.
Some honeys, on the other hand, remain naturally liquid for a long time, for example if their glucose content is naturally low (robinia honey, chestnut honey, fir honeydew) or if the water content is high or if they are kept constantly at temperatures above 25 ° C. These last two conditions are however in contrast with a good preservation of the product and are therefore not usable to prolong the life time in the liquid state.
Among the solutions commonly adopted to liquidise honeys that are crystallized in the liquid state, it is frequently used to completely refill them (at 40 - 50 ° C) just before the sale is among the most adopted. The fusion can be done before or after the invasion, but the second solution is, to the effects of the results, much more effective, as it is easier to check that the fusion has been complete and the risk of re-igniting the crystallization with the manipulations of the product after the fusion. The maintenance of the liquid state, after a remelting of this type, is variable depending on the characteristics of the honey and the storage temperature. For honeys that have little glucose (water glucose ratio lower than 1.8) the duration is satisfactory. For honeys with stronger glucose content, the life time is proportionately shorter. A further recast is to be avoided, also because the large crystals that form in the heated honeys require a greater quantity of heat for the complete remelting. In terms of degradation of the product a heating at 40 ° C for a day with the purpose of melting is much less serious than a prolonged storage for months at temperatures that inhibit crystallization (above 25 ° C).
On an industrial level, more complex preparation techniques are used, which in addition to dissolving the crystals present, delay the recrystallization and can therefore also be used for honeys with an average glucose content.
First, the honeys are selected and mixed to obtain products with constant characteristics and with a not excessive glucose content. The honey is partially melted in a hot chamber, transferred to a heated tank where it is mixed and melted almost completely, then filtered and subsequently subjected to a brief heating at high temperature (pasteurization at 78 ° C for 5 - 7 minutes) with a layer heat exchanger thin. This, together with the next one, is the key step of the treatment, as the heating at high temperature, in addition to destroying the yeasts present, also dissolves the glucose microcrystals which could later re-trigger the crystallization. Before cooling, the hot honey can be filtered in a more or less "pushed" manner. Filtration that eliminates all solid microscopic particles contained in honey is prohibited in European countries, as it is believed that this removes from honey some of the substances that determine its value and because it prevents, in fact, the control of geographical origin and honey botany, feasible through the identification of the microscopic elements naturally contained in it.
The passage in a vacuum deaeration station helps to prevent the risks of recrystallization, in addition to eliminating the formation of the unsightly foam collar in the jars. Afterwards the honey is cooled to the temperature of infestation (57 ° C according to the American "school", Townsend, 1975, 35 ° C according to the European one, Gonnet, 1977), again using thin layer heat exchanger and jars, in washed or dry cleaned pots.
A further step which, according to some American authors, would contribute to prolonging life in the liquid state is constituted by a rapid cooling of the tinned product and a preservation of this for 5 weeks at 0 ° C, before being placed on the normal commercial circuit. Even with this type of treatment the results are variable, in terms of preservation in the liquid state, but more constant and prolonged. The critical step of the process is represented by the phases that follow the pasteurization: all the movements (mixing, turbulence, sliding, vibrations) or disturbances (friction in the jetting machine, air entrapment, dust of the vessels) that the liquid product undergoes tend to re-trigger crystallization.
