Food or edible material: processes – compositions – and products – Processes – Separating a starting material into plural different...
Patent
1989-02-28
1990-12-04
Czaja, Donald E.
Food or edible material: processes, compositions, and products
Processes
Separating a starting material into plural different...
4263005, 426422, 210615, 210798, A23L 230
Patent
active
049752979
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for aftertreatment of at least partially clarified liquids, in particular clarified juices of fruits, berries or vegetables, in each case with an agent to prevent subsequent clouding and/or for color lightening, and the juice is brought into contact with the agent and the agent is retained by a filter.
In some cases, a subsequent clouding of the juice occurs after clarifying juice, especially during clarification by ultra-or micro-filtration, after a certain storage time and under certain conditions, for example after concentration. To prevent this, in practice the treatment of the juice with an agent, the so-called PVPP (polyvinylpolypyrrolidone), which is able to bond selectively the polyphenols that cause subsequent clouding, has proven itself very reliable. PVPP is a fine powder that is added at a concentration of, for example, 10-100 gr/HL to the juice to be aftertreated and, after a retention time of, e.g., about 5 minutes, is again filtered out of the juice, which afterwards is clouding-stable. Since PVPP is relatively expensive, units are mainly used in which the PVPP can be recovered. The same treatment is also used if a lightening of the juice is desired.
A known process for aftertreatment of clarified juice consists in that to the clarified juice that is delivered from an ultra-, micro- or conventional filtering unit there is added the agent PVPP and the mixture of clarified juice and PVPP flows through a precoated filter. With the aid of a dosing device, the PVPP concentration in the juice is adjusted. Inside the precoated filter, the suspended PVPP is retained by the filter surfaces, so that the exiting juice is free of PVPP. Another filtration of the juice occurs by another filter which, for safety reasons, is connected downstream from the precoated filter and ensures that no more PVPP is contained in the juice. As time goes by the filter cake consisting of PVPP keeps on getting thicker on the precoated filter. The throughput becomes correspondingly smaller until the unit must be shut off. After shutting off the juice feed, so-called wash water and lye flow through the deposited PVPP or the filter cake. The relatively expensive PVPP is regenerated by the lye and, by dissolving the filter cake and bringing it into the dosing device, it can be used again.
The suspended form of pulverulent agents such as, e.g., PVPP, activated carbon or fining agents such as bentonite, etc., in the juice, offer ideal conditions for a good mass transfer between juice and agent to remove undesired matter from the juice, for example by adsorption on the agent, as well as for the operation of the process.
But the known process of precoated filtration has the drawback that the suspended agent is deposited relatively quickly on the filter surfaces by the static filtration and a precoat layer forms. The result of this is a lesser effectiveness of the PVPP, which is now present in the form of a so-called fixed bed that is relatively thin and is quickly flowed through. The matter responsible for clouding the juice is thus often not broken down sufficiently with the concentrations for, e.g., PVPP to some extent allowed by law. Further, the growing filter layer causes a correspondingly increasing reduction of the throughput. Another drawback consists in the fact that only agents can be used which, because of their structure, generate a relatively well permeable filter precoating and thus guarantee an economical throughput. This is achieved with a special PVPP agent, but which is considerably more expensive than the normal PVPP that is already expensive in itself. This also causes increased operating costs, since the loss of agent during regeneration is about 1-2%. Further, it is a drawback that the process must be interrupted independently of the throughput as soon as the filter layer has reached a certain size, which is given by the distances between the filter elements. The higher the concentration of the suspension, the faster this state is reached. Further, the PVPP regeneration requi
REFERENCES:
patent: 2423172 (1947-06-01), Booth
patent: 4631193 (1986-12-01), Sobus
patent: 4724080 (1988-02-01), Dau et al.
patent: 4746441 (1988-05-01), Yagishita et al.
Bucher-Guyer AG Maschinenfabrik
Czaja Donald E.
Jaskiewica Edmund M.
Pratt Helen
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