Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-07-21
2001-06-05
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C374S149000, C099S467000
Reexamination Certificate
active
06242714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a noncontact article temperature measuring device for food based on capacity measurement of food article such as frozen hamburger, frozen meatball, and processed food, for enabling the production of homogeneous and high quality processed food and frozen food, specifically to a noncontact article temperature measuring device used for a freezing/thawing system in which the evaluation of qualities including article temperature, frozen/thawed state of food, presence/absence of bubble in food, and also the evaluation/control of operation of a thawing device are possible according to the measurement data.
Here, the article temperature of food includes quality evaluation such as the temperature, frozen/thawed state of food, and presence/absence of bubble in food.
BACKGROUND ART
Food, when frozen, can be preserved over a prolonged period by retarded biochemical reaction along with suppressed action of microorganism under decreased activity of water in the food owing to low temperature and freezing of the water contained in the food. The limit temperature for multiplication of microbe is about −10° C., and that of yeast is about −18° C.
It is said, therefore, that food is unlikely to be rotten or decomposed by self digestion when refrigerated under −18° C. (deep frozen state).
According to the Japanese Agricultural Standard, freezing method of processed food article such as hamburger and meatball should be such that the food article are rapidly passed through a temperature range from −1° C. to −5° C. which is the maximum ice-crystal formative temperature range in which most part of the water in the food freezes, to be frozen to −18° C.
Water contained in food comprises free water which can move freely and easy to be frozen and bound water which is hard to be frozen. The latter is the water in hydrated molecule of protein, glycogen, etc. and the higher the degree of hydration is, the harder it is to be frozen. So it is the free water in food that forms ice-crystal when the food is frozen. When food is cooled to freezing point, ice separates as crystal in the water solution in the food. When the food is further cooled below freezing point to the maximum ice-crystal formative temperature range (temperature range from −1° C. to −6° C. in the case freezing point of the food is −1° C.), ice-crystal grows in this temperature range, which causes the destruction of cell membrane. Therefore, it is desired that minute ice-crystals are separated by quick freezing in which the food is cooled passing through the maximum ice-crystal formative temperature range in short time so as to restrain the physical destruction of cells to the minimum.
It is also said that frost damage does not occur in the case where freezing is performed in a way in which, as even in the case of the said quick freezing a lot of small ice-crystals are formed in and outside of a cell and destruct the cell, this phenomenon is prevented by restraining initial freezing speed to a degree the separation of ice-crystal in the cell does not occur and shifting to quick freezing after the outside of the cell is solidified with ice-crystals.
For the operation without frost damage like this, it is necessary to know accurately an ever-changing temperature of food during freezing and to control freezing through programmed control responding to the change of the temperature.
Also, the uniformization of uneven temperature in a food article from the surface to deep part caused by quick freezing is necessary to be performed by interposing a temperature uniformizing freezing process between the said quick freezing and deep freezing (freezing to a temperature under the maximum ice-crystal formative temperature, for example, to a neighborhood of −20° C.), which temperature uniformizing freezing is possible by the change of freezing medium and freezing condition.
In this case also accurate understanding of food temperature and programmed control of freezing based on the understood measured food temperature is necessary.
It is said that, particularly in the freezing process of a cooked food article, the physical damage of fleshy or pulpy substance should be minimized by obtaining finer ice-crystal in quick freezing to minimize the physical and chemical influences to the composition of the food and then storage in low temperatures under −18° C. with small deviation of ±2° C. is necessary lest the growth of ice-crystal does not proceed fast during the storage.
In an individual freezing in which small sized food articles are individually frozen, it is necessary to measure the surface, center, and balanced temperature of each food article, to draw up their freezing curves, to freeze under an appropriate condition of freezing environment temperature, freezing speed, etc., and to check food temperature after freezing.
In unfreezing of food, rapid passing through the maximum ice-crystal thawing zone by rapid unfreezing is required, in the point of view of biochemical and enzymatic reaction, to keep the food temperature under −10° C., possibly under −5° C., until the food temperature is raised to 0° C. That is, also in this case, an unfreezing with high temperature at initial stage and then a programmed unfreezing with low temperature is required.
It is important to efficiently produce with low mortality homogeneous and high quality frozen food articles, that various states of the food such as temperature, temperature decreasing speed, freezing speed, completion of freezing, shape, size, composition, and in the case of continuous cooling/freezing/heating apparatus, arrangement on the transfer belt and transfer speed, are grasped and the most suitable and efficient operation for freezing the food is performed.
By the way, hitherto, the measurement of the temperature of a food article in freezing or unfreezing process has been performed by measuring the temperature of the surrounding air, water, or brine which comes in contact with the food article, or of the surface of the food article by allowing a sensor to contact the same, or of the inside of the food article by thrusting a sensor into the same and thus the temperature of a food article has not been grasped as the whole.
In the case of measurement by thrusting a sensor, the measured food article can not be used as a product, and in the case of measurement by contacting a sensor it is unhygienic.
Further, according to the conventional method, measurement of temperatures at various parts of a number of food articles have been practically impossible and so measurement has been performed on selected parts of a small number of sampled food articles and inferences have been made from the freezing environment such as the temperature, speed, direction of the cooling air, and freezing period. The control of the operation of a freezing apparatus has been done through feedback of the data of the freezing environment not that of the data of the temperature and degree of freeze of the food articles.
In the mean time, from now, to respond to the demands from user side such as PL Act, HACCP (Hazard Analysis and Critical Control Point), cost down, and differentiation of product with high added values, the quality control and operation control with high accuracy will be indispensable. However, by conventional method, a variety of sensors and measurement devices such as; for example, contact and/or insert temperature sensor; radiation surface thermometer; chemical and physical analyzer of sampled piece of food; X-ray or radiologic, magnetic, supersonic, photoelectronic devices; image sensor; touch sensor; have been used in accordance with increasing measurement items, and there have occurred problems such as the complication of apparatus and its operation, increase in the number of samples, and increase of work for caring sensors.
The most crucial point is the problem of hygienic quality of food article due to contacting of sensors with the food article.
For example, when measuring t
Hagura Yoshio
Kato Eiji
Maeda Tomoko
Narumiya Tadaoki
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Mayekawa Mfg. Co., Ltd.
Robinson Daniel
Walberg Teresa
LandOfFree
Noncontact article temperature measuring device for food does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Noncontact article temperature measuring device for food, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Noncontact article temperature measuring device for food will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2489564