OA22242A - A process for obtaining a beverage (coffee) from roasted date kernels. - Google Patents

Abstract

The present invention relates to a process for obtaining a beverage (coffee) based on roasted date kernels, or similar particulate plant materials. The date kernels are roasted to develop the flavor and aroma characteristic of the product as consumed by consumers. The flavor and aroma of raw date kernels are undesirable; however, when these date kernels are roasted, complex, heat-induced chemical reactions convert the compounds contained within the kernels, such as sugars, amino acids, polysaccharides, proteins, trigonelline, chlorogenic acids, and others, into more than 800 compounds that collectively provide the desirable, extractable aroma, color, and flavor characteristic of roasted kernels. Some components of date kernels that do not react during roasting, such as caffeine, contribute to the stimulating action and flavor of roasted date kernels, but most of the flavor, color, and aroma of roasted date kernels are provided by compounds generated during roasting-induced reactions.

Description

DESCRIPTION

METHOD FOR OBTAINING A BEVERAGE (Coffee) BASED ON ROASTED DATE KERNELS.

The present invention relates to a process for obtaining a beverage (coffee) based on roasted date kernels, or with similar particulate plant materials.

BACKGROUND ART.

The date kernels are roasted to develop the characteristic flavor and aroma of the product as used by consumers.

The flavor and aroma of raw date kernels are undesirable; but when these date kernels are roasted, complex thermally induced chemical reactions convert the compounds contained in the kernels, such as sugars, amino acids, polysaccharides, proteins, trigonelline, chlorogenic acids, and others, into more than 10 of 800 compounds that collectively provide the desirable, extractable aroma, color, and flavor characteristic of roasted kernels.

Some components of date stones that do not react during roasting, such as caffeine, contribute to the stimulating action and flavor of roasted date stones, but most of the flavor, color and aroma of date stones 1 S cnnt fAiirmc γλ<»γ PAmnACPC proc ï11 tm-r Ιο ι^.ιυιινιινο sheep Axzujtino put νυιιψυοίι,ο gviivivo tuio uvo LV<4Viiwiio iiiuuilv^ p<u roasting.

The roasting of kernels involves systems of interdependent chemical reactions that proceed along series and parallel reaction pathways.

The rates of these reactions increase markedly, but to varying degrees, as the temperature of the grains increases.

Due to the interdependence of reactions and the variable effects of temperature on individual reaction rates, the composition and yield of roasting products depend on the temperature of the grains as a function of time during roasting.

Therefore, the flavor and aroma of roasted kernels depend on this history.

Controlling the temperature history over time during the 25% roasting process would greatly improve flavor and aroma control.

Roasting is initially endothermic; the heat transferred to the kernels increases their sensible heat content, evaporates water and provides heat used in endothermic reactions.

5. Once the kernel temperatures reach 160°C, rapid exothermic reactions occur, the temperature of the beans increases rapidly and the flavor of the resulting coffee changes very quickly.

Excessive weight loss and undesirable flavor changes occur if roasting is excessively prolonged.

10. Therefore, to quickly complete roasting and reliably provide coffee of the desired quality, the kernels are most often rapidly cooled (turned off) as soon as they reach a selected end-of-roasting temperature.

First, a controlled amount of water is sprayed onto the grains and largely evaporates, providing evaporative cooling.

15. Next, the cores are further cooled by forced contact with air at room temperature.

Reflectance color is the fraction of incident light of a selected spectral composition that is diffusely reflected by the surface of a suitable sample of roasted, ground, and compressed coffee.

20. The lower the reflectance color, the darker the coffee.

The final roasting temperatures are well correlated with roasting darkness, as measured by reflectance color.

The darkness of the roast, in turn, is roughly correlated with the flavor. Some consumers prefer relatively dark and bitter roasted coffees; others prefer relatively light, slightly acidic coffees; and still others prefer coffee with an intermediate character.

Roasting conditions also influence the apparent density (mass of coffee per unit volume) of roasted date kernels.

As explained in more detail below, under certain roasting conditions, date kernels can be swollen by the internal pressure of steam and other gases when the grain walls soften at high temperature; such blowing reduces the apparent density.

The apparent density of roasted kernels in turn influences the apparent density of the ground product as sold to the consumer.

T n +/37^7^^3/^+1/^71 rtAvfliiv rlnrr» rJ»-» ou kvnviuviiuii nvj-UUA HVVVÔOUV UUÜL 1111 VU11U.U1V inillUllCUA 11U1UU1CUA laULCUlS UU1 influence the taste and appearance of the product, given that the roasting activity of the kernels 35.is competitive, economic factors such as investment costs, energy costs and kernel losses during the process are of great importance.

The waste generated by the roasting process of kernels can be a source of pollution. It is important to minimize such pollution while maintaining an economical process and without compromising the quality of the finished product.

All the aforementioned factors together make roasting date kernels a complex and difficult process.

A large number of coffee roasting processes and apparatus have been proposed. Most commercial roasting processes currently in use are carried out at atmospheric pressure by bringing the kernels into contact with hot gases such as a hot inert gas, typically nitrogen.

The incoming gas heats the kernels while the outgoing gas removes waste such as the 10 balls and gases released during roasting.

Traditional roasting methods can only achieve limited rates of heat transfer to the kernels and cannot provide complete control over the history of kernel time and temperature.

In addition, traditional roasting processes and equipment require significant effort and expenditure to minimize pollution.

Various proposals have been put forward for high-pressure roasting systems. In particular, numerous patents issued to Horace L. Smith Jr. describe batch or continuous systems for pressure roasting coffee in rolling fluidized beds or spout beds.

20. A fluidized bed system directs a gas or other fluid upwards through a mass of particles such as coffee beans, so that the particles are kept suspended in the ascending fluid.

Ideally, the upward flow is nearly uniform throughout the bed. A nozzle bed system uses an upward flow of gas or other fluid concentrated at a few locations within the bed. Particles move upward at these locations and downward at other locations within the bed.

Most of Smith's patents advocate the use of pressurized, low-oxygen gas circulating in a closed loop through: a heater, a coffee roasting bed in a thick-walled cylindrical chamber, and a cyclone separator. The separator rvrlnninnp iMiminp Ipr nRtitpc nartit'iilpç enmmnnpmpnt u γκιΪΙΙρΗρο xs Hn oq?

30. Some of Smith's patents utilize gas pressures of up to 300 psig (2.1 MPa gauge). In one specific example, Robusta beans were roasted at 150 psig to enhance their flavor. The roasting gas was heated by indirect contact with either a high-temperature heat transfer fluid or hot gases produced in a fuel-fired oven.

The present invention addresses these needs. One aspect of the invention provides a beverage based on date kernels according to a roasting process for these date kernels.

Preferred methods according to this aspect of the invention include the steps of placing a load of kernels in a roasting plate having a top, a lid, and a bottom, and directing a hot inlet gas through the kernels from the adjacent bottom of said plate placed on charcoal embers to form a fluidized bed of the kernels in the plate and provide heat to the kernels, whereby an exhaust gas comprising at least a portion of the inlet gas as well as roasting by-products will be discharged from said plate placed on embers.

The methods according to this aspect of the invention most preferably include the step of trapping the kernels which are stirred at a regular rate in the plate by the gas flowing through using a sieve.

The procedures also include the following method: the operation consisting of opening a ~ t - - — - _p.~ _ - ~~ -F Γ ’ “ ' Γ ’ ........ Γ ” ’ ’ shutter near the screen so as to momentarily block the flow of gas through different sectors of the screen.

Claims (5)

1. A process for obtaining a beverage (coffee) from roasted date kernels, characterized by the following steps: a) load a load of date kernels into a roasting plate having an upper part and a lower part; b) Place this plate on embers, thus allowing hot gas to pass through the kernels. 5. circulating from the bottom of the heated plate to provide heat to the kernels, and c) trap the kernels in the heated plate, then rotate the kernels in the plate using a perforated ladle. 2. A method according to claim 1, further characterized by the step of moving a shutter above the heated plate so as to momentarily block 10. The escape of gases through the kernels, so that the kernels, kept in contact inside the heated plate and with the help of the perforated ladle, will undergo the desired roasting uniformly. 3. A process according to claim 1, further characterized in that the heating gas consists mainly of non-reactive gaseous components which are substantially non-reactive with the nuclei. 4. A process according to claim 3, further characterized in that said non-reactive gaseous components consist of nitrogen and carbon dioxide. 5. Process for obtaining a beverage (coffee) from roasted date kernels according to n’ * o ««4 yii · · 1 wx y] y*i yi yK yj ' ι χέ y*M yj rt y» 1 yl ♦'v^ rt LiiipOiLC cjucuc icvuhuilciliuh pivvcuciiic pciLiiciLia une ιυιινιανιιυη uca uv^aux uc mouicic; 20. homogeneous for a beverage (very good quality coffee) based on roasted date kernels.