641

1 INTRODUCTION

Coffea Arabica and Coffea Canephora var. Robusta

there are two main species of coffee. About 60% of the

world’s coffee production is Arabica and 40% is

Robusta. The largest Arabica coffee producers are

situated in Brazil, Colombia and Ethiopia. In turn, the

largest producers of Robusta are Viet Nam, Uganda

and India [11]. According to Goneli et al. [6], in the

world there are two main methods of processing

coffee beans: dry method and wet method. The

applied process significantly influences the selection

of appropriate the coffee beans storage and transport

conditions.

According to the data presented by the

International Coffee Organisation (ICO), global coffee

production has increased by more than 60% since the

1990s. The value of annual coffee exports during last

30 years has increased more than four times from 8.4

billion USD in 1991 to 35.6 billion USD in 2018. he

global coffee trade is characterized by two main

markets: the commodity market, which mainly offers

standard-quality bulk coffee produced in high

volumes and the specialty market, which offers higher

prices for coffee exporters handling lower volumes of

higher-quality coffee beans [11].

Coffee is one of the most popular beverages

consumed in the whole world. According to data

presented in the Coffee Development Report [11],

Europe’s coffee consumption in years 2019/20 was

estimated 55.09 million bags and has grown by an

average annual rate of about 1.3% from 38.41 million

Hygroscopic Properties of Green Coffee Transported

Sea

. Ruszkowska

, P. Dmowski

& K. Urbanowicz

Gdynia Maritime University, Gdynia, Poland

Mega Coffee, Kwidzyn, Poland

ABSTRACT: The aim of research was to evaluate the hygroscopic properties of green coffee beans determining

its quality during sea transportation. The research material consisted of seven samples of unroasted bean coffee

from different countries of origin (Kenya, India, Ethiopia, Columbia and Guatemala) obtained directly from the

coffee producer. The water content of green coffee must not exceed 12% as it then has a tendency to grow

mou

ld and become musty. Coffee beans require particular temperature, humidity/moisture and possibly

ventilation conditions and therefore, to explore and predict the behaviour during transport of green coffee its

equilibrium moisture content must be determined for a range of transport temperatures and relative humidity

levels . The present paper focuses on the evaluation of the hygroscopic properties of green coffee from different

countries of origin based on isotherms of water vapour sorption and characteristic selected parameters of the

surface microstructure determining transport conditions and the microbiological stability of this cargo. While

assessing the quality and transport durability of green coffee beans, based on the parameters of monomolecular

layer capacity and the specific surface area of sorption, it was found that especially samples of coffee from

Guatemala and Ethiopia were the least susceptible to changes in the transport conditions.

http://www.transnav.eu

the International Journal

on Marine

Navigation

and Safety of Sea Transportation

Volume 15

Number 3

September 2021

DOI: 10.12716/1001.15.03.19

642

bags in year 1990/91. The European Union (EU) is by

far the largest coffee consumer globally and accounts

for 82% of regional demand within the continent. In

2019/20, coffee consumption in the EU amounted to

45.05 million bags. Among the EU members,

Germany, France, and Italy are the three largest

consumer countries, accounting for 45% of total

consumption in whole Europe. Around 70% of the

European Union coffee imports include unprocessed

coffee imported mainly from Brazil, Viet Nam and

Honduras. More than 90% of coffee is still shipped in

green form. However, it must be stressed that, since

the beginning of 2020, the Covid-19 pandemic has

exacerbated the situation of producing countries

affected by low prices and volatility. The global

spread of the virus, in addition to its dramatic effect

on public health, has resulted in supply chain

disruptions and influenced global demand for coffee.

Coffee is transported from producer to consumer

nations in bulk or in sacks, mostly in containers

holding to 22 tonnes. During the transport even well-

dried coffee contains a great deal of water (about 12%)

that, as long as it remains evenly distributed, do not

poses the problem. However, temperature

fluctuations, that may occured during sea transport,

can cause condensation of water. And as a

consequence of re-wetting fungal and moulds may

growth [7]. Because coffee beans are sensitive to

moisture they are usually shipped in jute or sisal bags

which allows free circulation of air [2]. The net weight

of bags depend on the country of origin of coffee

beans. Coffee bags from Africa are generally 60 kg but

bags from Central America, especially from Colombia

may weigh 69 kg. Over 90% of the European coffee

imports are already transported in ventilated

containers. In sea transport, it is very important to

assign the cargo to a particular class of storage climate

conditions (SCC group). It is carried out based on the

requirements that cargo during the transport process.

In sea transport coffee like tea requires particular

temperature, humidity and ventilation conditions.

Green coffee belongs to the group of loads with the

third biotic activity, for which respiration is

essentially suspended, but biochemical and

microbiological processes are continue. Green coffee

belongs to the group of loads with the third biotic

activity, for which respiration is essentially

suspended, but biochemical and microbiological

processes are continue. Inadequate ventilation may

result in fermentation and rotting of the coffee beans.

It is the result of increased CO

2 levels and to low

supply of atmospheric oxygen [33].

Taking into consideration the required transport

conditions, coffee is classified in the SC VI group of

cargo. This group includes cargoes with a low and

medium water content from 1.5% to 30% in dry mass.

[28]. In general, temperatures during transport of

green coffee beans should range between 10 and 20°C,

because there is a connection between fluctuations in

the ambient temperature and the formation of

condensation water in the container. During the

transport from a hot climate (e.g. Brasil) to a cold

climate (e.g. Poland) the high temperature gradients

are possible and therefor. It is very important that the

temperature inside of container with coffee should not

drop below zero Celsius degrees, because a sudden

drop in temperature leads to higher probability of

condensation water formation in the container and

directly on the cargo and thus causes considerable

cargo losses. Therefor the preventing the formation of

condensation water in the hold is essential and

constitutes the number one priority during sea

transportation. Hence, the cargo in the container

should be protected from dripping water by the use of

appropriate mats. To ensure adequate ventilation, a

sufficient distance the spacing from the cargo is also

necessary. As per the sorption isotherm for green

coffee beans, with 8.5 – 10% water content are at

equilibrium with relative humidity of 50 – 65%. If

coffee beans have an excessively high moisture

content, there is a risk of mustiness, mould growth

and post or overfermentation [9, 34].

According to Baptestini et al. [1] temperature and

relative humidity of the environment surrounding the

product are the primary parameters to be considered

during transport. Due to its low moisture content,

roasted and ground coffee may absorb moisture from

the environment, causing clumping and and thus

increasing economic losses. The key metric for

assessing water sorption during transport and storage

are the sorption isotherms.

Taking into account all the above facts, it is

necessary to know the relationship between the air

temperature and relative humidity, and desirable

conditions for transport the product. To obtain this

information, sorption isotherms are indispensable,

which are efficient tools to determine thermodynamic

interactions between the water and food components.

[6].

Given these reasons the objective of this study was

to determine the adsorption isotherms of green bean

coffee. Additionally, this study sought to determine

the thermodynamic properties of water sorption as a

function of water activity (a

w).

2 RESEARCH MATERIAL AND METHODS

The research material included seven green coffee

bean samples imported to Poland by sea from India

(samples I, II and V), Ethiopia (samples III and IV)

and one sample from Columbia (VI) and Guatemala

(VII). The samples of green coffee bean were

processed in two different ways: dry method

(Ethiopia IV and India V) or natural form and wet

method (India I, II, Ethiopia III, Columbia VI and

Guatemala VII).

The tested green coffee bean samples were

subjected to a preliminary analysis by the

determination of the initial water content. Each

sample’s moisture content was determined by oven-

drying method as recommended for ISO standard ISO

6673‐2005: Green coffee – Determination of loss in

mass at 105 degrees Celsius. For water activity (a

measurement, AquaLab 4TE apparatus with an

accuracy of ± 0.003 at 20°C was used (AS4 2,14.0 2017,

Decagon Device Inc., Pullman, WA, USA).

Isotherms of adsorption were determined by the

static method, based on moisture equilibrium between

the tested product samples and the atmosphere of

defined relative humidity, adjusted by means of salt

643

solutions [5]. The determination of adsorption

isotherms was carried out at 20°C±1°C in a range of

water activity a

w=0.07÷0.98. Time fixture equilibrium

was 30 days. Based on the initial weight of the

product and the growth or loss of water content

equilibrium water content was calculated and

sorption isotherms were plotted.

For the purpose for mathematical description of

empirically determined sorption isotherms and

performance of sorption feature characterisation of

the tested green coffee bean samples, sorption

isotherms rearrangements were made by using the

BET equation (1). The water activity (aw) ranged

from 0.07 to 0.98 [22].

( )

111

V Ca

a Ca



− +−



(1)

where:

w – water activity [-],

V – adsorption [g H

2O/100g d.m.],

m – monolayer water content [g H2O/100g d.m.],

C – constant energy [kJmol

-1

The sorption properties research results were

developed using Microsoft Office Excel 365 computer

programs. The choice of the classic BET model was

determined by the recommendation of the

International Union of Pure and Applied Chemistry

(IUPAC) [32].

The fitting of empirical data to the BET equation

was characterised based on the value of determination

coefficient (r'), fitting of standard error (FitStdErr) and

statistics value F, calculated also using Jandel. Table

Curve 2D v 5.0,1 software [13].

In order to determine the suitability of the model

for the description of obtained adsorption isotherms,

analysis of the mean square error (RMS) expressed in

% was performed, which was calculated based on the

equation:

*100

zw zw

RMS

−



∑





(2)

where:

e – experimental activity, [g H2O/100g d.m.],

p – computed activity, [g H2O/100g d.m.],

N – the observation number.

Based on the water content estimated in the

monolayer adsorbed at a temperature lower than the

boiling temperature and the so called water cross‐

section”, the specific surface area of adsorbent was

calculated according to the equation (3) [22]:

(3)

where:

sp – sorption specific surface, [m

/g d.m.],

N – Avogadro number, [6.023×1023 molecules /mol],

M – water molecular weight, [18 g/mol];

ω – water setting surface, [ω = 1.05·10-

·m

/molecule].

3 RESULTS AND DISCUSSION

The determination of water content and activity are

the basic criteria for assessing the quality and

evaluation of products transported by sea. The level of

water content and activity of green coffee beans is

mostly influenced by the method of post-harvest

treatment of the grain, storage and transport

conditions. Green coffee beans, as tea leaves,

constitute very hygroscopic plant material and they

are very susceptible to water. During the green coffee

beans transportation process, the relative humidity of

the surrounding air could be increased, then beans of

coffee tend to absorb water. On the other hand, as the

relative humidity drops, green coffee beans tend to

desorb water. Very importent is also to along with

water sorption, the thermodynamic sorption

properties of the material should be monitored by

assessing the water activity (aw). According to

Baptestini et al. [1], the thermodynamic properties of

agricultural products is a key resource that can

provide information for assessing the effect of aw on

product storage and transportation and they can aid

in the understanding of the adsorbed water properties

and the study of physical phenomena that occur on

product surfaces. Table 1 presents the mean water

content and water activity of green bean coffee

samples.

Table 1. Corresponding water content and water activity

values for green bean coffee samples

_______________________________________________

Product Mean SD Water SD

water activity

content [-]

[g/100 g d.m.]

_______________________________________________

I (India) 9.8712 0.0003 0.6563 0.0015

II (India) 8.8775 0.0001 0.6218 0.0012

III (Ethiopia) 8.8795 0.0014 0.5797 0.0012

IV (Ethiopia) 8.8685 0.0003 0.5973 0.0037

V (India) 10.3785 0.0006 0.6876 0.0007

VI (Columbia) 10.6678 0.0010 0.6816 0.0003

VII (Guatemala) 8.3880 0.0007 0.5846 0.0027

_______________________________________________

Abbreviation: SD –/standard deviation

Source: Own correlation (n=3).

Table 1 indicates that the obtained values of the

initial water content of all samples of coffee was

consistent with the literature data determining the

water content in coffee and did not exceed the

recommended content of 8-12% [10, 29]. Based on the

obtained results it can be assumed that the water

content was determined primarily by the country of

origin and different processing procedures. Despite

the water content in accordance with the ICO

standards, coffee beans from India (I, II and V), as

well as coffee beans from Columbia (VI), were

characterized by a high level of water activity, which

could indicate a relatively low degree of water

bonding with the dry matrix of green coffee beans raw

[20, 21, 24].

The high values of the initial water activity in all

green coffee samples could indicate low

microbiological stability of the tested products. The

probable reason for this was the adsorption of water

on the surface of coffee beans resulting from the

phenomenon of condensation occurring as a result of

the daily temperature fluctuation during sea

transport.

644

Moisture content can be the principal parameter

for assessing the current status of a coffee lot.

Transport of coffee can be considered as an extension

of storage of coffee but at the same time introduces

practical challenges in meeting the storage strictures

of avoidance of re-wetting and maintaining the

temperature on the constant level. Even well-dried

coffee contains a great deal of water that, as long as it

remains evenly distributed, poses no problem.

However, the fluctuations of temperature can cause

condensation and local re-wetting and lead to fungal

and their metabolites - toxins (especially Ochratoxin

A) outgrowth. According to ICO, Ochratoxin A is a

heat-stable mould metabolite produced by a few

species Aspergillus especially Aspergillus ochraceus,

which which develops in environments with

temperature ranged from 8 to 37

C with the optimum

temperature between 24 and 31

C. The minimum

water activity for its development amounts to 0.76 at

C, with the optimum aw between 0.95 and 0.99.

Although Aspergillus ochraceus develops from a

water activity of 0.76 then the optimal level of aw to

the toxins produced in green coffee beans is between

0.85, and 0.97. Ochratoxin A (OTA) can occur in raw

and roasted coffee beans. Additionally the toxins

produced by these fungi survive roasting and could

present a potential hazard for health. [8, 30].

Additionally, excess water can cause the

hydrolysis of some aroma compounds, the adverse

effects of oxygen, and polymerization of the aromatic

compounds contained in coffee.

The characteristics of the green coffee beans

hygroscopic properties were determined by

comparing the position of water vapour sorption

isotherms (Fig. 1). An sorption isotherm is a graphic

representation of the relationship between water mass

per dry matter and water activity in a constant

temperature and describes the state of dynamic

equilibrium of the system. Knowledge of the shape of

isotherm allows to evaluate the mechanism

determining the water binding process in the product,

identify the product sensitivity to moisture and

predict changes during the storage of product. Results

obtained from equilibrium moisture studies are

important for knowing how a material absorbs and

loses moisture during storage, and for defining the

transport conditions in order to maintain the best

quality of product [12, 31]. Sorption isotherms are also

efficient tools to determine thermodynamic

interactions between water and food components. [6,

17, 20].

Figure 1. The sorption isotherm of water vapor product I -

VII, determined after 30 days of storage in environment

with a

w= 0.07-0.98.

Source: Own correlation.

Sorption isotherms determined empirically in the

tested green coffee beans were characterized by

sigmoidal in shape and, the classification by Brunauer

showed similarity to the isotherms of type II. These

results are similar to those found by Dmowski and

Ruszkowska [4], Menkov [15, 16] and Pałacha and

Karwowski [23], working respectively with black tea

leaves (Camellia sinensis and assamica), lentils (Lens

esculenta), chickpeas (Cicer arietinum) and bean

(Phaseolus vulgaris).

The sigmoidal shape of the sorption isotherms is

related to the occurrence of the range of monolayer

adsorption in the low water activity (aw<0.3), the

multilayer adsorption range (0.3<aw<0.75) and the

capillary condensation area (aw>0.75). Developed

sorption isotherms in the tested coffee samples,

characterized by continuity in the course of the entire

range of water activity (0.07÷0.98) with increasing

water activity increased the water content in the

analyzed green coffee beans.

Based on the analysis of the course of empirically

determined isotherms, in the range of water activity

w = 0.07÷0.55, in green coffee beans from India (II),

Ethiopia (III and IV) and Guatemala (VII), water

desorption process was found, while above the range

of environmental water activity an adsorption process

was found.

It can be assumed that such a course of desorption

and adsorption process in the tested green coffees was

determined primarily by the water content in the

tested products and its state related to the chemical

composition of products.

In wet-processed green coffee beans from India (I)

and Colombia (VI) and dry-processed coffee from

India (V), characterized by a high initial water content

and water activity (Table 1), the desorption process

involved monomolecular sorption (a

w=0.07÷0.33) and

the multilayer sorption range (a

w=0.44÷0.75) (Fig. 1).

After exceeding the water activity a

w=0.75, in all tested

samples of green coffee beans I-VII, significant

intensification of the adsorption phenomenon was

found, expressed by an increase in the rate of water

vapour absorption process, which indicated the

initiation of capillary condensation. This phenomenon

can be equated with exceeding the level of critical

moisture, which determines the loss of product's

ability to be stored further [20].

By comparing the course of sorption curves in a

common frame of reference it was found that coffee

beans from India II (wet method production) had a

higher position, indicating greater hygroscopicity

(starting from water activity a

w=0.85). According to

the literature data, the course of sorption isotherms

could probably be affected by the diverse chemical

composition of the I–VI products, but above all by

their structure (Fig. 1). When assessing the sorptive

properties of lyophilized strawberries, Ciurzyńska

and Lenart [3], found that they have a sigmoidal

shape characteristic of most food products,

corresponding to type II isotherms. In turn, Moraga,

Martinez-Navarrete and Chiralt [18] for freeze-dried

strawberries obtained a sorption isotherm course

typical of products with high sugar content. Probably,

it is connected with the slow changes in equilibrium

645

water contents at low water activity and rapid

increase of water activity above 0.5.

In order to determine the selected parameters of

surface microstructure, the empirical data was

subjected to the use of the Brunauer, Emmett and

Teller equation BET (1). The course of sorption

isotherms in the water activity range from 0.07 to 0.33

enabled to determine the parameters of BET equation

(vm, ce) by assaying the degree of its fit (R2, RMS,

SKO) to empirical data. The results were presented in

Table 3.

According to the literature data, the mean square

error (RMS) is lower than 10% and this indicates a

good agreement of the model fit to the data in the

studied range of water activity [20, 23]. Based on the

research, it was found that the calculated RMS in

green coffee beans I-VI ranged from 3.66% to 9.04%.

This confirmed that the parameters of the BET model

mathematically properly describe the process of water

vapor sorption on the surface of evaluated green

coffee beans. Only in the case of green coffee beans

from Guatemala (VII), the RMS value exceeded 10% -

indicating a smaller fit of the model.

Monolayer capacity (vm) determined based on the

BET equation, corresponds to a single layer of

molecules adsorbed water vapour and is referred to as

an indicator of the availability of polar water vapour

independently, the component of which is a source of

hydrophilic groups [14]. Theoretically, the water

content of the layer corresponds with the optimum

amount of water in the product and indicates the

quality of the storage and transport stability. The

monolayer moisture content is the safest moisture

content for storage and transport purposes, because at

a certain temperature it provides the increased time

period with minimum quality loss. Values below

monolayer moisture content slow down the

respiration rate of the product and the action of pests

[6]. On the other hand, the excess of water in relation

to the monomolecular layer leads to achieving the

critical humidity, the excess level of which may cause

undesirable changes in the product, especially the

development of microorganisms and toxins produced

by fungi (OTA), that are very dangerous. [8, 14, 19,

26].

The determined values of monolayer v

m range

from 3.06 g H

2O/100g for coffee originated from India

to 4.77 g H

2O/100g for coffee from Guatemala (Table

3). The obtained results showed that a greater surface

area of sorption was characterized by the Guatemalan

coffee processed by wet method, thus coffee from this

region was characterized by the highest storage and

transport stability.

According to Babtestini et al. [1] the C constant is

associated with the chemical potential differences

between the monolayer and superior layers. Constant

energy gives information about the difference

between the enthalpy of desorption monolayer and

the enthalpy of vaporization of the liquid adsorbent.

The results of constant Ce (Ce ≥ 2) confirm the

sigmoidal shape of the curve of adsorption and

suggest that in the tested products only a process of

physical adsorption was observed [27]. The lowest

value of constant Ce was characteristic of the coffee

from Guatemala, which indicated a lower amount of

heat released from the product in the sorption

process.

The determined values of monolayer capacity (vm)

based on the BET model constituted grounds for the

calculation of the sorption specific surface (Table 1).

The highest value of monolayer capacity based on the

BET model was determined in coffee from Guatemala

(VII) ‐ 167.7468 m

/g, and the smallest in coffee

from India (II) ‐ 107.6927 m

/g. Thus, it is possible

to assume that the highest stability and storage

stability determined by the value of monomolecular

layer, was characteristic of the samples from

Guatemala (VII). Based on the obtained results, it can

be assumed that the differences in the microstructure

of the product surface were determined by the

different treatment process parameters used by the

producers of the tested products and a different raw

material composition of the tested green coffee beans.

It can also be assumed that the process of

technological processing as well as the process of

transporting products by sea caused changes in the

structure of the evaluated green coffee beans.

Probably the products imported from India (I, II, V),

Ethiopia (III, IV) and Colombia (VI) were

characterized by a smaller number of active sites

capable of attaching water molecules. According to

Ocieczek [21] and Ruszkowska [25] the size of

sorption specific surface is the product of total surface

area and its affinity for water molecules determined

by the distribution of functional groups.

The research also included the measurement of

water activity of green coffee beans, performed after

30 days of storage in hygrostats with constant relative

humidity covering the range of water activity between

0.07 and 0.98 (Fig 2.).

Table 3. BET equation parameters and specific surface of sorption [m

/g]

__________________________________________________________________________________________________

Product vm [gH2O/100g] ce R

RMS [%] SKO Specific surface of sorption [m

/g]

__________________________________________________________________________________________________

I (Indie) 3.6806 8.7084 0.9944 8,5062 1,1668 129.3134

II (Indie) 3.0652 27.0375 0.8110 3,6630 1,3673 107.6927

III (Ethiopia) 3.9922 9.5233 1.0000 9,0408 1,4655 140.2632

IV (Ethiopia) 3.6904 11.5388 0.9971 4,7529 0,8982 129.6601

V (Indie) 3.5597 10.7666 0.9973 5,7973 1,0111 125.0669

VI (Columbia) 3.5918 11.6868 0.9974 8,5602 1,2313 126.1958

VII (Guatemala) 4.7745 4.7595 0.8778 28.5784 1,9110 167.7468

__________________________________________________________________________________________________

Abbreviation: R

- determination coefficient; FitStdErr - standard error; SKO – sum of squared deviations

Source: Own correlation.

646

Figure 2. Water activity of I - VII green coffee, determined

after 30 days of storage in the range of a

w from 0.07 to 0.98,

at 20°C.

Source: Own correlation.

Fig. 2 provides that the greatest differences

between environmental water activity and water

activity measured in green coffee beans were

observed in the environment with water activity

w=0.75÷0.98). Adsorption processes dominated in

this range of water activity. It was found that the time

of storage and possible transport of raw materials

were too short for the investigated raw materials to

reach a state of equilibrium in higher environmental

water activities.

Evaluation of the analyzed parameters is of

fundamental importance to the correct transportation

of the product, providing necessary information to

design the climatic conditions such as temperature or

relative humidity.

4 CONCLUSIONS

1 1. Under the obtained results, it can be concluded

that the examined green coffees, despite having a

similar initial water content in line with the Code

of Practice guidelines, were characterized by a

high level of initial water activity.

2 2. High water activity in the green coffee beans

imported to Poland by sea from India (I, II and V),

as well as coffee from Colombia, may indicate the

process of mouldy grains and thus contribute to

the formation of Ochratoxin A (OTA).

3 3. Assessing the quality and transport durability of

green coffee beans, based on the parameters of the

monomolecular layer capacity and the specific

surface area of sorption, it was found that coffee

imported from India (II) was the least susceptible

to changes in the transport conditions.

4 4. Taking into consideration the quality, storage

and transport stability of the tested green coffee

beans, the coffees processed by wet method,

imported from Guatemala (VII) and Ethiopia (III)

have had the best sorption properties. These were

the samples with the highest monomolecular layer

capacity.

REFERENCES

1. Baptestini, F.M., Corrêa, P.C., Oliveira, G.H.H. de,

Cecon, P.R., Soares, N. de F.F.: Kinetic modeling of

water sorption by roasted and ground coffee. Acta

Scientiarum. Agronomy. 39, 273–281 (2017).

2. CargoHandbook: Coffee Beans,

https://cargohandbook.com/Coffee_Beans, last accessed

2021/04/25.

3. Ciurzyńska, A., Lenart, A.: The influence of temperature

on rehydration and sorption properties of freeze-dried

strawberries. Croatian journal of food science and

technology. 1, 1, 15–23 (2009).

4. Dmowski, P., Ruszkowska, M.: Equilibrium Moisture

Content Importance in Safe Maritime Transport of Black

Tea. TransNav, the International Journal on Marine

Navigation and Safety of Sea Transportation. 12, 2, 399–

404 (2018). https://doi.org/10.12716/1001.12.02.22.

5. Gondek, E., Jakubczyk, E., Jazdzyk, B.: Wpływ dodatku

błonnika na właściwości sorpcyjne owocowych nadzień

cukierniczych. Zeszyty Problemowe Postępów Nauk

Rolniczych. 573, (2013).

6. Goneli, A.L.D., Corrêa, P.C., Oliveira, G.H.H., Afonso

Júnior, P.C.: Water sorption properties of coffee fruits,

pulped and green coffee. LWT - Food Science and

Technology. 50, 2, 386–391 (2013).

https://doi.org/10.1016/j.lwt.2012.09.006.

7. Guidelines for the Prevention of Mould Formation in

Coffee: FAO, http://www.fao.org/3/au628e/au628e.pdf,

last accessed 2021/04/24.

8. Guidelines for the Prevention of Mould Formation in

Coffee: ICO,

http://www.ico.org/documents/ed1988e.pdf, last

accessed 2021/04/24.

9. How to Protect Coffee Quality During Sea Transit:

https://perfectdailygrind.com/2020/04/how-to-protect-

coffee-quality-during-sea-transit/, last accessed

2021/04/24.

10. International Coffee Organization: Code of Practice.

Enhancement of coffee quality through prevention of

mould formation,

http://www.ico.org/documents/pscb36.pdf, last accessed

2021/04/04.

11. International Coffee Organization: Coffee development

Report. The value of coffee. Sustainability, Inclusiveness,

and Resilience of the Coffee Global Value Chain,

https://www.internationalcoffeecouncil.com/cdr2020,

last accessed 2021/04/04.

12. Kedzierska, K., Palacha, Z.: Wpływ temperatury na

właściwości sorpcyjne suszu pieczarek. Acta

Agrophysica. 17, 1(188), 77–88 (2011).

13. Lewicki, P.: A Three Parameter Equation for Food

Moisture Sorption Isotherms. Journal of Food Process

Engineering. 21, 2, 127–144 (1998).

https://doi.org/10.1111/j.1745-4530.1998.tb00444.x.

14. Mathlouthi, M.: Water content, water activity, water

structure and the stability of foodstuffs. Food Control.

12, 7, 409–417 (2001). https://doi.org/10.1016/S0956-

7135(01)00032-9.

15. Menkov, N.D.: Moisture sorption isotherms of chickpea

seeds at several temperatures. Journal of Food

Engineering. 45, 4, 189–194 (2000).

https://doi.org/10.1016/S0260-8774(00)00052-2.

16. Menkov, N.D.: Moisture sorption isotherms of lentil

seeds at several temperatures. Journal of Food

Engineering. 44, 4, 205–211 (2000).

https://doi.org/10.1016/S0260-8774(00)00028-5.

17. Mieszkowska, A., Marzec, A.: Właściwości sorpcyjne

ciastek kruchych z mąką z ciecierzycy. Zeszyty

Problemowe Postępów Nauk Rolniczych. 582, 35–42

(2015).

18. Moraga, G., Martınez-Navarrete, N., Chiralt, A.: Water

sorption isotherms and glass transition in strawberries:

influence of pretreatment. Journal of Food Engineering.

62, 4, 315–321 (2004). https://doi.org/10.1016/S0260-

8774(03)00245-0.

19. Ocieczek, A., Kłopotek, K.: Badania nad

higroskopijnością kaw instantyzowanych w aspekcie ich

647

trwałości przechowalniczej. Problemy Higieny i

Epidemiologii. 94, 4, 879–882 (2013).

20. Ocieczek, A., Ruszkowska, M.: Porównanie właściwości

sorpcyjnych ziarna wybranych odmian komosy ryżowej

(Chenopodium quinoa Willd.). Żywność: nauka -

technologia - jakość. 25, 3(116), 71–88 (2018).

21. Ocieczek, A., Ruszkowska, M., Palich, P.: Porównanie

właściwości sorpcyjnych wybranych rodzajów skrobi.

Bromatologia i Chemia Toksykologiczna. 45, 3, 1018–

1023 (2012).

22. Paderewski, M.: Procesy adsorpcyjne w inżynierii

chemicznej. WNT, Warszawa (1999).

23. Pałacha, Z., Karwowski, W.: Badanie stanu wody w

nasionach wybranych roślin strączkowych metodą

wykorzystującą izotermy sorpcji. Zeszyty Problemowe

Postępów Nauk Rolniczych. 594, 49–58 (2018).

24. Rahman, M.S.: State diagram of foods: Its potential use

in food processing and product stability. Trends in Food

Science & Technology. 17, 3, 129–141 (2006).

https://doi.org/10.1016/j.tifs.2005.09.009.

25. Ruszkowska, M.: Jakość ekstrudatów kukurydzianych

wzbogacanych spiruliną i chlorellą. Wydawnictwo

UMG w Gdyni, Gdynia (2018).

26. Ruszkowska, M., Dmowski, P.: The Evaluation Quality

of Black Tea - Based on the Characteristics of

Hygroscopic Properties Designated by the Static

Method. Towaroznawcze Problemy Jakości. 4, 61–71

(2017).

27. Ruszkowska, M., Kropisz, P., Wiśniewska, Z.:

Evaluation of the stability of the storage of selected fruit

and vegetables freeze-dried powder based on the

characteristics of the sorption properties. Scientific

Journal of Gdynia Maritime University. 109, 55–63

(2019). https://www.doi.org/10.26408/109.05.

28. Sharnow, R.: Ładunkoznawstwo okrętowe. Wyd. WSM

w Gdyni, Gdynia (200)AD.

29. Smiechowska, M., Dmowski, P., Przybylowski, P.:

Ocena jakosci kawy zielonej importowanej do Polski.

Żywność Nauka Technologia Jakość. 10, 3, 101–109

(2003).

30. Specialty Coffee Association of America: Water Activity

for Green Coffee,

http://www.scaa.org/?page=resources&d=water-activity,

last accessed 2021/04/12.

31. Temple, S.J., van Boxtel, A.J.B.: Equilibrium Moisture

Content of Tea. Journal of Agricultural Engineering

Research. 74, 1, 83–89 (1999).

https://doi.org/10.1006/jaer.1999.0439.

32. Timmermann, E.O.: Multilayer sorption parameters:

BET or GAB values? Colloids and Surfaces A:

Physicochemical and Engineering Aspects. 220, 1, 235–

260 (2003). https://doi.org/10.1016/S0927-7757(03)00059-

33. Transport Information Service: Coffee, https://www.tis-

gdv.de/tis_e/ware/genuss/kaffee/kaffee-htm/, last

accessed 2021/04/26.

34. Ładunki okrętowe - poradnik encyklopedyczny. Polskie

Towarzystwo Towaroznawcze - Oddział Morski, Sopot

(1994).