Instruments to which this note applies:  Biocal 2000, Biocal 4000 

 
Prepared by: Lars Wadsö 
 
Target use: Research, Development and Innovation in Food Science and other Life Sciences. Process Control in Food processing and  technology.

Introduction

등온열량측정법은 신선한 채소, 발효 중인 제품 또는 미생물 활동에 의한 부패가 일어나는 식품과 같이 살아있는 물질들의 공정의 결과를 내는데에 가장 효과적인 방법입니다. 이 Application Note에는 등온 열량 측정법이 식품의 유통기한에 대한 연구를 위해 사용된 과학 문헌들이 포함되어있습니다. 이것은 대략적은 목록이지만 열량 측정법으로 만들어진 식품 생물학에 대한 훨씬 더 많은 연구가 있습니다.

“등온열량측정법” 이라는 단어는 일정한 온도에서의 화력과 열을 측정하는데 사용됩니다. 이 측정법의 다른 용어는 “미세열량측정법”(µW수준에서 측정가능하지만 반드시 등온 조건은 아님), 열전도 열량측정법(어떻게 이 장비가 작동되는지 알려줌) 그리고 항온 환경 열량측정법(다소 혼동되는 단어)이 있습니다.

등온열량측정법는 대부분의 경우 온도 변화로 인한 열 발생을 모니터링하는 것보다 일반적인 열시차 열량 분석법 (DSC)과 뚜렷이 다릅니다. 등온열량게는 이 문헌 검토에서 논의 된 생물학적 과정과 같이 일정한 온도에서 일어나는 과정을 연구하는데 사용됩니다. 그들은 일반적으로 더 나은 온동 안정성을 가지며 훨씬 더 큰 샘플에 적합하며 등온 모드에서 실행되는 DSC기기보다 훨씬 더 높은 감도를 갖습니다. 등온열량측정법 및 DSC는 식품실험실에서 상호보완적인 기술입니다. 이것은 주로 비생물학적 식품 열량 측정법의 예시로 사용되는 논물들입니다:

• Le Parlouër, P. and L. Benoist, Methods and applications  of microcalorimetry in food, in Calorimetry in food  processing, G. Kaletunc, Editor 2009, Wiley-Blackwell: Ames, Iowa, USA. p. 15-49.
• Gaisford, S., M. O'Neill, and A. Beezer, Shelf life prediction  of complex food systems by quantitative interpretation if  isothermal calorimetric data, in Calorimetry in food  processing, G. Kaletunc, Editor 2009, Wiley-Blackwell: Ames, Iowa, USA. p. 237-263.

General references

• Wadsö, L. and F. Gómez Galindo, Isothermal calorimetry  for biological applications in food science and technology. Food Control, 20 (2009) 956-961.

This  paper  discusses  isothermal  calorimetry  and  gives  examples  of  its  use  to  study  vegetable  respiration,  fermentation and shelf life issues.

Respiration

•  Gómez,  F.,  et  al.,  Isothermal  calorimetry  approach  to  evaluate  tissue  damage  in  carrot  slices  upon  thermal  processing. J. Food Eng., 65 (2004) 165-173.

• Gómez  Galindo,  F.,  et  al.,  The  potential  of  isothermal  calorimetry in monitoring and predicting quality changes  during  processing  and  storage  of  minimally  processes  fruits  and  vegetables.  Trends  Food  Sci.  Technol.,  16 (2005) 325-331.

• Gómez  Galindo,  F.,  R.  Toledo,  and  I.  Sjöholm,  Tissue  damage in heated carrot slices. Comparing mild hot water  blanching and infrared heating. J. Food Eng., 67 (2005).

• Gómez Galindo, F., et al., Exploring metabolic responses of  potato tissue induced by electric pulses. Food Biophysics, 3 (2008) 352-360.

• Peredes Escobar, M., et al., Effect of long-term storage and  blanching  pre-treatments  on  the  osmotic  dehydration  kinetics  of  carrots  (Daucus  carota  L.  cv.  Nerac).  J.  Food Eng., 81 (2007) 313-317.

•  Rocculi,  P.,  et  al.,  The  potential  role  of  isothermal  calorimetry  in  studies  of  the  stability  of  fresh-cut  fruits. LWT - Food Sci. Technol., 49 (2012) 320-323.

•  Rocculi,  P.,  et  al.,  Effects  of  the  application  of  anti- browning substances on the metabolic activity and sugar  composition  of  fresh-cut  potatoes.  Postharvest  Biol. Technol., 43 (2007) 151-157.

•  Panarese,  V.,  et  al.,  Isothermal  and  differential  scanning  calorimetries  to  evaluate  structural  and  metabolic  alterations of osmo-dehydrated kiwifruit as a function of  ripening  stage.  Innovative  Food  Sci.  Emerging  Technol., 15 (2012) 66-71.

• Gómez, Wadsö and co-workers have made several studies in  which  they  use  isothermal  calorimetry  to  quantify  activity  changes  in  vegetables  being  exposed  to  different  unit  operations  in  the  food  industry.  Generally,  the  aim  of  these  studies has been to find indications of conditions that would  cause  minimal  damage  to  the  tissue  and  thus  a  processed  product that keeps as much of its original texture, flavor etc.  as possible.

•  Tortoe, C., et al., Potential of calorimetry to study osmotic dehydration of food materials. J. Food Eng., 78 (2007).

This paper shows that isothermal calorimetry can be used to  divide  the  osmotic  dehydration  of  fruits  or  vegetable  into  different  parts;  however,  the  authors  do  not  interpret  the  observed  thermal  power  regimes  in  terms  of  biologically  produced heat, but only discuss it in physical terms.

Fermentation and yeast studies

• Dubrunfaut,  M.,  Note  sur  la  chaleur  at  le  travail  méchanique  produits  par  la  fermentation  vineuse.  C.  R. Hebdomadaires Seances Acad., 42 (1856) 945-948.

This  is  the  first  study  of  the  heat  production  from  a  fermentation process, but it was not made in a calorimeter;  instead  the  heat  balance  of  a  whole  fermentation  vat  was  assessed.

• Calvet, E. and H. Prat, Recent progress in  microcalorimetry (1963) Oxford: Pergamon Press.

An  example  of  the  result  from  a  one  day  study  of  beer  fermentation is given in this interesting book with examples  of microcalorimetric measurements in many fields.

• Riva,  M.,  et  al.,  Growth  and  fermentation  activity  of  Streptococcus* thermophilus  and  Lactobacillus* bulgaricus  in  milk:  a  calorimetric  investigation.  Annali  di  Microbiologia ed Enzimologia, 47 (1997) 199-211 (paper  is in English).

The  cultures  were  injected  into  the  milk  and  a  pH-meter  placed  in  the  vial  enabled  simultaneous  determinations  of  thermal power and pH. The study confirmed the cooperative action of a mixed yogurt culture.

• Riva,  M.,  et  al.,  Calorimetric  characterization  of  different  yeast strains in doughs. J Thermal Anal, 52 (1998) 753-764.

The  growth  of  three  yeast  strains  in  a  dough  system  was  investigated by calorimetry and other methods, for example  image  analysis,  to  determine  the  volume  expansion.

Significant differences were found between the three strains.

•  Schäffer,  B.,  et  al.,  Examinatio  of  growth  of  probiotic  microbes  by  isoperibolic  calorimetry.  J.  Thermal  Anal. Calorim., 102 (2010) 9-12.

• Schäffer,  B.,  S.  Szakály,  and  D.  Lorinczy,  Examination  of  the  growth  of  probiotic  culture  combinations  by  the  isoperibolic  batch  calorimetry.  Thermochim  Acta,  415 (2004) 123-126.

Two papers that show calorimetric thermal power curves for  different probiotic bacterial cultures in milk.

• Seratlić, S., et al., Behavior of the surviving population of  Lactobacillus  plantarum  564  upon  the  application  of  pulsed  electric  fields.  .  Innovative  Food  Sci.  Emerging Technol., 17 (2013) 93-98.

This study shows that, although a pulsed electric field (PEF)  treatment  inactivates  the  majority  of  the  bacteria,  the  remaining bacterial population showed higher resistance to  further PEF treatment

• Kabanova,  N.,  I.  Stulova,  and  R.  Vilu,  Microcalorimetric  study  of  growth  of  Lactococcus  lactis  IL1403  at  low  glucose  concentration  in  liquids  and  solid  agar  gels. Thermochim. Acta, 559 (2013) 69-75.

Calorimetric measurements of microbial growth at different  glucose  concentrations  and  different  inoculation  densities made it possible to construct a multistage growth model.

• Kabanova,  N.,  I.  Stulova,  and  R.  Vilu,  Microcalorimetric  study of the growth of bacterial colonies of Lactococcus  lactis IL1403 in agar gels. Food Microbiol., 29 (2012) 67- 79.

An interesting study where the difference  in colony  morphology and colony size is seen both in calorimetric and  microscopy results.

• Kazarjan, A., N. Kabanova, and R. Vilu, Microcalorimetric  study of extruded dog food containing probiotic  organisms. Adv. Microbiol., 2 (2012) 436-440.

Isothermal calorimetry is shown to be a method to check the  activity  of  probiotic  organisms  under  low  pH  (stomach  conditions) in a dried foodstuff.

• Stulova,  I.,  et  al.,  Fermentation  of  reconstituted  milk  by  Streptococcus thermophilus: Effect of irradiation on skim milk powder. Int. Dairy J., 31 (2013) 139-149.

Isothermal  calorimetry  is  well  suited  to  assess  differences  between  the  growth  kinetics  of  different  systems;  here  between  two  different  substrates:  reconstituted  milk  from  irradiated and non-irradiated skim milk powder.

Shelf life, predictive microbiology and spoilage  

• Sacks, L.E. and E. Menefee, Thermal detection of spoilage  in canned foods. J Food Sci, 37 (1972) 928-931.

The first mentioning of the possibility of detecting microbial  activity  (and  possibly  also  other  types  of  processes)  with  calorimetry in sealed packages without opening them. In this  case  the  temperature  increase  of  the  canned  food  was  monitored.

•  Lampi,  R.A.,  et  al.,  Radiometry  and  microcalorimetry - techniques  for  the  rapid  detection  of  foodborne  micro-organisms. Food Technology, (1974) 52-58.

The  authors  show  that  it  is  possible  to  detect  microbial  growth  in  soy  broth  after  only  a  few  hours.  Higher  inoculation levels gave shorter detection time.

•  Gram,  L.  and  H.  Sögaard,  Microcalorimetry  as  a  rapid  method for estimation of bacterial levels in ground meat.  J. Food Protect., 48 (1985) 341-345.

A  fundamental  study  in  which  ground  meat  was  inoculated  with  different  concentrations  of  bacteria.  The  resulting  thermal  power  profiles  corresponded  well  with  the  inoculation densities.

• Nunomura,  K.,  K.  Ki-Sook,  and  T.  Fujita,  Calorimetric  studies of microbial activities in relation to water content of food. J. Gen. Appl. Microbiol., 32 (1986) 361-365.

The  authors  used  isothermal  calorimetry  to  show  that  the  growth  of  both  a  mold  fungus  and  a  bacterium  were  dependent on the water content of skim milk powder.

• Iversen, E., E. Wilhelmsen, and R.S. Criddle, Calorimetric  examination  of  cut  fresh  pineapple  metabolism.  J.  Food Sci., 54 (1989) 1246-1249.

Isothermal  calorimetry  was  found  to  be  a  good  method  to  detect  microbial  activity  in  cut  pineapple.  The  effect  of  a  preservative at different concentrations was also tested and  it  was  easy  to  see  which  preservative  levels  that  caused  an  inhibition of the microbial activity.

• Riva,  M.,  D.  Fessas,  and  A.  Schiraldi,  Isothermal  calorimetry  approach  to  evaluate  shelf  life  of  foods. Thermochim. Acta, 370 (2001) 73-81.

Calorimetric  measurements  were  made  on  three  food  systems  (eggs,  milk  and  a  salad)  at  different  (constant)  temperatures.  The  time  of  an  increase  in  the  measured  thermal  power  –  indicating  the  onset  of  degradation  processes  –  correlated  well  with  other  measures  used  to determine shelf-life.

• Alklint,  C.,  L.  Wadsö,  and  I.  Sjöholm,  Effects  of  modified  atmosphere on shelf-life of carrot juice. Food Control, 15 (2004) 131-137.

Alklint, C., L. Wadsö, and I. Sjöholm, Accelerated storage  and  isothermal  microcalorimetry  as  methods  of  predicting  carrot  juice  shelf-life.  J.  Sci.  Food  Agric.,  85 (2005) 281-285.

In  these  two  papers  the  microbiological  spoilage  of  carrot  juice  is  investigated.  Carrot  juice  is  an  interesting  spoilage  model  as  it  has  a  short  shelf  life  because  of  its  non-acidic  nature and its high content of soil microorganisms.

Seed germination

• Calvet, E. and H. Prat, Recent progress in  microcalorimetry (1963) Oxford: Pergamon Press.

In the third part of the English translation of this interesting  book  Prat  describes  several  measurements  on  germinating  seeds,  for  example  the  influence  of  temperature  of  the  germination  of  wheat  grain  (several  references  to  Prat’s  original work are given).

• Dymek,  K.,  et  al.,  Effekt  of  pulsed  electric  field  on  the  germination of barley seeds. LWT - Food Sci. Technol., 47 (2012) 161-166.

Exposure  of  germinating  barley  to  a  pulsed  electric  field  treatment  affects  radicle  emergence  without  significantly  affecting  the  seeds’  metabolic  activity,  as  quantified  by  isothermal calorimetry.