Food Biotechnology - Science topic

Molecular fluorescence spectroscopy is one of the most sensitive and highly selective spectroscopic methods, which can detect extremely low amounts of chemical substances. In the milk industry, it is used for the determination of vitamins, fatty acids, residual amounts of antibiotics, and the identification of different milk species in dairy products.

Also check https://www.mdpi.com/1420-3049/24/7/1244/pdf-vor

This method is recommended by the International Commission for Bee Botany:

Ten grams of honey is dissolved in 20 ml of warm water (40 C).

The solution is centrifuged for 10 min at 2500 r/min, the supernatant solution is decanted, and the sediments are collected into a conical tube and treated with an acetolysis mixture (acetic anhydride : conc. sulphuric acid = 9:1 V/V) for approximately 30 min at room temperature.

After treatment with the acetolysis mixture, the sediments are rinsed with distilled water, centrifuge for 5 min at 2500 r/min, and preserve for study.

Also, you can compare the performance of each biochemical compound related to any factor analyzed by DCA or NMDS using the mentioned software in comparison with that of outcome from control samples (plant cultured alone without bacteria).

Best,

Saeed

Dear Kumari, your question is from four years ago. Do you still need an answer?.

Hi,

Some properties were similarity between species . But note, Aspergillus oryzae are not Aflatoxin producing

Sorbitol fermentation by Acetobacter spp is a well known process. If you can lay your hnds at some of those old references you will get references of sorbitol estimation without HPLC, because in those early 1970s HPLC was not so common (at least in India).

Is a simple, general "rule" or calculating method.

1. You give the sample weight in [g] (In your case 1 g)

2. You give the final volume (after digestion) in [ml] (In this case 100 ml)

Note: the volume of acid for digestion isn't important, and the volume used for analysis (50ml) also not important (if there was not a further dilution from 100 ml).

3. The calculating factor = volume / weight = 100 / 1 = 100 [ml/g]

4. Your final result in [mg/kg = ppm] in original (solid or not) food sample will be (for example the measured ICP-OES result was = 4.5 mg/l potassium)

= 4.5 mg/l * 100 ml/g = 450 mg/kg !!!!

and mg/l * l/kg = mg/kg !!!!

Explanation: if you give the sample weight in kg and final volume in liter

(in this case 0.001 kg and 0.1 liter) the calculating factor will be

0.1 liter / 0.001 kg = 100 liter/kg (= the same number = 100 ml/g)

and your final result = 4.5 mg/l * 100 l/kg = 450 mg/kg.

To calculate the result for 100 g original food sample - divide that by 10.

(potassium content =) 45 mg per 100 g food.

I think, this article will be helpful for you.

Dear Shreenidhi,

I am also intersted ... I would appreciate if you could give more details about your project. 

Email: mohamad.hamoud-agha@unilasalle.fr 

Thanks 

The traditional way would be centrifugation. Other methods would be for filter membranes but would require specific equipment. Sedimentation does not always occur, it depends on the strain. Evaporation and drying may be an option but temperature control is required.

Hello Dear,

You can see the following Links. I hope it helps you.

Most likely a pigment made by an obligate aerobic organism like Pseudomonas. I have investigated a similar problem observed in Mozzarella cheese (usually soaked in Salt saturated water before packing in a plastic film). The film used usually has low oxygen penetration coefficient and the cheese lasts for the expected length of shelf-storage time. However, in that specific case the film supplier ran out of the regular film so he substituted it with a film material that was more permeable to Oxygen. Guess what! Oxygen interned the package and allowed the obligate aerobic organism to grow and produce the red pigment. 

We were able to isolate the organism and show it will not grow or produce the pigment in absence of air (20% Oxygen).  But upon exposure to oxygen the pigment was produced. It is a Phenazine Pigment.

Thank you, Miss Assel and Miss Zahira!

It is argued that milk heat treatment, pasteurisation and sterilisation in particular, has an adverse effects on lactose and protein quality.

I have the same opinion with Ogori AKAMA.

Dear Dr Hatab

This is an interesting project  and I would be very interested in collaboration with you too, if you can give me a summary of your research the possibility of funding can be  discussed. I am currently involved in nutraceuticals / functional foods in the prevention of cardiovascular diseases, diabetes, metabolic syndrome etc.

Best wishes and good luck with this interesting project

Khalid

I agree with Rafik Karaman answers ...good luck.

hi, if you want to analize gluten in foods there are to ways to do it:

1. if you want to know if it is present  or not (qualitative method) you can use rapid kits for gluten detections suh as rapid 3D from Neogen(USA) or Gluten Check Flow Through from BioCheck (UK). Easy to use and easy to read, without equipment

2. if you know how much are (quantitative method) you can use ELISA kits like Veratox from Neogen (USA) or Gluten Check from BIoCheck (UK). You need a centrifuge. a water bath and an ELISA reader.

I hope it helps you.

The content of casein in milk is determined by two measurements of infrared absorbance in a milk sample by infrared spectrometry before and after a separation of the casein. The casein content is calculated by use of absorbance data recorded during the two absorbance measurements. The new method is considerable faster than the known wet-chemical methods, such as the normal wet chemical reference method for casein determination in milk using a Kjeldahl nitrogen determination of the milk sample, then a coagulation of the milk, and finally a Kjeldahl nitrogen determination of the filtrate. Further the new method provides a more reliable accuracy than the know determination using a single infrared analysis of a milk sample.

Yeah this is under my consideration. I will talk this with my tutors tomorrow. Thank you for your reply. 

Hi there!

Usually lipid oxidation values are displayed as mg MDA/kg sample or mg TBARs /kg sample, could be mg or other units accordingly to method used. To transform the values from the TEP standard curve to these units, there is a factor, called K factor. It uses data from you standard curve, concentration, recovery and goes on. I recommend read the following article:

Evaluation of the 2-thiobarbituric acid method for the measurement of lipid oxidation in mechanically deboned gamma irradiated chicken meat (Food Chemistry, v. 80, p. 433-7, 2003)

Heliana de Azevedo Gomes, Edir Nepomuceno da Silva, Marcos Roberto Lopes do Nascimento a, Henrique Takuji Fukuma 

Thank you for your attention and explanations. 

Dear Prof. Karbassi,

Thank you so much for your comments. I have measured Hg and other metals especially Cd,As,Se. Pb etc. and their concentrations were not really high in the biomass when I compared it with maximum permissible limits in drinking water and or plants as set by WHO guidelines. This looks good since my further aim is to assess the potential of biomass as feed. 

Thanks for your feedback.

Geetanjali

Washing is a common step after fermentation in purpose to enhance the color, processing and others. however, it also could be use as the step to stop the fermentation process since it remove the pulp from the cocoa beans. Based on our experience in the field, washing is an effective method to stop the fermentation process so that it will not continued during drying process. If it is not washed, the fermentation process will continued during drying process resulted in the continuous chemical changes in cocoa bean. And yes, it will affect the composition of dried cocoa beans.  Depend on drying condition and the duration, it could give you positive result (advantage) or negative result (disadvantage).

My suggestions, first you have to analyse the survival ability of your bacteria in artificial rumen fluids and analyse the bacterial growth at different time intervals. Here you can get clear idea and then you can go for gas production analysis.

Contact Gerhard Knol. As Food Technologist he has experience with meat, special poultry, during working for Meyn FPT Company and later also gas- experience for packaging of meat during working for the Messer group.

His mail address is: gerhard.knol@gmail.com 

Yes, I understand. You ask why? I answered why and further provided a solution if using glucose oxidase to avoid the problem.

Basically, the by product of glucose oxidase is hydrogen peroxide which can contribute to the degradation of the egg protein molecules. Hydrogen Peroxide H₂O₂ has oxidising and reducing properties depending on the conditions... This can aid in protein degradation. It is recommended to use a catalase or peroxidase to break down H₂O₂ into water.

Hope this makes sense =)

PS. Catalase was not mentioned in question.

Dear Fellow researcher,

Just wondering, did anybody face 'bubble problem' when you pour your reaction mixture into the cuvettes for spectrophotometric reading in TBARS method?. I tried couple of methods and at the end I got too much small air bubbles in the cuvette  which gave me unstable absorbance all the time.

Please share your experience.

Thanks in advance,

Firstly peel off the roots. Then cut the roots into very thin slices and dip in 1 % SMS/KMS  solution and dry under 50 to 55 degrees centigrade by spreding on tray/cabinet dryer until reduce the moisture content < 3%. Then gring them in to flour, seive by a seiver for required particle sizes and store them in an airtight container.

Dear dr. 

The attached article will  help.

Excellent answers all round. And in addition, we may consider hurdles those forms of Unit Operations with a focus on preservation, i.e. shelf-life and food safety promotion. From food technology, we see the order of unit operations adopted for any food production processes, depends on a range of factors - but mainly the type of product desired. So, I agree with Jagan above, the combination of hurdles adopted will depend on the food product. Another interesting concept is to consider parallel versus sequential/ consecutive hurdles. Examples of parallel hurdles? Storing acidified food @ low temperature produces parallel hurdles of low pH and low temperature. Products with modified atmosphere packaging are frequently stored at low temperature.

kindly refer  to the attached files 

 regards 

there are geraniol commercially.

I have done the preparative TLC, but I need in milligram level for the application. From TLC I got only microgram scale of oligos. Anyways thank you Jai and Sandesh

I support the previous points that barley properties will vary, also given variation in the malting processes. However this article outlines the overall physical changes, hope it helps!

Dear dr. Ceruti

The attached article will be helpful for you.

with regards

 As I understand you are intending to develop cellulose nanocrystal and essential based film. Well, you do need a matrix either a polymer or biopolymer like gelatin, pectin or anything. For a trial you can use solvent casting, later on you can plan for extrusion. You can consult some of our papers where we use essential oil and nanopartilces.

The additives proposed by Giuseppe are good for the bread dough because the dough processing is long (from 3 till 12 hours) and moisture content is high (about 42-45%). For the noodles success of the Ascorbate and/or Cysteine salts addition is questionable because both the time of processing (less than 1 hour) and moisture content (30-32%) are too small.

I'm not sure what's your point. You may want to look into different flavour extraction methods. Doing the study of volatile aromatic compounds would be interesting in this case. You have to be very careful in selecting different extraction methods like SPME, Purge and Trap, SDE. It is always better to combine different extraction methods to find the best result. I would suggest you to use two dimentional GC, in coupling with TOF (GC × GC/TOF-MS). This is very sensitive and recently used technique. 

 Ground sample (1 gm) was homogenized at a speed of 13,500 rpm for 2 min in 11 ml of chloroform/methanol (2:1, v/v).

After this processes, have to be three layer. In the top layer comprises ground sample, central layer comprises methanol, and bottom layer comprises Chloroform and oil. You must take 7 ml into the bottom layer. Then you must continue other process. The oil is soluble in the chloroform but not soluble in the methanol. So, you can obtained correct (higher) value.

Probiotic (lactic acid) bacteria are anaerob. Juices must be deaerated before inoculation. Make sure after inoculation, 

Dear Diptiman Choudhury basend on my knowledge about gut colonization by Lactobacillus I think that the result of your research could be reached:

1 - using (or isolating) a Lactobacillus strain endowed with high adhesion properties to human gut ;

2 - growing it under condition promoting adhesion

3 - carrying out in vitro experiment to verify if it can adhere after different killing treatment (please note that many molecules involved in adhesion are sensitive to physico-chemical treatments)

4 - verify in in vivo experiments (eg. mouse) the best result from step 3 so, in addition, to understand how long it can colonise (or persist in) the gut

The immunostimolation by dead lactobacillus cells should have been already published (sorry I do not remember the paper!) so you can take advantages from that results.

However, in order to reach you goal I have some problem to understand your previous questions.

Wishing you successfull experiments

Best regards

FBaruzzi

You could try to evaporate the solvent (70% ethanol) until you obtain dry onion extract. Then you can prepare the desired concentrations by dissolving the known amount of dry extract in absolute ethanol.

Hello,

As Mr. Mushafau Adebayo Oke stated previously, there are not only one paper related with the subject. Lactic acid bacteria are used for food preservation for thousands of years and in bread production showed very good results. Breads prepared with sourdough are now again in food trends and are used to reduce the use of preservatives and food additives and to improve the taste, smell and aroma of breads.

Some papers you will find on this site if you are searching for ”sourdough and mould”.

Some papers you will find attached.

Dear Han,

If you want to identify and accurately quantify the alfa-tocopherol in brown rice , you can not simply extract with organic solvent and analyse using UV-VS. There are may steps to follow:

1. take around 4 g of sample into glass sample tube add 30 mL of Ethanol and 10 mL of 50 % KOH solution saponify at 100 degree for 30 minutes.

2. Cool it down asap, transfer saponified solution into 250 mL of separatory flask add 50 mL of D.I water and 50 mL of Hexane gently shake it for 2 minutes. Let it separate.

3. Collect the top Hexane layer into clean flask, repeat the extraction with second portion of 50 mL of Hexane.

4. Collect Hexane extract wash with 50 mL of D.I water and neutralize you extract.

5. Accurately transfer 10 mL of Hexane into 15 mL of test tube and purge it under nitrogen until dryness, than dissolve it with 2 mL of methanol vortex it for 2 min. Your sample is ready to analyse with HPLC UV, with C 18 250x4.6 mm, 5 um column, at 294 nm. This a standard procedure to analyse Fat Soluble vitamins, Vitamin A, Vitamin E (alfa tocopherol ), Vitamin D and Vitamin A precursor Beta carotene in food matrix

Please not that using UV-VS you are only able to check pure alfa tocopherol standard solution concentration, but you can't check sample extract, because your sample extract may have Viamin A, D, beta caroten and other isomers of tocopherol (tocopherol has 8 common isomers ). 

So, you have saponify your sample first remove any lipid interferences, than extract, concentrate, separate on C18 than quantify.

A very common method for following protein degradation in some food products is quantifying total nitrogen, peptide nitrogen and amino acid nitrogen separately (or even just total nitrogen and non-protein nitrogen): it will give you an idea of how intact are the proteins and how intense is the degradation. The quantification of nitrogen is through Kjeldahl.

sugar is about 3-5 percent

You can please follow the link below to obtain valuable informations:-

You can also download pdfs of the files attached herewith.

If this beverage is acid, say the pH of which is around 4.5 or below, you can use polysaccharide whose surface carry negative charge like pectin/ Soy Protein Polysaccharide and so on 

dear Patrick, thanks a lot for you important hint, yours Peter

Before doing the PCR, you could separate prokaryotic from eukaryotic DNA  by the presence of methylated CpG motifs (usually not methylated in prokaryotic DNA, whereas the majority of them are methylated in eukaryotic DNA). Some column kits able to bind methylated CpG motifs does exist.

if you want to analyse free phenols in fruit beverage, you can go for ANS titration method....

Dear colleague,

I think is important to investigate this interaction because I also found a kind of interaction between the fiber and calcium carbonate in a enteral solution.

Hello greetings.

I leave these books hope will be your profit. I personally think they are very good and could get you out of doubt.

The presence of their lipid anchors and/or the Tween 80 might be expected to make your samples behave this way. Did you do the multiday dialysis against water these preps usually require? Tween 80 has a cmc in water of 12uM and is thus very hard to remove by dialysis.

It will depend on the size of your bacteriocin.  My guess is that most bacteriocins will NOT be concentrated in this manner as most of the ones from lactic acid bacteria (that have relevance as food pathogen inhibitors) are small molecules, around 2,000-3,500 mol. wgt, so unless they complex with some other molecules, you won't be concentrating them.  But that is OK, because you will be 'cleaning up' the sample from most of the larger molecules that will be retained, but I would suspect the bacteriocins would elute through the filter and be in the filtrate.  You can easily determine the amount retained/lost by doing activity titer before, and after Centricon ultrafiltration.  If you have a vacuum dryer, one easy way would be to use Sep-Pak C18 cartridges hooked up to a syringe.....pass the bacteriocin-containing culture broth through that....everything will bind to the C18 matrix (eluate should look clear; cartridge will appear 'brown' by retained media proteins), and then using step-wise 10-ml rinses pushed through the cartridge by way of a syringe....wash with Isopropanol:  0% (water), 10%, 20%, 30%, 40%, 50%, 60%, 100%......dry these down with a vacuum concentrator if available and resuspend with water/buffer of your choosing.  You will likely find that much of the 'brown' protein content elutes somewhere in the 10-20% fractions and hydrophobic bacteriocin molecules in the 30-50% fractions. A simple way to use hydrophobic nature of these molecules to your advantage in quasi-purification.  Similarly, another way would be ammonium sulfate fractionation....stirring different media samples with different levels of ammonium sulfate saturation to selectively precipitate bacteriocins (0% ammonium sulfate, 20%, 40%, 60%), centrifuge, decant, resuspend pellet with water/buffer and check to see which percent cutoff may selectively precipitate your bacteriocin peptide. If you produce your bacteriocin in MRS broth, ammonium sulfate will cause the Tween 80 to flocculate at the surface upon centrifugation and you may want to collect that as I often found that is where the bacteriocin is found....in that surface flocculated film that can actually be scooped off the top (and resuspend that in water).  Good luck....these procedures can be found in the literature.

Also, in freeze dried sourdough production the LAB survival rate is increased if the culture is cold-adapted for 2h at a temperature with 15 oC lower then the cultivation temperature before freezing.

I am not sure what you mean by 'synthetic phages'?  Do you mean, bacteriophages that are harvested manually from bacteria or recombinant DNA-based bacteriophages?  Presuming the former, the use of bacteriophages as a food preservative faces a difficult challenge in that the lytic bacteriophages that are generated on a particular host are subject to restriction modification by that host whereby the phage DNA is modified and not considered 'foreign' and not degraded. That is the main problem....the recovered bacteriophage work best on that one host strain, likely showing a very high efficiency of plaquing (EOP). The problem is, as a food preservative, the antimicrobial ( i.e., bacteriophage) should work equally well on all targeted strains, such as E. coli O157:H7 for instance.  If it is propagated on 1 strain of E. coli O157:H7, it should work on all E. coli O157:H7 strains and not just work well on the 1 strain it was propagated on. Otherwise it renders the preservative with little or no effect in practical commercial application.  Aside from that problem, is the problem with 'inhibition kinetics'....bacteriophage are relatively large particles (compared to acid chemical antimicrobial molecules like lactic acid), they are finite in number and therefore as they interact with the food matrix, they are 'tittered out of solution' so to speak and the amount remaining is that much less, and also they require a direct contact and injection of their DNA into the targeted host bacteria, so it would likely only have application on the surface of a food, not after it is mixed into a food (like ground beef) where the food matrix may bind and complex with bacteriophage particles, or coat/cover/conceal targeted bacteria. So even on the surface of a food, what kind of titer is required in solution to provide coverage of the surface with bacteriophage no further apart from each other than the length of a bacterial cell?....since once they land on a surface, they are not planktonic anymore and are somewhat fixed in position. Good luck.

Patrick thank you very much for the information the second link is very close to what I am looking for and will play around with the software and will let you know the progress.

If you could see following symptoms, definitely it can be due to N-deficiency in culture medium.  

The plant becomes light green in color. The older leaves are

noticeably chlorotic and begin to turn yellowish-orange and die from the tip.

Change the culture solution regularly (at least twice a week) and add

nitrogen to give a concentration of 80 ppm in the culture solution.

Regards!

Darshani

May be it will depend on the cryoprotectant, but we have not found any negative effect using skimmed milk. The survival during the freeze drying step improves significantly without decline the adhesion of the probiotics in the intestine.

In December 2013 the European Food Safety Authority EFSA (the European FDA) published its first full risk assessment of aspartame. "The opinion concludes that aspartame and its breakdown products are safe for general population (including infants, children and pregnant women).

The current Acceptable Daily Intake (ADI) of 40mg/kg bw/day is considered protective for the general population and consumer exposure to aspartame is well below this ADI. However, in patients suffering from the medical condition phenylketonuria (PKU), the ADI is not applicable, as they require strict adherence to a diet low in phenylalanine (an amino acid making up proteins found in many foods)."

More info here: 

You can use a similar method to them

In addition to the above answers, temperature and soil moisture may be included.

The cereal-cyst nematode was first recognized as a parasite of cereals in

Germany in 1873 by J.Kuhn and is now recorded in most wheat-growing regions of the world. Cyst nematodes were recognized for many years as the cause of yield loss in cereal crops in most European countries and now in almost wheat-growing regions of the world. It was known in most of these countries as the oat-cyst nematode because the greatest effects of disease were observed in oats. In recent years, however, most attention in Europe has been directed toward control of the disease in barley.

Cereal cyst nematodes attack only members of the grass family (Poaceae). They enter only the meristematic tissue near root tips and the feeding process causes different symptoms to occur on different cereal crops. Wheat roots become bushy, knotted, and shallow roots become thickened and shortened, and barley roots exhibit no readily discernable symptoms. Leaf tips often become discolored: reddish-yellow on wheat, red on oats, and yellow on barley. Plants of each cereal crop may become stunted in patches Root damage by H. avenae often also favors greater colonization of roots by root-rotting fungal pathogens and by saprophytic bacteria, fungi, and non-plant-parasitic nematodes. These secondary organisms cause more intense rotting and discoloration than that caused by the plant-parasitic nematode itself.

Some researchers tested the efficiency of about six extraction methods for the recovery of females and cysts of the cereal cyst-nematode, Heterodera avenae, from a range of soils. Methods that included elutriation were best.

A diet high in vegetables is not likely to induce gout in an otherwise healthy individual.  Gout is traditionally associated with diets low in vegetables and high in meats etc.  As such there is most likely not a large demand for reduced purine cultivars.  The moderation/elimination of non vegetable matter in the diet will usually lead to a remission of symptoms.  

In regard to the physiology of the plant cultivars themselves a reduction in purine levels could have a drastic impact on growth.  Endogenous cytokinins are N- alkylated/arylated PURINES.  If the reduction of purines reduced the active level of Cytokinins the plant would be likely to suffer

Hello Szymon,

Rep-PCR using the (GTG)5 primer has been proven to give very good results. It has been tested in Lactobacilli and Enterococcus and creates fingerprints which allow differentiation to the species level. Have a look at the attached files but there's a lot more of them using (GTG)5. You may have to do some optimization with regards to magnesium concentration and annealing temperature in your PCR in order to get satisfying resolution and clarity, but I believe that the result is very satisfying.

All the best

Panos

Hello Lavinia,

   I will give you the possible/plausible reasons for all your queries. 

1) First of all it is not possible to spray dry when you have higher TSS. The optimum TSS for any juice around 20-30% only (refer research paper). But at high TSS if you can dry the sample,then we have a solution to get finer power. Try the  following settings independently or in combination: increase the atomization pressure kg/cm2(nozzle),decrease the feed rate(ml/min), increase the aspirator air flow rate m3/hr so more will the pressure automatically your product will stay in the top of the chamber for shorter period of time. 

2) if you try my first suggestion, you wont get sticky issues. otherwise you play with the lower temperature then the one you have tried.

3)By doing preliminary exp, you have to choose the best filler or fillers in combination and their quantity, to completely retain the flavor of your material.

Hope it will work for you . BEST OF LUCK

The reason why most papers use this technique is because it is the most simple approach. Believe me , once you get used to it you'll try to adapt all your problems to this technique

Dear Sruthi,

You have to be more specific...there are too many analytical instruments that are used in the food industries. Please state the type of product and the parameters (compounds or quality) measurements that you want to analyse. 

Dear Sir,

Agree with Carlos, you should prepare your own ascorbic acid standard curve. It is not difficult to do anyway. Using other's vit.C standard curve may give you inaccurate data because the type of instrument or mechanism of detection may not be the same as what you are using for your sample measurement. The skill of the operator also may affect the accuracy of the data/curve. Besides, you will get more satisfaction and more confident using your own standard curve, more so if you get the curve linearity of 0.99.

All the best.