This is an article from Dr. Stanley Bass, it's seems pretty useful.
INTRODUCTION
..... In my opinion and experience as a nutritional consultant in Natural Hygiene (I began studying nutrition in 1936), sequential eating represents the most advanced approach to understanding proper food combining.
After testing and retesting the concept on myself thousands of times, as well as on others, including the experience of Dr. Cursio, his family, his patients, as well as other Hygienic doctors - Dr. John Mega, Dr. Marvin Telmar, Dr. Anthony Penepent, etc.
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FOOD COMBINING
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Any quick digesting foods must wait till the slowest digesting foods leave the stomach before they can leave - a process which can take up to 6 or 8 hours. While waiting, the fruit, cooked and raw vegetables, and some of the starches undergo some decomposition and fermentation, producing gas, acid and even alcohol along with indigestion. .....
A RADICAL NEW CONCEPT OF DIGESTION
..... If there are 5 different types of food in the stomach at one meal, each eaten separately and in sequence, there will be 5 different kinds of digestion going on at the same time, each layer having different enzymes digesting each food, according to the needs of the food contained in that layer.
But when say 5 different foods are eaten at a meal, where each mouthful or bite is taken of a different food, then the entire stomach is filled with the same mixture. .....
ADVANTAGES OF REARRANGING THE SEQUENCE
One of my patients in my early days of practice absolutely refused to give up any of his accustomed, conventional, low-quality foods. In this case, feeling my hands completely tied, in desperation, I gave him all that he desired. The only change I made was to rearrange the sequence of his foods. Amazingly, all of his digestive problems vanished in just 3 days.
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SEQUENTIAL EATING REFERENCES
...... Grutzner fed rats morsels of food of 3 different colors. First the black, then the white second, and third the red color. Shortly after, the animals were sacrificed, the stomach frozen and then cut in sections. The different colored food was found to be in layers......
...... There was a famous case, written about by Beaumont, during the American Civil War, where a soldier received a gunshot wound which caused a large visible opening to appear in his stomach. His digestion was studied for a period of time by several doctors present, and they observed that his food digested in different layers.
SIMPLE TEST FOR ANYONE
One simple test that I used on myself was to eat different foods, one variety at a time, in sequence [all at one meal], for several different meals. Then when nature called, I examined the feces and was able to see different colors in the same feces. Watermelon which was reddish in color, was first, then tossed salad which was very dark brown was next, and cheese was very light tan was last. All were joined together, exiting the body in the same order as they were eaten.
Anyone can try this test, but to be accurate, the different foods must be eaten one at a time, and follow each other in sequence.
STRATA DIGESTION - A FORGOTTEN CONCEPT
..... How such an important concept as the strata digestion of food was bypassed and almost completely unnoticed for over 50 years since Howell's book was published, is a great mystery to me. .....
STOMACH - ILLUSTRATION
For purposes of illustration, I am presenting a diagram of the stomach and how 6 different foods eaten in sequence at one meal would form 6 different layers, during the time spent in the stomach.
In this diagram of the stomach, in layer 1, the bottom and first layer is where the first food eaten goes (the papaya). Layer 2 is where the 2nd food eaten goes (the tossed salad). Layer 3 is where the corn on the cob goes, etc. In this meal we are using 6 different foods, giving us 6 layers. ......
With this meal, after 30 min. the papaya will leave the stomach, and layer 2 - the tossed salad, will move down to layer one's place.
Layer 2 will shortly thereafter leave the stomach too.
Then the corn in layer 3 moves down and 15 min. later, it will leave the stomach ....
..... As each layer leaves, the stomach size gets smaller and feels more comfortable. Each layer digests separately, without mixing and without disturbing its adjacent layers.
BASIC RULE - WATERY FOODS FIRST
To simplify this concept of sequential or layered eating, the basic rule or principle can be stated as follows:
Eat the most watery food first .....
BAD COMBINATIONS TO AVOID
The following represents some examples of bad combinations to avoid
Mixing dried sweet fruit, honey, maple syrup or bananas with nuts or seeds
Mixing starch foods with fresh or acid foods or fruits
Mixing dried sweet fruits with acid fruits.
Never eat dried sweet fruits with or after concentrated proteins
Eating raw, fresh or dried fruits after any cooked food
Avoid drinking beverages or even water during or after meals
CHEW ALL FOOD CLOSE TO LIQUID
For best digestion - chew all food close to a liquid before swallowing.
Also in the 14th edition of Howell's Textbook of Physiology on p.777 is some very interesting research:
Abbe Spallanzani (1729 - 1799), one of the older observers on gastric digestion, found that cherries and grapes, when swallowed whole, even if entirely ripe, were usually passed unbroken in the stools. ....
We can assimilate only those foods which are most liquified. .....
EAT WITH ATTENTION
An excellent practice is to eat with 100% attention on the taste of the food. See Self-mastery through Attentive Eating .....
DIGESTION TIME OF VARIOUS FOODS
(approx. time spent in stomach before emptying). ........
Water
when stomach is empty, leaves immediately and goes into intestines,
Juices
Fruit vegetables, vegetable broth - 15 to 20 minutes.
Semi-liquid
(blended salad, vegetables or fruits) - 20 to 30 min.
Fruits
Watermelon - 20 min.digestion time.
Other melons - Canteloupe, Cranshaw, Honeydew etc. - 30 min.
Oranges, grapefruit, grapes - 30 min.
Apples, pears, peaches, cherries etc. - digest in 40 min.
Vegetables
Raw tossed salad vegetables - tomato, lettuces, cucumber, celery, red or green pepper, other succulent vegetables - 30 to 40 min. digestion. -
Steamed or cooked vegetables
Leafy vegetables - escarole, spinach, kale, collards etc. - 40 min. - Zucchini, broccoli, cauliflower, string beans, yellow squash, corn on cob - all 45 min. digestion time
Root vegetables - carrots, beets, parsnips, turnips etc. - 50 min.
Semi-Concentrated Carbohydrates - Starches
Jerusalem artichokes & leafy, acorn & butternut squashes, corn, potatoes, sweet potatoes, yam, chestnuts - all 60 min. digestion.
Concentrated Carbohydrates - Grains
Brown rice, millet, buckwheat, cornmeal, oats (first 3 vegetables best) - 90 min.
Legumes & Beans - (Concentrated Carbohydrate & Protein)
Lentils, limas, chick peas, peas, pigeon peas, kidney beans, etc. - 90 min. digestion time
soy beans -120 min. digestion time
Seeds & Nuts
Seeds - Sunflower, pumpkin, pepita, sesame - Digestive time approx. 2 hours.
Nuts - Almonds, filberts, peanuts (raw), cashews, brazil, walnuts, pecans etc. - 2 1/2 to 3 hours to digest.
Dairy
Skim milk, cottage or low fat pot cheese or ricotta - approx. 90 min. digestion time
whole milk cottage cheese - 120 min. digestion
whole milk hard cheese - 4 to 5 hours digestion time
Animal proteins
Egg yolk - 30 min. digestion time
Whole egg - 45 min.
Fish - cod, scrod, flounder, sole seafood - 30 min. digestion time
Fish - salmon, salmon trout, herring, (more fatty fish) - 45 min. to 60 digestion time
Chicken - 1½ to 2 hours digestion time (without skin)
Turkey - 2 to 2 ¼ hours digestion time (without skin)
Beef, lamb - 3 to 4 hours digestion time
Pork - 4½ to 5 hours digestion time
(Editor's notes
Note1: raw animal proteins have much faster digestion times than the above times for cooked/heated animal proteins.
Note2: The digestion times given are under an ideal situation of eating only one food, chewing well, and having efficient digestion, as is the case e.g. after a fast. They are digestion times for optimally healthy persons, with good eating habits. The digestion times are to a large part derived from Dr. Gian-Cursio's and Dr. Bass' practices.
Digestion times are much longer on a conventional diet, and for persons with non-optimized digestive systems, or persons lacking in energy, and for meals with many ingredients put together haphazardly = not in the optimum sequential order.)
EAT SMALLER AMOUNT - FEWER VARIETIES
The smaller the amount of a particular food eaten, the less is the digestive time for that food. The greater the amount of a food eaten, the more is the digestive time prolonged.
..... Remember the less you mix and the fewer the varieties you use, the easier it is to digest and the less you will be tempted to overeat. The greater the variety, the greater the tendency to overeat.
THE IMPORTANCE OF BLENDED SALADS
Due to the liquification of vegetables by blending:
1 - Absorption and assimilation of its vitamins, minerals proteins etc. is increased to approximately 5 times as compare to eating and chewing the salad.
2 - A blended salad will digest and leave the stomach in 15 to 20 min. compared to 30 to 60 minutes for a tossed salad eaten whole......
Etc.
Conservation at energy in the digestive process is the key to all healing. (Success in healing is measured in terms of energy available. This was known by the early masters of Natural Hygiene) .....
BASIC PURPOSE IS SAVING ENERGY
..... Energy is the most important factor needed for recovery of health and it must be conserved at all costs and not wasted in unnecessary digestion. Sequential eating will maximize the conservation of energy without fail.